Units and Symbols Found in the UDUNITS2 Database
The UDUNITS2 package provides recognition and conversion of wide variety of measurement units. This page contains a full list of all of the units and prefixes, by name and by symbol, contained in the UDUNIT2 units database. Each entry shows the definition of the unit or symbol and lists the other units and symbols that share that same definition.
These tables are based on UDUNITS version 2.2.19
Units by Name
Unit  Plural  Formula  Definition  Symbol(s)  Other names 

abampere  abamperes  10 A  basic unit of electricity in the electromagnetic CGS system of units  
abfarad  abfarads  1e9 F  unit of electricity/magnetism (exact)  
abhenry  abhenries  1e9 H  unit of electricity/magnetism (exact)  
abmho  abmhos  1e9 S  unit of electricity/magnetism (exact)  
abohm  abohms  1e9 ohm  unit of electricity/magnetism (exact)  
abvolt  abvolts  1e8 V  unit of electricity/magnetism (exact)  
acre  acres  160 rod ^2  unit of area in the US Customary System, used in land and sea floor measurement, equal to 43560 square feet (exact)  
acre_foot  acre_feet  1.233489e3 m ^3  unit of volume used to describe largescale water resources in the United State; equal to the volume of one acre of surface area with one foot of depth depth (An “acre.foot”, however, is 1233.4867714897 m^3. Odd.)  
amp  amps  A  unit of electric current, synonym for ampere (Synonym for SI unit)  
ampere  amperes  Base SI unit  The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular crosssection, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2e7 newton per meter of length.  A  
amu  1.6605402e27 kg  standard unit for indicating mass on an atomic or molecular scale; is approximately the mass of one nucleon (either a single proton or neutron), and equivalent to 1 g/mol (Unit’s value is obtained experimentally)  u  atomic_mass_unit , atomicmassunit , unified_atomic_mass_unit  
angstrom  angstroms  1e10 m  unit of length equal to one hundredmillionth of a centimeter (1 meter/10**10) (Unit is temporarily accepted for use with the SI.)  Å , Å  ångström 
angular_degree  angular_degrees  (pi /180) rad  measurement of a plane angle representing 1/360 of a full rotation  °  arc_degree , arcdeg , degree 
angular_minute  angular_minutes  ° /60  measurement of a plane angle equal to 1/60 arc degree  ′ , ‘  arc_minute , arcmin , arcminute 
angular_second  angular_seconds  ‘ /60  measurement of a plane angle equal to 1/60 arc minute  “ , ″  arc_second , arcsec , arcsecond 
apdram  apdrams  60 grain  unit of mass in apothecaries’ weight system (is 1/8 apounce)  
apostilb  apostilbs  cd /(pi m ^2)  unit of illumination (exact)  blondel  
apothecary_ounce  apothecary_ounces  3.110348e2 kg  unit of mass; based on historical US troy weight system (is 1/12 troy pound)  troy_ounce  
apothecary_pound  apothecary_pounds  3.732417e1 kg  unit of mass; based on historical US troy weight system (is 5760 grain)  troy_pound  
apounce  apounces  480 grain  unit of mass in apothecaries’ weight system (is 1/16 appound)  
appound  appounds  5760 grain  unit of mass in apothecaries’ weight system (is same as a troy pound)  
arc_degree  arc_degrees  (pi /180) rad  measurement of a plane angle representing 1/360 of a full rotation  °  angular_degree , arcdeg , degree 
arc_minute  arc_minutes  ° /60  measurement of a plane angle equal to 1/60 arc degree  ′ , ‘  angular_minute , arcmin , arcminute 
arc_second  arc_seconds  ‘ /60  measurement of a plane angle equal to 1/60 arc minute  “ , ″  angular_second , arcsec , arcsecond 
arcdeg  arcdegs  (pi /180) rad  measurement of a plane angle representing 1/360 of a full rotation  °  angular_degree , arc_degree , degree 
arcmin  arcmins  ° /60  measurement of a plane angle equal to 1/60 arc degree  ′ , ‘  angular_minute , arc_minute , arcminute 
arcminute  arcminutes  ° /60  measurement of a plane angle equal to 1/60 arc degree  ′ , ‘  angular_minute , arc_minute , arcmin 
arcsec  arcsecs  ‘ /60  measurement of a plane angle equal to 1/60 arc minute  “ , ″  angular_second , arc_second , arcsecond 
arcsecond  arcseconds  ‘ /60  measurement of a plane angle equal to 1/60 arc minute  “ , ″  angular_second , arc_second , arcsec 
are  ares  dam ^2  unit of area equal to 100 square meters (Unit is temporarily accepted for use with the SI.)  a  
arpentlin  arpentlins  191.835 foot  unit of length in French regions; a linear arpent is of length 10 perch (10 rod)  
assay_ton  assay_tons  2.916667e2 kg  reference unit of mass for a body of ore; roughly equal to 29167 milligrams  
astronomical_unit  astronomical_units  1.495979e11 m  unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun (Unit’s value is obtained experimentally)  ua  
atmosphere  atmospheres  1.01325e5 Pa  unit of pressure, an international reference pressure intended to represent the mean atmospheric pressure at mean sea level at the latitude of Paris, France (exact)  atm  standard_atmosphere 
atomic_mass_unit  atomic_mass_units  1.6605402e27 kg  standard unit for indicating mass on an atomic or molecular scale; is approximately the mass of one nucleon (either a single proton or neutron), and equivalent to 1 g/mol (Unit’s value is obtained experimentally)  u  amu , atomicmassunit , unified_atomic_mass_unit 
atomicmassunit  atomicmassunits  1.6605402e27 kg  standard unit for indicating mass on an atomic or molecular scale; is approximately the mass of one nucleon (either a single proton or neutron), and equivalent to 1 g/mol (Unit’s value is obtained experimentally)  u  amu , atomic_mass_unit , unified_atomic_mass_unit 
avogadro_constant  6.02214179e23/mol  number of constituent particles (usually atoms or molecules) per mole of a given substance (Constant; value is +30e15)  
avoirdupois_ounce  avoirdupois_ounces  2.834952e2 kg  unit of mass equal to 1/16 avoirdupois pound, commonly used in the United States (16 oz = 1 pound = 7000 grains)  
avoirdupois_pound  avoirdupois_pounds  4.5359237e1 kg  unit of mass in avoirdupois system of weights (a system commonly used in United States)  lb  pound 
bag  bags  94 pound  unit of mass, for a traditional bag of portland cement  
bar  bars  1000 hPa  unit of pressure equal to 100000 Pascals, or about 0.987 atmospheres of pressure (Unit is temporarily accepted for use with the SI.)  
barie  baries  0.1 N /m ^2  unit of pressure equal to one dyne per square centimeter (exact)  barye  
barleycorn  barleycorns  inch /3  unit of length based in medieval laws of England and Wales, defining an inch as being 3 barleycorns long (length of a corn of barley); still the basis for current shoe sizes in Great Britain and Ireland  
barn  barns  100 fm ^2  unit of area, approximately the crosssectional area of a uranium nucleus (10e28 square meters) (Unit is temporarily accepted for use with the SI.)  b  
barrel  barrels  42 US_liquid_gallon  unit of volume used by US and Canadian petroleum organizations (The following is the definition of the petroleum industry)  bbl  
barye  baryes  0.1 N /m ^2  unit of pressure equal to one dyne per square centimeter (exact)  barie  
baud  bauds  Hz  unit of frequency, synonym for hertz (Synonym for SI unit)  Bd , bps  
becquerel (Is an alias because ‘1/s’ is already mapped to ‘hertz’ and ‘Hz’)  becquerels  1/s  unit of radioactivity; the activity of a quantity of material in which one nucleus decays per second (hence, equivalent to one unit per second) (SI derived unit with special names/symbols admitted for reasons of safeguarding human health)  Bq  
big_point  big_points  inch /72  unit of length equal to 1/72 inch, standardized unit in modern computerbased publishing for measuring font size and other small items on a printed page (contrast to printers_point)  
biot  biots  10 A  basic unit of electricity in the electromagnetic CGS system of units (same as abampere), named after JeanBaptiste Biot  
bit  bits  1  count  
blondel  blondels  cd /(pi m ^2)  unit of illumination (exact)  apostilb  
board_foot  board_feet  2.359737e3 m ^3  unit of volume equal to the cubic contents of a piece of lumber one foot square and one inch thick, used in measuring logs and lumber in the United States and Canada  
boiler_horsepower  boiler_horsepowers  9.80950e3 W  unit of power equal to the power required to evaporate 34.5 lb of fresh water at 212 degrees F in one hour; describes a boiler’s capacity to deliver steam to a steam engine  
Btu  Btus  1.05505585262e3 J  unit of energy, equal to the energy needed to cool or heat one pound of water by one degree F; this uses the International Steam Table (IT) calorie , defined by the Fifth International Conference on the properties of Steam (1956) (exact)  IT_Btu  
bushel  bushels  3.523907e2 m ^3  unit of volume defined as 2150.42 cubic inches or 4 pecks in the US Customary system (and formerly in England), where it is used as a dry measure  bu  
byte  bytes  8  octet  
C12_faraday  C12_faradays  9.648531e4 C  unit of electricity/magnetism  faraday  
calorie  calories  4.1868 J  unit of heat energy used in thermochemistry, the International Steam Table (IT) calorie defined by the Fifth International Conference on the properties of Steam (1956) (exact)  cal  IT_calorie 
Canadian_liquid_gallon  Canadian_liquid_gallons  4.546090e3 m ^3  unit of volume for liquids in the Imperial system (exact)  
candela  candelas  Base SI unit  The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540e12 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.  cd  
candle  candles  cd  unit of luminous intensity, synonym for candela (Synonym for SI unit)  
carat  carats  2e4 kg  unit of mass equal to 0.2 gram (defined 1907)  
celsius  celsiuses  degree_Celsius  unit of temperature, synonym for ‘K @ 273.15’ (degree_Celsius) (Synonym for SI unit)  ℃  degC , deg_C , degreeC , degree_C 
chain  chains  2.011684e1 m  unit of length equal to 66 feet (4 poles), or 1/10 furlong, a typical (historical) scale of land surveying  
chemical_faraday  chemical_faradays  9.64957e4 C  unit of electricity/magnetism  
circle  circles  2 pi rad  unit of angle in a plane signifying a full 360degree circle  cycle , revolution , rotation , turn  
circular_mil  circular_mils  5.067075e10 m ^2  unit of area equal to the area of a onemil diameter circle  
clo  clos  1.55e1 K .m ^2/W  unit of thermal resistance used in describing the insulating value of clothing; the amount of thermal resistance needed to maintain in comfort a resting subject in a normally ventilated room (air movement 10 cm/sec) at a temperature of 20 degrees C and a humidity less than 50%  
common_year  common_years  365 day  unit of time corresponding to a ‘normal’ calendar year, that is, one without insertion of a leap day  
conventional_mercury  conventional_mercuries  gravity 13595.10 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of mercury at 0 degrees C  Hg  mercury_0C , mercury_32F 
conventional_water  conventional_waters  gravity 1000 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of water (exact)  H2O , h2o  water 
coulomb  coulombs  s .A  standard unit of electric charge, the quantity of electricity transported in one second by a current of one ampere (SI derived unit)  C  
count  counts  1  bit  
cup  cups  US_liquid_gallon /16  unit of volume for liquid measure in the US Customary system, equal to 1/16 liquid gallon (exact)  US_liquid_cup , liquid_cup  
curie  curies  3.7e10 Bq  unit of radioactivity corresponding to 3.7 * 10e10 disintegrations per second (Unit is temporarily accepted for use with the SI.)  Ci  
cycle  cycles  2 pi rad  unit of angle in a plane signifying a full 360degree circle  circle , revolution , rotation , turn  
darcy  darcies  9.869233e13 m ^2  unit of area for measuring permeability to fluid, equal to 1 cubic centimeter of fluid with 1 centipoise viscosity in 1 second through a 1squarecentimeter cross section of porous medium 1 centimeter long at 1 atmosphere (porous solid permeability)  
day  days  24 h  period of time equal to 24 hours  d  
deg_C  degs_C  degree_Celsius  unit of temperature, synonym for ‘K @ 273.15’ (degree_Celsius) (Synonym for SI unit)  ℃  celsius , degC , degreeC , degree_C 
deg_F  degs_F  °R @ 459.67  unit of thermodynamic temperature  °F , ℉  degF , degreeF , degree_F , degree_fahrenheit , fahrenheit 
deg_K  degs_K  K  unit of temperature, synonym for kelvin (Synonym for SI unit)  °K  degK , degreeK , degree_K , degree_kelvin 
deg_R  degs_R  K /1.8  unit of thermodynamic temperature  °R  degR , degreeR , degree_R , degree_rankine 
degC  degsC  degree_Celsius  unit of temperature, synonym for ‘K @ 273.15’ (degree_Celsius) (Synonym for SI unit)  ℃  celsius , deg_C , degreeC , degree_C 
degF  degsF  °R @ 459.67  unit of thermodynamic temperature  °F , ℉  deg_F , degreeF , degree_F , degree_fahrenheit , fahrenheit 
degK  degsK  K  unit of temperature, synonym for kelvin (Synonym for SI unit)  °K  deg_K , degreeK , degree_K , degree_kelvin 
degR  degsR  K /1.8  unit of thermodynamic temperature  °R  deg_R , degreeR , degree_R , degree_rankine 
degree  degrees  (pi /180) rad  measurement of a plane angle representing 1/360 of a full rotation  °  angular_degree , arc_degree , arcdeg 
degree_C  degrees_C  degree_Celsius  unit of temperature, synonym for ‘K @ 273.15’ (degree_Celsius) (Synonym for SI unit)  ℃  celsius , degC , deg_C , degreeC 
degree_Celsius  degrees_Celsius  K @ 273.15  unit (and scale) of temperature, with same magnitude as the kelvin and a zeropoint offset of 273.15 (SI derived unit)  °C  
degree_E  degrees_E  arc_degree  unit of angle on a sphere  degreeE , degreeN , degreeT , degree_N , degree_T , degree_east , degree_north , degree_true  
degree_east  degrees_east  arc_degree  unit of angle on a sphere  degreeE , degreeN , degreeT , degree_E , degree_N , degree_T , degree_north , degree_true  
degree_F  degrees_F  °R @ 459.67  unit of thermodynamic temperature  °F , ℉  degF , deg_F , degreeF , degree_fahrenheit , fahrenheit 
degree_fahrenheit  degrees_fahrenheit  °R @ 459.67  unit of thermodynamic temperature  °F , ℉  degF , deg_F , degreeF , degree_F , fahrenheit 
degree_K  degrees_K  K  unit of temperature, synonym for kelvin (Synonym for SI unit)  °K  degK , deg_K , degreeK , degree_kelvin 
degree_kelvin  degrees_kelvin  K  unit of temperature, synonym for kelvin (Synonym for SI unit)  °K  degK , deg_K , degreeK , degree_K 
degree_N  degrees_N  arc_degree  unit of angle on a sphere  degreeE , degreeN , degreeT , degree_E , degree_T , degree_east , degree_north , degree_true  
degree_north  degrees_north  arc_degree  unit of angle on a sphere  degreeE , degreeN , degreeT , degree_E , degree_N , degree_T , degree_east , degree_true  
degree_R  degrees_R  K /1.8  unit of thermodynamic temperature  °R  degR , deg_R , degreeR , degree_rankine 
degree_rankine  degrees_rankine  K /1.8  unit of thermodynamic temperature  °R  degR , deg_R , degreeR , degree_R 
degree_T  degrees_T  arc_degree  unit of angle on a sphere  degreeE , degreeN , degreeT , degree_E , degree_N , degree_east , degree_north , degree_true  
degree_true  degrees_true  arc_degree  unit of angle on a sphere  degreeE , degreeN , degreeT , degree_E , degree_N , degree_T , degree_east , degree_north  
degree_W  degrees_W  1 degree_east  unit of angle on a sphere (units for negative direction)  degreeW , degree_west  
degree_west  degrees_west  1 degree_east  unit of angle on a sphere (units for negative direction)  degreeW , degree_W  
degreeC  degreesC  degree_Celsius  unit of temperature, synonym for ‘K @ 273.15’ (degree_Celsius) (Synonym for SI unit)  ℃  celsius , degC , deg_C , degree_C 
degreeE  degreesE  arc_degree  unit of angle on a sphere  degreeN , degreeT , degree_E , degree_N , degree_T , degree_east , degree_north , degree_true  
degreeF  degreesF  °R @ 459.67  unit of thermodynamic temperature  °F , ℉  degF , deg_F , degree_F , degree_fahrenheit , fahrenheit 
degreeK  degreesK  K  unit of temperature, synonym for kelvin (Synonym for SI unit)  °K  degK , deg_K , degree_K , degree_kelvin 
degreeN  degreesN  arc_degree  unit of angle on a sphere  degreeE , degreeT , degree_E , degree_N , degree_T , degree_east , degree_north , degree_true  
degreeR  degreesR  K /1.8  unit of thermodynamic temperature  °R  degR , deg_R , degree_R , degree_rankine 
degreeT  degreesT  arc_degree  unit of angle on a sphere  degreeE , degreeN , degree_E , degree_N , degree_T , degree_east , degree_north , degree_true  
degreeW  degreesW  1 degree_east  unit of angle on a sphere (units for negative direction)  degree_W , degree_west  
denier  deniers  1.111111e7 kg /m  unit of lineic mass density for fibers, equal to the mass in grams per 9000 meters (more common in United States and United Kingdom); a single strand of silk is approximately one denier  
dobson  dobsons  446.2 micromoles /meter ^2  DU  
dram  drams  avoirdupois_ounce /16  unit of mass in the avoirdupois system (the system commonly used in the United States) (exact)  dr  
dry_pint  dry_pints  US_dry_gallon /8  unit of volume for dry measure in the US Customary system, equal to 1/2 US dry quart (exact)  US_dry_pint  
dry_quart  dry_quarts  US_dry_gallon /4  unit of volume for dry measure in the US Customary system, equal to 1/32 US bushel (exact)  US_dry_quart  
dynamic  dynamics  gravity  (exact)  gp  geopotential 
dyne  dynes  1e5 N  unit of force, equal to the force that produces an acceleration of one centimeter per second per second on a mass of one gram (the standard centimetergramsecond unit of force) (exact)  
EC_therm  EC_therms  1.05506e8 J  unit of energy legally defined by the Council Directive of 20 December 1979, Council of the European Communities (now the European Union, EU);.roughly equal to 100,000 IT_Btu (exact (reference NIST Guide to SI Units))  
einstein  einsteins  mole  unit of chemical mass, synonym for mole (Synonym for SI unit)  
electric_horsepower  electric_horsepowers  7.460000e2 W  unit of power defined in the International System of Units as exactly 746 W; generally used for power used by electrical machines (exact)  
electron_volt  electron_volts  1.60217733e19 J  unit of energy equal to the work accelerating an electron through a potential difference of one volt (Unit’s value is obtained experimentally)  eV  electronvolt 
electronvolt  electronvolts  1.60217733e19 J  unit of energy equal to the work accelerating an electron through a potential difference of one volt (Unit’s value is obtained experimentally)  eV  electron_volt 
eon  eons  1e9 year  unit of time defined in astronomy as 1 billion years  
erg  ergs  1e7 J  unit of work, equal to the amount of work done by a force of one dyne exerted for a distance of one centimeter (in CGS base units, one gram centimetersquared per secondsquared) (exact)  
fahrenheit  fahrenheits  °R @ 459.67  unit of thermodynamic temperature  °F , ℉  degF , deg_F , degreeF , degree_F , degree_fahrenheit 
farad  farads  C /V  standard unit of capacitance; the amount which, when a capacitor is charged to a potential difference of one volt, carries a charge of one coulomb (SI derived unit)  F  
faraday  faradays  9.648531e4 C  unit of electricity/magnetism  C12_faraday  
fathom  fathoms  6 US_survey_feet  unit of length equal to 6 feet in the imperial and US customary systems, typically used for measuring depth of water  
fermi  fermis  1e15 m  unit of length equal to 10e15 meters, a typical lengthscale of nuclear physics  
firkin  firkins  barrel /4  unit of volume whose exact quantity depends on the type of barrel on which it is defined; in this table it is defined based on the oil barrel used by the petroleum industry (The following is exact regardless of the definition of “barrel”)  
fluid_dram  fluid_drams  US_fluid_ounce /8  unit of volume for liquid measure in the apothecary system, equal to 1/8 liquid ounce (exact)  fldr  
fluid_ounce  fluid_ounces  US_liquid_gallon /128  unit of volume for liquid measure in the US Customary system, equal to 1/128 liquid gallon (exact)  floz , oz  US_fluid_ounce , US_liquid_ounce , liquid_ounce 
foot  feet  12 international_inches  unit of length equal to 12 international inches, in the imperial and US customary systems; primarily used in the United States  ft  international_foot 
foot_H2O  feet_H2O  foot water  unit of pressure representing the pressure exerted by a column of water of 1 foot height at 4 degrees C  ftH2O , fth2o  footH2O , foot_water 
foot_water  feet_water  foot water  unit of pressure representing the pressure exerted by a column of water of 1 foot height at 4 degrees C  ftH2O , fth2o  footH2O , foot_H2O 
footcandle  footcandles  1.076391e1 lx  unit of illumination  
footH2O  feetH2O  foot water  unit of pressure representing the pressure exerted by a column of water of 1 foot height at 4 degrees C  ftH2O , fth2o  foot_H2O , foot_water 
footlambert  footlamberts  3.426259 cd /m ^2  unit of illumination (exact)  
force  forces  standard_free_fall  unit of force equivalent to the force generated by the effect of gravity  
force_gram  force_grams  gram force  unit of force, equal to the magnitude of the force exerted by one gram of mass in a 9.80665 m/s2 gravitational field (exact)  gf  gram_force 
force_kilogram  force_kilograms  9.806650 N  unit of force, equal to the magnitude of the force exerted by one kilogram of mass in a 9.80665 m/s2 gravitational field (exact)  kgf  kilogram_force 
force_ounce  force_ounces  2.780139e1 N  unit of force, equal to the magnitude of the force exerted by one ounce of mass in a 9.80665 m/s2 gravitational field (exact)  ozf  ounce_force 
force_pound  force_pounds  4.4482216152605 N  unit of force, equal to the magnitude of the force exerted by one pound of mass in a 9.80665 m/s2 gravitational field (exact)  lbf  pound_force 
force_ton  force_tons  2000 force_pound  unit of force, equal to the magnitude of the force exerted by one ton of mass in a 9.80665 m/s2 gravitational field (specifically a short ton of mass) (exact)  ton_force  
fortnight  fortnights  14 day  unit of time commonly defined as 14 days  
furlong  furlongs  660 US_survey_feet  unit of length equal to 1/8 mile or 10 chains  
gal  gals  cm /s ^2  unit of acceleration equal to 1 cm per second squared (Unit is temporarily accepted for use with the SI.)  
gallon  gallons  3.785412e3 m ^3  unit of volume for liquid measure in the US Customary system, defined as 3.785412 liters  US_liquid_gallon , liquid_gallon  
gamma  gammas  1e9 T  unit of electricity/magnetism (exact)  
gauss  gausses  1e4 T  unit of electricity/magnetism (exact)  
geopotential  geopotentials  gravity  (exact)  gp  dynamic 
gilbert  gilberts  7.957747e1 A  unit of electricity/magnetism  
gill  gills  US_liquid_gallon /32  unit of volume for liquid measure in the US Customary system, equal to 1/32 liquid gallon (exact)  US_liquid_gill , liquid_gill  
grade  grades  0.9 arc_degree  1/100 of a right angle (90 degrees)  
grain  grains  6.479891e5 kg  unit of mass equal to 1/7000 pound  gr  
gram  grams  1e3 kg  unit of mass equal to one thousandth of a kilogram (SI derived unit)  g  
gram_force  grams_force  gram force  unit of force, equal to the magnitude of the force exerted by one gram of mass in a 9.80665 m/s2 gravitational field (exact)  gf  force_gram 
gravity  gravities  standard_free_fall  unit of acceleration synonymous with standard rate of free fall (in earth’s gravity) (should be local)  
gray  grays  J /kg  unit of ionizing radiation, a measure of the absorbed dose of radiation; absorption of one joule of radiation energy by one kilogram of matter (SI derived unit with special names/symbols admitted for reasons of safeguarding human health)  Gy  
Gregorian_year  Gregorian_years  365.2425 day  unit of time based on the Gregorian Calendar, the one commonly used today; approximates the tropical year as 365 + 97/400 days  
hectare  hectares  100 are  unit of area equal to 100 are (‘hectoare’), or 10000 square meters (Unit is temporarily accepted for use with the SI.)  
henry  henries  Wb /A  unit of inductance; where a circuit’s current changes at a constant rate of 1 ampere per second, results in a generation of 1 V of potential difference (SI derived unit)  H  
hertz  hertzs  1/s  unit of frequency meaning one cycle per second (SI derived unit)  Hz  
horsepower  horsepowers  7.456999e2 W  unit of power originally corresponding to the estimated typical power of draft horses, calculated as lifting 33000 pounds one foot in one minute (550 footpounds/second) (shaft_horsepower is a unit of power as delivered by a drive shaft at its output (e.g., of a ship, aircraft engine, or helicopter rotor; typically not automobiles due to drive train losses))  hp  shaft_horsepower 
hour  hours  60 min  period of time equal to 60 minutes  h , hr  
inch  inches  2.54 cm  unit of length equal to 25.4 mm by definition, used in imperial and US customary systems  in  international_inch 
inch_H2O_39F  inches_H2O_39F  inch water_39F  unit of pressure representing the pressure exerted by a column of water of 1 inch height at 39 degrees F (exact)  
inch_H2O_60F  inches_H2O_60F  inch water_60F  unit of pressure representing the pressure exerted by a column of water of 1 inch height at 60 degrees F (exact)  
inch_Hg  inches_Hg  inch Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 inch height at 0 degrees C  inHg , in_Hg  
inch_Hg_32F  inches_Hg_32F  inch mercury_32F  unit of pressure representing the pressure exerted by a column of mercury of 1 inch height at 32 degrees F (exact)  
inch_Hg_60F  inches_Hg_60F  inch mercury_60F  unit of pressure representing the pressure exerted by a column of mercury of 1 inch height at 60 degrees F (exact)  
international_foot  international_feet  12 international_inches  unit of length equal to 12 international inches, in the imperial and US customary systems; primarily used in the United States  ft  foot 
international_inch  international_inches  2.54 cm  unit of length equal to 25.4 mm by definition, used in imperial and US customary systems  in  inch 
international_knot  international_knots  nautical_mile /hour  derived unit of speed at sea (Unit is temporarily accepted for use with the SI.)  knot , knot_international  
international_mile  international_miles  5280 international_feet  unit of length equal to 5280 feet, equal to 12 international inches, in the imperial and US customary systems; primarily used in the United States and other smaller countries with ties to the US or United Kingdom  mi  mile 
international_yard  international_yards  3 international_feet  unit of length equal to 3 international feet, in the imperial and US customary systems; primarily used in the United States  yd  yard 
IT_Btu  IT_Btus  1.05505585262e3 J  unit of energy, equal to the energy needed to cool or heat one pound of water by one degree F; this uses the International Steam Table (IT) calorie , defined by the Fifth International Conference on the properties of Steam (1956) (exact)  Btu  
IT_calorie  IT_calories  4.1868 J  unit of heat energy used in thermochemistry, the International Steam Table (IT) calorie defined by the Fifth International Conference on the properties of Steam (1956) (exact)  cal  calorie 
jiffy  jiffies  0.01 s  unit of time used in computer animation as a method of defining playback rate (multiple values have been proposed for the amount of time represented by a ‘jiffy’)  
joule  joules  N .m  standard unit of work or energy, equal to the work done by a force of one newton acting along a distance of one meter (SI derived unit)  J  
Julian_year  Julian_years  365.25 day  unit of time recognized by the International Astronomical Union for use in astronomy, defined as 365.25 days of 86400 seconds  
katal  katals  mol /s  unit of catalytic activity (property of a catalyst, such as an enzyme); expresses the ability to break 1 mole of bonds per second under specified conditions (SI derived unit)  kat  
kayser  kaysers  100/m  (exact)  
kelvin  kelvins  Base SI unit  The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.  K  
kilogram  kilograms  Base SI unit  The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.  kg  
kilogram_force  kilograms_force  9.806650 N  unit of force, equal to the magnitude of the force exerted by one kilogram of mass in a 9.80665 m/s2 gravitational field (exact)  kgf  force_kilogram 
kip  kips  1000 lbf  unit of force, equal to the magnitude of the force exerted by one thousand pounds of mass in a 9.80665 m/s2 gravitational field (exact)  
knot  knots  nautical_mile /hour  derived unit of speed at sea (Unit is temporarily accepted for use with the SI.)  international_knot , knot_international  
knot_international  knot_internationals  nautical_mile /hour  derived unit of speed at sea (Unit is temporarily accepted for use with the SI.)  international_knot , knot  
lambert  lamberts  (1e4/pi ) cd /m ^2  unit of illumination (exact)  
langley  langleys  4.184000e4 J /m ^2  unit of illumination (exact)  
leap_year  leap_years  366 day  unit of time corresponding to a calendar year with a leap day inserted  
light_year  light_years  9.46073e15 m  unit of length equal to the distance traversed by light in one mean solar year (365.2422 days), a typical lengthscale of astronomy  
liquid_cup  liquid_cups  US_liquid_gallon /16  unit of volume for liquid measure in the US Customary system, equal to 1/16 liquid gallon (exact)  US_liquid_cup , cup  
liquid_gallon  liquid_gallons  3.785412e3 m ^3  unit of volume for liquid measure in the US Customary system, defined as 3.785412 liters  US_liquid_gallon , gallon  
liquid_gill  liquid_gills  US_liquid_gallon /32  unit of volume for liquid measure in the US Customary system, equal to 1/32 liquid gallon (exact)  US_liquid_gill , gill  
liquid_ounce  liquid_ounces  US_liquid_gallon /128  unit of volume for liquid measure in the US Customary system, equal to 1/128 liquid gallon (exact)  floz , oz  US_fluid_ounce , US_liquid_ounce , fluid_ounce 
liquid_pint  liquid_pints  US_liquid_gallon /8  unit of volume for liquid measure in the US Customary system, equal to 1/8 liquid gallon (exact)  pt  US_liquid_pint , pint 
liquid_quart  liquid_quarts  US_liquid_gallon /4  unit of volume for liquid measure in the US Customary system, equal to 1/4 liquid gallon (exact)  US_liquid_quart , quart  
liter  liters  dm ^3  unit of capacity equal to 1000 cubic centimeters (The definition is exact. From 1901 to 1964, however, 1 liter was 1.000028 dm^3 (volume of 1 kg of water under standard conditions).)  L , l  litre 
litre  litres  dm ^3  unit of capacity equal to 1000 cubic centimeters (The definition is exact. From 1901 to 1964, however, 1 liter was 1.000028 dm^3 (volume of 1 kg of water under standard conditions).)  L , l  liter 
long_hundredweight  long_hundredweights  5.080235e1 kg  unit of mass; a British hundredweight, which is 8 stone * 14 pounds/stone  
long_ton  long_tons  2240 pound  unit of mass based on British imperial weight system  
lumen  lumens  cd .sr  unit of luminous flux, a measure of the total “amount” of visible light emitted by a source; one candelasteradian (SI derived unit)  lm  
lunar_month  lunar_months  29.530589 day  unit of time equal to the average time between successive new or full moons; equal to approximately 29 days, 12 hours, 44 minutes  
lux  luxes  lm /m ^2  unit of illuminance and luminous emittance, measuring luminous flux per unit area, and used as a measure of intensity of light; equal to one lumen per square meter (SI derived unit)  lx  
maxwell  maxwells  1e8 Wb  unit of electricity/magnetism (exact)  
mercury_0C  mercuries_0C  gravity 13595.10 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of mercury at 0 degrees C  Hg  conventional_mercury , mercury_32F 
mercury_32F  mercuries_32F  gravity 13595.10 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of mercury at 0 degrees C  Hg  conventional_mercury , mercury_0C 
mercury_60F  mercuries_60F  gravity 13556.8 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of mercury at 60 degrees F  
meter  meters  Base SI unit  The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.  m  metre 
metre  metres  Base SI unit  The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.  m  meter 
metric_horsepower  metric_horsepowers  7.35499e2 W  unit of power corresponding to a calculation of 75 kilogrammeters/second  
metric_ton  metric_tons  1000 kg  unit of weight equal to 1000 kilograms  t  tonne 
micron  microns  1e6 m  unit of length, a typical lengthscale of technology and science fields  
mil  mils  2.54e5 m  unit of length equal to 0.001 inch, a typical lengthscale for measuring wire diameters  
mile  miles  5280 international_feet  unit of length equal to 5280 feet, equal to 12 international inches, in the imperial and US customary systems; primarily used in the United States and other smaller countries with ties to the US or United Kingdom  mi  international_mile 
millimeter_Hg  millimeters_Hg  mm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 mm height at 0 degrees C; approximately (within 0.000015%, generally below measurement error) 1 Torr, which is 1/760 standard atmospheric pressure  mmHg , mm_Hg , mm_hg , mmhg  torr 
millimeter_Hg_0C  millimeters_Hg_0C  mm mercury_0C  unit of pressure representing the pressure exerted by a column of mercury of 1 mm height at 0 degrees C (exact)  
minute  minutes  60 s  period of time equal to 60 seconds  min  
mole  moles  Base SI unit  The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.  mol  
molec  molecs  1/avogadro_constant  molecule , nuc , nucleon  
molecule  molecules  1/avogadro_constant  molec , nuc , nucleon  
month  months  year /12  unit of time defined as the average length of time for a calendar month  
nautical_mile  nautical_miles  1852 m  unit of distance at sea, set at 1852 meters (approximately one minute of arc measured along any meridian) (Unit is temporarily accepted for use with the SI.)  
newton  newtons  m .kg /s ^2  unit of force; the amount needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared (SI derived unit)  N  
nit  nits  1 cd /m ^2  unit of illumination (exact)  nt  
nmile  nmiles  nautical_mile  unit of length in the US Customary System, equal to 6,076 feet; typically used for air and sea navigation  
nuc  nucs  1/avogadro_constant  molec , molecule , nucleon  
nucleon  nucleons  1/avogadro_constant  molec , molecule , nuc  
octet  octets  8  byte  
oersted  oersteds  7.957747e1 A /m  unit of electricity/magnetism  Oe  
ohm  ohms  V /A  standard unit of electrical resistance; the resistance between two points of a conductor when a constant potential difference of 1.0 volt, applied to these points, produces in the conductor a current of 1.0 ampere (SI derived unit)  Ω , Ω  
ounce_force  ounces_force  2.780139e1 N  unit of force, equal to the magnitude of the force exerted by one ounce of mass in a 9.80665 m/s2 gravitational field (exact)  ozf  force_ounce 
parsec  parsecs  3.085678e16 m  unit of length corresponding to the distance at which the mean radius of the earth’s orbit subtends an angle of one second of arc, a typical lengthscale of astronomy  
pascal  pascals  N /m ^2  unit of pressure (force per unit area) equal to one newton per square meter (SI derived unit)  Pa  
peck  pecks  bushel /4  unit of volume defined as 537.6 cubic inches in the US Customary system (and formerly in England), where it is used as a dry measure (exact)  pk  
pennyweight  pennyweights  1.555174e3 kg  unit of mass; based on historical US troy weight system (is 1/20 troy ounce)  
percent  0.01  number of parts per hundred (Constant)  %  
perch  perches  16.5 US_survey_feet  unit of length equal to onefourth of a surveyor’s chain  pole , rod  
perm_0C  perms_0C  5.72135e11 kg /(Pa .s .m ^2)  unit of mass per unit time (includes flow) for how fast water vapor flows through substance, or permeance; equals 1 gram of water vapor per hour, per square meter, per millimeter of mercury at 0 degrees C  
perm_23C  perms_23C  5.74525e11 kg /(Pa .s .m ^2)  unit of mass per unit time for how fast water vapor flows through substance, or permeance; equals 1 gram of water vapor per hour, per square meter, per millimeter of mercury at 23 degrees C  
phot  phots  1e4 lm /m ^2  unit of illumination (exact)  ph  
physical_faraday  physical_faradays  9.65219e4 C  unit of electricity/magnetism  
pi  3.141592653589793238462643383279  mathematical constant equal to the ratio of a circle’s circumference to its diameter (This “unit” is useful in the definition of subsequent units.)  π  
pica  picas  12 printers_point  unit of length equal to 1/6 inch (12 printers points)  printers_pica  
pint  pints  US_liquid_gallon /8  unit of volume for liquid measure in the US Customary system, equal to 1/8 liquid gallon (exact)  pt  US_liquid_pint , liquid_pint 
poise  poises  1e1 Pa .s  unit of dynamic viscosity, corresponding to 0.1 pascalsecond (pascalsecond: a fluid placed between two plates, when one plate is pushed sideways with a shear stress of one pascal, moves a distance equal to the thickness of the layer between the plates in one second) (exact)  
pole  poles  16.5 US_survey_feet  unit of length equal to onefourth of a surveyor’s chain  perch , rod  
pond  ponds  9.806650e3 N  unit of force, equal to the magnitude of the force exerted by one gram of mass in a 9.80665 m/s2 gravitational field (exact)  
potential_vorticity_unit  potential_vorticity_units  1e6 m ^2 s ^1 K kg ^1  (exact)  PVU  
pound  pounds  4.5359237e1 kg  unit of mass in avoirdupois system of weights (a system commonly used in United States)  lb  avoirdupois_pound 
pound_force  pounds_force  4.4482216152605 N  unit of force, equal to the magnitude of the force exerted by one pound of mass in a 9.80665 m/s2 gravitational field (exact)  lbf  force_pound 
poundal  poundals  1.382550e1 N  unit of force, that which is necessary to accelerate 1 poundmass to 1 foot per second per second (exact)  
printers_pica  printers_picas  12 printers_point  unit of length equal to 1/6 inch (12 printers points)  pica  
printers_point  printers_points  3.514598e4 m  unit of length equal to 1/72.27 inch, the original (standardized 1886) unit for measuring font size and other small items on a printed page (see also big_point)  
quart  quarts  US_liquid_gallon /4  unit of volume for liquid measure in the US Customary system, equal to 1/4 liquid gallon (exact)  US_liquid_quart , liquid_quart  
radian  radians  Dimensionless quantity  standard unit of angular measure, an angle that creates an arc in a circle equal in length to that circle’s radius (roughly 57.3 degrees); as a ratio of two lengths, it has no dimension (SI derived unit)  rad  
refrigeration_ton  refrigeration_tons  12000 Btu /hr  unit of power describing the heatextraction capacity of cooling equipment; defined as the heat absorbed by melting 1 short ton of pure ice at 0 degrees C in 24 hours  ton_of_refrigeration  
register_ton  register_tons  2.831685 m ^3  unit of volume used for internal capacity of ships, equal to 100 cubic feet  
rem  rems  cSv  unit of radiation dosage applied to humans; equal to one hundredth of a sievert (Unit is temporarily accepted for use with the SI.)  
revolution  revolutions  2 pi rad  unit of angle in a plane signifying a full 360degree circle  circle , cycle , rotation , turn  
rhe  rhes  10/(Pa .s )  unit of fluidity (reciprocal of velocity), measured in reciprocal poise (exact)  
rod  rods  16.5 US_survey_feet  unit of length equal to onefourth of a surveyor’s chain  perch , pole  
roentgen  roentgens  2.58e4 C /kg  unit of ionizing radiation, the amount producing one electrostatic unit of positive or negative ionic charge in one cubic centimeter of air under standard conditions; rarely used (Unit is temporarily accepted for use with the SI.)  R  
rotation  rotations  2 pi rad  unit of angle in a plane signifying a full 360degree circle  circle , cycle , revolution , turn  
rotation_per_second  rotations_per_second  rotation /second  unit of angular velocity (exact)  cps , rps  
scruple  scruples  20 grain  unit of mass in apothecaries’ weight system (is 1/3 apdram)  
sec  secs  s  unit of time, synonym for second (Synonym for SI unit)  
second  seconds  Base SI unit  The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.  s  
shaft_horsepower  shaft_horsepowers  7.456999e2 W  unit of power originally corresponding to the estimated typical power of draft horses, calculated as lifting 33000 pounds one foot in one minute (550 footpounds/second) (shaft_horsepower is a unit of power as delivered by a drive shaft at its output (e.g., of a ship, aircraft engine, or helicopter rotor; typically not automobiles due to drive train losses))  hp  horsepower 
shake  shakes  1e8 s  unit of time approximating the lifetime of an individual neutron, useful for describing very brief durations, e.g., in nuclear physics  
short_hundredweight  short_hundredweights  4.535924e1 kg  unit of mass, a US hundredweight, which is 100 pounds  
short_ton  short_tons  2000 pound  unit of mass based on US weight system  ton  
sidereal_day  sidereal_days  8.616409e4 s  unit of time that it takes the earth to complete one revolution with respect to a star, roughly 23 hours, 56 minutes, 4 seconds  
sidereal_hour  sidereal_hours  3.590170e3 s  unit of time equal to 1/24 sidereal day  
sidereal_minute  sidereal_minutes  5.983617e1 s  unit of time equal to 1/60 sidereal hour  
sidereal_month  sidereal_months  27.321661 day  unit of time based on 1/12 of the sidereal year  
sidereal_second  sidereal_seconds  0.9972696 s  unit of time equal to 1/60 sidereal second  
sidereal_year  sidereal_years  3.155815e7 s  unit of time for the earth to make one complete revolution around the sun, relative to the fixed stars  
siemens  siemenses  A /V  unit of electric conductance; the reciprocal of one ohm (SI derived unit)  S  
sievert  sieverts  J /kg  unit of ionizing radiation dose, measuring the health effect of low levels of ionizing radiation on the human body (SI derived unit with special names/symbols admitted for reasons of safeguarding human health)  Sv  
slug  slugs  14.59390 kg  unit of mass associated with Imperial units; a mass that accelerates by 1 ft/s2 when a force of one poundforce (lbF) is exerted on it  
standard_atmosphere  standard_atmospheres  1.01325e5 Pa  unit of pressure, an international reference pressure intended to represent the mean atmospheric pressure at mean sea level at the latitude of Paris, France (exact)  atm  atmosphere 
standard_free_fall  standard_free_falls  9.806650 m /s ^2  unit of acceleration corresponding to the nominal gravitational acceleration of an object in a vacuum near the surface of earth (exact)  
statampere  statamperes  3.335640e10 A  unit of electricity/magnetism  
statcoulomb  statcoulombs  3.335640e10 C  unit of electricity/magnetism  
statfarad  statfarads  1.112650e12 F  unit of electricity/magnetism  
stathenry  stathenries  8.987554e11 H  unit of electricity/magnetism  
statmho  statmhos  1.112650e12 S  unit of electricity/magnetism  
statohm  statohms  8.987554e11 ohm  unit of electricity/magnetism  
statvolt  statvolts  2.997925e2 V  unit of electricity/magnetism  
steradian  steradians  rad ^2  standard unit of solid angle measure, it is the solid angle which cuts out an area on a sphere that is the square of the sphere’s radius; as a ratio of two areas, it has no dimension (SI derived unit)  sr  
stere  steres  1 m ^3  unit of volume equal to a cubic meter, originally defined primarily as a measure for firewood (exact)  
stilb  stilbs  1e4 cd /m ^2  unit of illumination (exact)  sb  
stokes  stokeses  1e4 m ^2/s  unit of kinematic viscosity, measuring the ratio of the dynamic viscosity to the density of the fluid; water at 20 degrees C has a kinematic viscosity about 100 stokes, or more cmomonly, 1 cSt (exact)  St  
sverdrup  sverdrups  1e6 m ^3/s  unit of volume transport, used almost exclusively to measure the volumetric rate of ocean currents (exact)  
tablespoon  tablespoons  US_fluid_ounce /2  unit of volume for liquid measure in the US Customary system, equal to 1/2 liquid ounce (exact)  Tbl , Tblsp , Tbsp , tblsp , tbsp  
teaspoon  teaspoons  tablespoon /3  unit of volume defined as 1/3 tablespoon, the actual volume of which can vary depending on the measurement system (but is based on the US Customary system in this database) (exact)  tsp  
technical_atmosphere  technical_atmospheres  1 kg gravity /cm 2  unit of pressure equal to one kilogram force per square centimeter (exact; note that the symbol ‘at’ clashes with that of the katal (‘kat’), the SI unit of catalytic activity)  at  
tesla  teslas  Wb /m ^2  unit of flux density, equal to one weber per square meter (SI derived unit)  T  
tex  texes  1e6 kg /m  unit of lineic mass density for fibers, defined as mass in grams per 1000 meters (more common in Canada and Continental Europe) (exact)  
therm  therms  1.054804e8 J  unit of energy legally defined in the U.S. Federal Register of July 27, 1968, and the legal unit used by the U.S. natural gas industry (exact)  thm  US_therm 
thermochemical_calorie  thermochemical_calories  4.184000 J  unit of heat energy defined as 4.184 Joules exactly (International Standard ISO 314: Quantities and units, Part 4: Heat); approximately the energy needed to increase the temperature of 1 gram of water by 1 C (exact)  
TNT  4.184 MJ /kg  unit of energy; approximately the energy released by the detonation of a given amount of mass of TNT (by definition)  
ton  tons  2000 pound  unit of mass based on US weight system  short_ton  
ton_force  tons_force  2000 force_pound  unit of force, equal to the magnitude of the force exerted by one ton of mass in a 9.80665 m/s2 gravitational field (specifically a short ton of mass) (exact)  force_ton  
ton_of_refrigeration  tons_of_refrigeration  12000 Btu /hr  unit of power describing the heatextraction capacity of cooling equipment; defined as the heat absorbed by melting 1 short ton of pure ice at 0 degrees C in 24 hours  refrigeration_ton  
ton_TNT  tons_TNT  4.184e9 J  unit of energy; approximately the energy released by the detonation of a 1000 kilograms of TNT (by definition)  
tonne  tonnes  1000 kg  unit of weight equal to 1000 kilograms  t  metric_ton 
torr  torrs  mm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 mm height at 0 degrees C; approximately (within 0.000015%, generally below measurement error) 1 Torr, which is 1/760 standard atmospheric pressure  mmHg , mm_Hg , mm_hg , mmhg  millimeter_Hg 
tropical_month  tropical_months  27.321582 day  unit of time based on 1/12 of the tropical year  
tropical_year  tropical_years  3.15569259747e7 s  unit of time; Interval between 2 successive passages of sun through vernal equinox (365.242198781 days). See http://www.ast.cam.ac.uk/pubinfo/leaflets/, http://aa.usno.navy.mil/AA/, and http://adswww.colorado.edu/adswww/astro_coord.html  yr  year 
troy_ounce  troy_ounces  3.110348e2 kg  unit of mass; based on historical US troy weight system (is 1/12 troy pound)  apothecary_ounce  
troy_pound  troy_pounds  3.732417e1 kg  unit of mass; based on historical US troy weight system (is 5760 grain)  apothecary_pound  
turn  turns  2 pi rad  unit of angle in a plane signifying a full 360degree circle  circle , cycle , revolution , rotation  
UK_fluid_ounce  UK_fluid_ounces  UK_liquid_gallon /160  unit of volume for liquid measure in the Imperial system, equal to 1/160 liquid gallon (exact)  UK_liquid_ounce  
UK_horsepower  UK_horsepowers  7.4570e2 W  unit of power originally corresponding to the estimated typical power of draft horses, calculated as lifting 33000 pounds one foot in one minute (550 footpounds/second), as calculated/specified in the United Kingdom  
UK_liquid_cup  UK_liquid_cups  UK_liquid_gallon /16  unit of volume for liquid measure in the Imperial system, equal to 1/16 liquid gallon (exact)  
UK_liquid_gallon  UK_liquid_gallons  4.546090e3 m ^3  unit of volume for liquid measure in the Imperial system (exact)  
UK_liquid_gill  UK_liquid_gills  UK_liquid_gallon /32  unit of volume for liquid measure in the Imperial system, equal to 1/32 liquid gallon (exact)  
UK_liquid_ounce  UK_liquid_ounces  UK_liquid_gallon /160  unit of volume for liquid measure in the Imperial system, equal to 1/160 liquid gallon (exact)  UK_fluid_ounce  
UK_liquid_pint  UK_liquid_pints  UK_liquid_gallon /8  unit of volume for liquid measure in the Imperial system, equal to 1/8 liquid gallon (exact)  
UK_liquid_quart  UK_liquid_quarts  UK_liquid_gallon /4  unit of volume for liquid measure in the Imperial system, equal to 1/4 liquid gallon (exact)  
unified_atomic_mass_unit  unified_atomic_mass_units  1.6605402e27 kg  standard unit for indicating mass on an atomic or molecular scale; is approximately the mass of one nucleon (either a single proton or neutron), and equivalent to 1 g/mol (Unit’s value is obtained experimentally)  u  amu , atomic_mass_unit , atomicmassunit 
unit_pole  unit_poles  1.256637e7 Wb  unit of electricity/magnetism  
US_dry_gallon  US_dry_gallons  4.404884e3 m ^3  unit of volume for dry measure in the US Customary system, defined as 1/2 peck or 1/8 bushel  
US_dry_pint  US_dry_pints  US_dry_gallon /8  unit of volume for dry measure in the US Customary system, equal to 1/2 US dry quart (exact)  dry_pint  
US_dry_quart  US_dry_quarts  US_dry_gallon /4  unit of volume for dry measure in the US Customary system, equal to 1/32 US bushel (exact)  dry_quart  
US_fluid_ounce  US_fluid_ounces  US_liquid_gallon /128  unit of volume for liquid measure in the US Customary system, equal to 1/128 liquid gallon (exact)  floz , oz  US_liquid_ounce , fluid_ounce , liquid_ounce 
US_liquid_cup  US_liquid_cups  US_liquid_gallon /16  unit of volume for liquid measure in the US Customary system, equal to 1/16 liquid gallon (exact)  cup , liquid_cup  
US_liquid_gallon  US_liquid_gallons  3.785412e3 m ^3  unit of volume for liquid measure in the US Customary system, defined as 3.785412 liters  gallon , liquid_gallon  
US_liquid_gill  US_liquid_gills  US_liquid_gallon /32  unit of volume for liquid measure in the US Customary system, equal to 1/32 liquid gallon (exact)  gill , liquid_gill  
US_liquid_ounce  US_liquid_ounces  US_liquid_gallon /128  unit of volume for liquid measure in the US Customary system, equal to 1/128 liquid gallon (exact)  floz , oz  US_fluid_ounce , fluid_ounce , liquid_ounce 
US_liquid_pint  US_liquid_pints  US_liquid_gallon /8  unit of volume for liquid measure in the US Customary system, equal to 1/8 liquid gallon (exact)  pt  liquid_pint , pint 
US_liquid_quart  US_liquid_quarts  US_liquid_gallon /4  unit of volume for liquid measure in the US Customary system, equal to 1/4 liquid gallon (exact)  liquid_quart , quart  
US_statute_mile  US_statute_miles  5280 US_survey_feet  unit of length used for earlier survey data in some countries, slightly slightly different than the current international mile  US_survey_mile  
US_survey_foot  US_survey_feet  (1200/3937) m  unit of length used for earlier survey data in some countries, slightly different than the current international foot  
US_survey_mile  US_survey_miles  5280 US_survey_feet  unit of length used for earlier survey data in some countries, slightly slightly different than the current international mile  US_statute_mile  
US_survey_yard  US_survey_yards  3 US_survey_feet  unit of length used in earlier survey data in some countries, slightly different than the current international yard  
US_therm  US_therms  1.054804e8 J  unit of energy legally defined in the U.S. Federal Register of July 27, 1968, and the legal unit used by the U.S. natural gas industry (exact)  thm  therm 
volt  volts  W /A  standard unit of electric potential difference (and electromotive force); the difference of potential between two points of a conductor carrying a constant current of one ampere and dissipating one watt of power (SI derived unit)  V  
voltampere  voltamperes  V .A  unit of electric power equal to the product of one volt and one ampere, equivalent to one watt for direct current systems and a unit of apparent power for alternating current systems (exact)  VA  
water  waters  gravity 1000 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of water (exact)  H2O , h2o  conventional_water 
water_39F (actually 39.2 F)  waters_39F  gravity 999.972 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of water at 4 degrees C  water_4C  
water_4C  waters_4C  gravity 999.972 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of water at 4 degrees C  water_39F  
water_60F  waters_60F  gravity 999.001 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of water at 60 degrees F  
water_horsepower  water_horsepowers  7.46043e2 W  unit of power used in the U.S. primarily in rating pumps; calculated as pump capacity Q (gallons per minute) times pump pressure (“head”) of P (feet of head), divided by 3956 water horsepower; the calculation assumes water density is 8 1/3 pounds per U.S. gallon, which is not exact.  
watt  watts  J /s  standard unit of power, equivalent to one joule per second, and equal to one ampere flowing across a potential difference of one volt (SI derived unit)  W  
watthour  watthours  watt .hour  unit of energy equal to the product of the power in watts and the time in hours (if the energy is being transmitted or used at a constant rate (power) over a period of time); one watt is equal to 1 Joule/second (exact)  
weber  webers  V .s  unit of magnetic flux (product of the average magnetic field times the perpendicular area that it penetrates), expressed as voltseconds (SI derived unit)  Wb  
week  weeks  7 day  unit of time commonly defined as 7 days  
work_month  work_months  work_year /12  (exact)  
work_year  work_years  2056 hours  (exact)  
yard  yards  3 international_feet  unit of length equal to 3 international feet, in the imperial and US customary systems; primarily used in the United States  yd  international_yard 
year  years  3.15569259747e7 s  unit of time; Interval between 2 successive passages of sun through vernal equinox (365.242198781 days). See http://www.ast.cam.ac.uk/pubinfo/leaflets/, http://aa.usno.navy.mil/AA/, and http://adswww.colorado.edu/adswww/astro_coord.html  yr  tropical_year 
ångström  ångströms  1e10 m  unit of length equal to one hundredmillionth of a centimeter (1 meter/10**10) (Unit is temporarily accepted for use with the SI.)  Å , Å  angstrom 
Units by Symbol
Symbol  Formula  Definition  Name(s)  Other Symbols 

“  ‘ /60  measurement of a plane angle equal to 1/60 arc minute  angular_second , arc_second , arcsec , arcsecond  ″ 
%  0.01  number of parts per hundred (Constant)  percent  
‘  ° /60  measurement of a plane angle equal to 1/60 arc degree  angular_minute , arc_minute , arcmin , arcminute  ′ 
a  dam ^2  unit of area equal to 100 square meters (Unit is temporarily accepted for use with the SI.)  are  
A  Base SI unit  The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular crosssection, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2e7 newton per meter of length.  ampere  
at  1 kg gravity /cm 2  unit of pressure equal to one kilogram force per square centimeter (exact; note that the symbol ‘at’ clashes with that of the katal (‘kat’), the SI unit of catalytic activity)  technical_atmosphere  
atm  1.01325e5 Pa  unit of pressure, an international reference pressure intended to represent the mean atmospheric pressure at mean sea level at the latitude of Paris, France (exact)  atmosphere , standard_atmosphere  
b  100 fm ^2  unit of area, approximately the crosssectional area of a uranium nucleus (10e28 square meters) (Unit is temporarily accepted for use with the SI.)  barn  
B_SPL  lg(re 20e6 Pa )  logarithmic unit used to compare the sound pressure of an unknown sound to a standard reference sound pressure; is the base unit for “dB_SPL”, a more typical logarithmic unit for measuring sound pressure (the SI unit for sound pressure is pascal); the standard reference sound pressure in air or other gases is 20 microPascal, which is usually considered the threshold of human hearing (at 1 kHz) (sound pressure level)  
bbl  42 US_liquid_gallon  unit of volume used by US and Canadian petroleum organizations (The following is the definition of the petroleum industry)  barrel  
Bd  Hz  unit of frequency, synonym for hertz (Synonym for SI unit)  baud  bps 
bev  1e9 eV  unit of energy corresponding to 1 billion electron volts (eV) (exact)  
Bm  lg(re 1 mW )  unit of power in decibel scale, referenced to 1 milliwatt; the power in belmilliwatts is equal to 100 times the base 10 logarithm of the power in milliwatts (making decibelmilliwatt, the more common term, 10 times the base 10 log of the power in watts)  
bps  Hz  unit of frequency, synonym for hertz (Synonym for SI unit)  baud  Bd 
Bq (Is an alias because ‘1/s’ is already mapped to ‘hertz’ and ‘Hz’)  1/s  unit of radioactivity; the activity of a quantity of material in which one nucleus decays per second (hence, equivalent to one unit per second) (SI derived unit with special names/symbols admitted for reasons of safeguarding human health)  becquerel  
bu  3.523907e2 m ^3  unit of volume defined as 2150.42 cubic inches or 4 pecks in the US Customary system (and formerly in England), where it is used as a dry measure  bushel  
BV  lg(re 1 V )  unit of electricity/magnetism  
Bv  lg(re 0.775 V )  unit of electricity/magnetism (rms voltage)  
BW  lg(re 1 W )  unit of power in decibel scale, referenced to 1 watt; the power in belwatts is equal to 100 times the base 10 logarithm of the power in watts (making decibelwatt, the more common term, 10 times the base 10 log of the power in watts)  
BZ  lg(re (1e6 m )^3)  logarithmic unit used to compare the reflectivity (Z) of an unknown remote object, to the reflective return created by a droplet of rain with a diameter of 1 mm; is the base unit for “dBz”, which is the typical logarithmic unit for measuring atmospheric radar reflectivity; a value of 0 Bz (0 DBz) corresponds to the return from a single cubic micron; a value of 6 Bz (60 DBz) corresponds to extremely heavy rain.  
BµV (uses MICRO SIGN)  lg(re 1e6 V )  unit of electricity/magnetism  
C  s .A  standard unit of electric charge, the quantity of electricity transported in one second by a current of one ampere (SI derived unit)  coulomb  
cal  4.1868 J  unit of heat energy used in thermochemistry, the International Steam Table (IT) calorie defined by the Fifth International Conference on the properties of Steam (1956) (exact)  IT_calorie , calorie  
cc  cm ^3  unit of volume equal to the volume of a cube 1 centimeter on each side (exact)  
cd  Base SI unit  The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540e12 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.  candela  
Ci  3.7e10 Bq  unit of radioactivity corresponding to 3.7 * 10e10 disintegrations per second (Unit is temporarily accepted for use with the SI.)  curie  
cm_H2O  cm H2O  unit of pressure derived from pressure head calculations using metrology; represents the pressure exerted by a column of water of 1 cm height at 4 degrees C  cmH2O  
cm_Hg  cm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 cm height at 0 degrees C  cmHg  
cmH2O  cm H2O  unit of pressure derived from pressure head calculations using metrology; represents the pressure exerted by a column of water of 1 cm height at 4 degrees C  cm_H2O  
cmHg  cm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 cm height at 0 degrees C  cm_Hg  
cps  rotation /second  unit of angular velocity (exact)  rotation_per_second  rps 
d  24 h  period of time equal to 24 hours  day  
dr  avoirdupois_ounce /16  unit of mass in the avoirdupois system (the system commonly used in the United States) (exact)  dram  
DU  446.2 micromoles /meter ^2  dobson  
e  1.602176487e19 C  unit of electricity/magnetism  
eV  1.60217733e19 J  unit of energy equal to the work accelerating an electron through a potential difference of one volt (Unit’s value is obtained experimentally)  electron_volt , electronvolt  
F  C /V  standard unit of capacitance; the amount which, when a capacitor is charged to a potential difference of one volt, carries a charge of one coulomb (SI derived unit)  farad  
fldr  US_fluid_ounce /8  unit of volume for liquid measure in the apothecary system, equal to 1/8 liquid ounce (exact)  fluid_dram  
floz  US_liquid_gallon /128  unit of volume for liquid measure in the US Customary system, equal to 1/128 liquid gallon (exact)  US_fluid_ounce , US_liquid_ounce , fluid_ounce , liquid_ounce  oz 
ft  12 international_inches  unit of length equal to 12 international inches, in the imperial and US customary systems; primarily used in the United States  foot , international_foot  
ftH2O  foot water  unit of pressure representing the pressure exerted by a column of water of 1 foot height at 4 degrees C  footH2O , foot_H2O , foot_water  fth2o 
fth2o  foot water  unit of pressure representing the pressure exerted by a column of water of 1 foot height at 4 degrees C  footH2O , foot_H2O , foot_water  ftH2O 
g  1e3 kg  unit of mass equal to one thousandth of a kilogram (SI derived unit)  gram  
gf  gram force  unit of force, equal to the magnitude of the force exerted by one gram of mass in a 9.80665 m/s2 gravitational field (exact)  force_gram , gram_force  
gp  gravity  (exact)  dynamic , geopotential  
gr  6.479891e5 kg  unit of mass equal to 1/7000 pound  grain  
Gy  J /kg  unit of ionizing radiation, a measure of the absorbed dose of radiation; absorption of one joule of radiation energy by one kilogram of matter (SI derived unit with special names/symbols admitted for reasons of safeguarding human health)  gray  
h  60 min  period of time equal to 60 minutes  hour  hr 
H  Wb /A  unit of inductance; where a circuit’s current changes at a constant rate of 1 ampere per second, results in a generation of 1 V of potential difference (SI derived unit)  henry  
h2o  gravity 1000 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of water (exact)  conventional_water , water  H2O 
H2O  gravity 1000 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of water (exact)  conventional_water , water  h2o 
Hg  gravity 13595.10 kg /m ^3  specifies the acceleration at the earth’s surface of a substance with the density of mercury at 0 degrees C  conventional_mercury , mercury_0C , mercury_32F  
hp  7.456999e2 W  unit of power originally corresponding to the estimated typical power of draft horses, calculated as lifting 33000 pounds one foot in one minute (550 footpounds/second) (shaft_horsepower is a unit of power as delivered by a drive shaft at its output (e.g., of a ship, aircraft engine, or helicopter rotor; typically not automobiles due to drive train losses))  horsepower , shaft_horsepower  
hr  60 min  period of time equal to 60 minutes  hour  h 
Hz  1/s  unit of frequency meaning one cycle per second (SI derived unit)  hertz  
in  2.54 cm  unit of length equal to 25.4 mm by definition, used in imperial and US customary systems  inch , international_inch  
in_Hg  inch Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 inch height at 0 degrees C  inch_Hg  inHg 
inHg  inch Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 inch height at 0 degrees C  inch_Hg  in_Hg 
J  N .m  standard unit of work or energy, equal to the work done by a force of one newton acting along a distance of one meter (SI derived unit)  joule  
K  Base SI unit  The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.  kelvin  
kat  mol /s  unit of catalytic activity (property of a catalyst, such as an enzyme); expresses the ability to break 1 mole of bonds per second under specified conditions (SI derived unit)  katal  
kg  Base SI unit  The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.  kilogram  
kgf  9.806650 N  unit of force, equal to the magnitude of the force exerted by one kilogram of mass in a 9.80665 m/s2 gravitational field (exact)  force_kilogram , kilogram_force  
ksi  kip /in ^2  unit of pressure representing the pressure exerted, due to gravity, by a 1000pound mass, of area one square inch (exact)  
kt  knot  unit of speed, synonym for nautical_mile/hour (Synonym for SI unit)  kts  
kts  knot  unit of speed, synonym for nautical_mile/hour (Synonym for SI unit)  kt  
L (NIST recommendation)  dm ^3  unit of capacity equal to 1000 cubic centimeters (The definition is exact. From 1901 to 1964, however, 1 liter was 1.000028 dm^3 (volume of 1 kg of water under standard conditions).)  liter , litre  l 
l  dm ^3  unit of capacity equal to 1000 cubic centimeters (The definition is exact. From 1901 to 1964, however, 1 liter was 1.000028 dm^3 (volume of 1 kg of water under standard conditions).)  liter , litre  L 
lb  4.5359237e1 kg  unit of mass in avoirdupois system of weights (a system commonly used in United States)  avoirdupois_pound , pound  
lbf  4.4482216152605 N  unit of force, equal to the magnitude of the force exerted by one pound of mass in a 9.80665 m/s2 gravitational field (exact)  force_pound , pound_force  
lm  cd .sr  unit of luminous flux, a measure of the total “amount” of visible light emitted by a source; one candelasteradian (SI derived unit)  lumen  
lx  lm /m ^2  unit of illuminance and luminous emittance, measuring luminous flux per unit area, and used as a measure of intensity of light; equal to one lumen per square meter (SI derived unit)  lux  
m  Base SI unit  The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.  meter , metre  
mi  5280 international_feet  unit of length equal to 5280 feet, equal to 12 international inches, in the imperial and US customary systems; primarily used in the United States and other smaller countries with ties to the US or United Kingdom  international_mile , mile  
min  60 s  period of time equal to 60 seconds  minute  
mm_Hg  mm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 mm height at 0 degrees C; approximately (within 0.000015%, generally below measurement error) 1 Torr, which is 1/760 standard atmospheric pressure  millimeter_Hg , torr  mmHg , mm_hg , mmhg 
mm_hg  mm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 mm height at 0 degrees C; approximately (within 0.000015%, generally below measurement error) 1 Torr, which is 1/760 standard atmospheric pressure  millimeter_Hg , torr  mmHg , mm_Hg , mmhg 
mmhg  mm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 mm height at 0 degrees C; approximately (within 0.000015%, generally below measurement error) 1 Torr, which is 1/760 standard atmospheric pressure  millimeter_Hg , torr  mmHg , mm_Hg , mm_hg 
mmHg  mm Hg  unit of pressure representing the pressure exerted by a column of mercury of 1 mm height at 0 degrees C; approximately (within 0.000015%, generally below measurement error) 1 Torr, which is 1/760 standard atmospheric pressure  millimeter_Hg , torr  mm_Hg , mm_hg , mmhg 
mol  Base SI unit  The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.  mole  
N  m .kg /s ^2  unit of force; the amount needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared (SI derived unit)  newton  
nt  1 cd /m ^2  unit of illumination (exact)  nit  
Oe  7.957747e1 A /m  unit of electricity/magnetism  oersted  
oz  US_liquid_gallon /128  unit of volume for liquid measure in the US Customary system, equal to 1/128 liquid gallon (exact)  US_fluid_ounce , US_liquid_ounce , fluid_ounce , liquid_ounce  floz 
ozf  2.780139e1 N  unit of force, equal to the magnitude of the force exerted by one ounce of mass in a 9.80665 m/s2 gravitational field (exact)  force_ounce , ounce_force  
Pa  N /m ^2  unit of pressure (force per unit area) equal to one newton per square meter (SI derived unit)  pascal  
ph  1e4 lm /m ^2  unit of illumination (exact)  phot  
pk  bushel /4  unit of volume defined as 537.6 cubic inches in the US Customary system (and formerly in England), where it is used as a dry measure (exact)  peck  
ppb  1e9  parts per billion (Constant)  ppbv  
ppbv  1e9  parts per billion (Constant)  ppb  
ppm  1e6  parts per million (Constant)  ppmv  
ppmv  1e6  parts per million (Constant)  ppm  
ppq  1e15  parts per quadrillion (Constant)  ppqv  
ppqv  1e15  parts per quadrillion (Constant)  ppq  
ppt  1e12  parts per trillion (Constant)  pptv  
pptv  1e12  parts per trillion (Constant)  ppt  
psi  1 pound gravity /in ^2  unit of pressure representing the pressure exerted, due to gravity, by a onepound mass, of area one square inch; commonly referred to as “pounds per square inch” (exact)  
pt  US_liquid_gallon /8  unit of volume for liquid measure in the US Customary system, equal to 1/8 liquid gallon (exact)  US_liquid_pint , liquid_pint , pint  
PVU  1e6 m ^2 s ^1 K kg ^1  (exact)  potential_vorticity_unit  
R  2.58e4 C /kg  unit of ionizing radiation, the amount producing one electrostatic unit of positive or negative ionic charge in one cubic centimeter of air under standard conditions; rarely used (Unit is temporarily accepted for use with the SI.)  roentgen  
rad  Dimensionless quantity  standard unit of angular measure, an angle that creates an arc in a circle equal in length to that circle’s radius (roughly 57.3 degrees); as a ratio of two lengths, it has no dimension (SI derived unit)  radian  
rpm  rotation /minute  unit of angular velocity measuring the angular distance covered by a rotating object, divided by the amount of time used to cover that distance; measured perpendicular to the plane of rotation, with direction usually indicated by the righthand rule (exact)  
rps  rotation /second  unit of angular velocity (exact)  rotation_per_second  cps 
s  Base SI unit  The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.  second  
S  A /V  unit of electric conductance; the reciprocal of one ohm (SI derived unit)  siemens  
sb  1e4 cd /m ^2  unit of illumination (exact)  stilb  
sr  rad ^2  standard unit of solid angle measure, it is the solid angle which cuts out an area on a sphere that is the square of the sphere’s radius; as a ratio of two areas, it has no dimension (SI derived unit)  steradian  
St  1e4 m ^2/s  unit of kinematic viscosity, measuring the ratio of the dynamic viscosity to the density of the fluid; water at 20 degrees C has a kinematic viscosity about 100 stokes, or more cmomonly, 1 cSt (exact)  stokes  
Sv  J /kg  unit of ionizing radiation dose, measuring the health effect of low levels of ionizing radiation on the human body (SI derived unit with special names/symbols admitted for reasons of safeguarding human health)  sievert  
t  1000 kg  unit of weight equal to 1000 kilograms  metric_ton , tonne  
T  Wb /m ^2  unit of flux density, equal to one weber per square meter (SI derived unit)  tesla  
Tbl  US_fluid_ounce /2  unit of volume for liquid measure in the US Customary system, equal to 1/2 liquid ounce (exact)  tablespoon  Tblsp , Tbsp , tblsp , tbsp 
tblsp  US_fluid_ounce /2  unit of volume for liquid measure in the US Customary system, equal to 1/2 liquid ounce (exact)  tablespoon  Tbl , Tblsp , Tbsp , tbsp 
Tblsp  US_fluid_ounce /2  unit of volume for liquid measure in the US Customary system, equal to 1/2 liquid ounce (exact)  tablespoon  Tbl , Tbsp , tblsp , tbsp 
tbsp  US_fluid_ounce /2  unit of volume for liquid measure in the US Customary system, equal to 1/2 liquid ounce (exact)  tablespoon  Tbl , Tblsp , Tbsp , tblsp 
Tbsp  US_fluid_ounce /2  unit of volume for liquid measure in the US Customary system, equal to 1/2 liquid ounce (exact)  tablespoon  Tbl , Tblsp , tblsp , tbsp 
thm  1.054804e8 J  unit of energy legally defined in the U.S. Federal Register of July 27, 1968, and the legal unit used by the U.S. natural gas industry (exact)  US_therm , therm  
tsp  tablespoon /3  unit of volume defined as 1/3 tablespoon, the actual volume of which can vary depending on the measurement system (but is based on the US Customary system in this database) (exact)  teaspoon  
u  1.6605402e27 kg  standard unit for indicating mass on an atomic or molecular scale; is approximately the mass of one nucleon (either a single proton or neutron), and equivalent to 1 g/mol (Unit’s value is obtained experimentally)  amu , atomic_mass_unit , atomicmassunit , unified_atomic_mass_unit  
ua  1.495979e11 m  unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun (Unit’s value is obtained experimentally)  astronomical_unit  
V  W /A  standard unit of electric potential difference (and electromotive force); the difference of potential between two points of a conductor carrying a constant current of one ampere and dissipating one watt of power (SI derived unit)  volt  
VA  V .A  unit of electric power equal to the product of one volt and one ampere, equivalent to one watt for direct current systems and a unit of apparent power for alternating current systems (exact)  voltampere  
W  J /s  standard unit of power, equivalent to one joule per second, and equal to one ampere flowing across a potential difference of one volt (SI derived unit)  watt  
Wb  V .s  unit of magnetic flux (product of the average magnetic field times the perpendicular area that it penetrates), expressed as voltseconds (SI derived unit)  weber  
yd  3 international_feet  unit of length equal to 3 international feet, in the imperial and US customary systems; primarily used in the United States  international_yard , yard  
yr  3.15569259747e7 s  unit of time; Interval between 2 successive passages of sun through vernal equinox (365.242198781 days). See http://www.ast.cam.ac.uk/pubinfo/leaflets/, http://aa.usno.navy.mil/AA/, and http://adswww.colorado.edu/adswww/astro_coord.html  tropical_year , year  
° (DEGREE SIGN)  (pi /180) rad  measurement of a plane angle representing 1/360 of a full rotation  angular_degree , arc_degree , arcdeg , degree  
°C (DEGREE SIGN)  K @ 273.15  unit (and scale) of temperature, with same magnitude as the kelvin and a zeropoint offset of 273.15 (SI derived unit)  degree_Celsius  
°F (DEGREE SIGN)  °R @ 459.67  unit of thermodynamic temperature  degF , deg_F , degreeF , degree_F , degree_fahrenheit , fahrenheit  ℉ 
°K (DEGREE SIGN)  K  unit of temperature, synonym for kelvin (Synonym for SI unit)  degK , deg_K , degreeK , degree_K , degree_kelvin  
°R (DEGREE SIGN)  K /1.8  unit of thermodynamic temperature  degR , deg_R , degreeR , degree_R , degree_rankine  
Å (LATIN CAPITAL LETTER A WITH RING ABOVE)  1e10 m  unit of length equal to one hundredmillionth of a centimeter (1 meter/10**10) (Unit is temporarily accepted for use with the SI.)  ångström , angstrom  Å 
Å (ANGSTROM SIGN)  1e10 m  unit of length equal to one hundredmillionth of a centimeter (1 meter/10**10) (Unit is temporarily accepted for use with the SI.)  ångström , angstrom  Å 
π (GREEK SMALL LETTER PI)  3.141592653589793238462643383279  mathematical constant equal to the ratio of a circle’s circumference to its diameter (This “unit” is useful in the definition of subsequent units.)  pi  
Ω (OHM SIGN)  V /A  standard unit of electrical resistance; the resistance between two points of a conductor when a constant potential difference of 1.0 volt, applied to these points, produces in the conductor a current of 1.0 ampere (SI derived unit)  ohm  Ω 
Ω (Greek capital letter omega (preferred))  V /A  standard unit of electrical resistance; the resistance between two points of a conductor when a constant potential difference of 1.0 volt, applied to these points, produces in the conductor a current of 1.0 ampere (SI derived unit)  ohm  Ω 
′ (PRIME)  ° /60  measurement of a plane angle equal to 1/60 arc degree  angular_minute , arc_minute , arcmin , arcminute  ‘ 
″ (DOUBLE PRIME)  ‘ /60  measurement of a plane angle equal to 1/60 arc minute  angular_second , arc_second , arcsec , arcsecond  “ 
℃ (DEGREE CELSIUS)  degree_Celsius  unit of temperature, synonym for ‘K @ 273.15’ (degree_Celsius) (Synonym for SI unit)  celsius , degC , deg_C , degreeC , degree_C  
℉ (DEGREE FAHRENHEIT)  °R @ 459.67  unit of thermodynamic temperature  degF , deg_F , degreeF , degree_F , degree_fahrenheit , fahrenheit  °F 
Unit Prefixes
Prefix  Definition  Symbol(s)  Comments 

yotta  1e24  Y 

zetta  1e21  Z 

exa  1e18  E 

peta  1e15  P 

tera  1e12  T 

giga  1e9  G 

mega  1e6  M 

kilo  1e3  k 

hecto  100  h 

deka  10  da 

deci  .1  d 

centi  .01  c 

milli  1e3  m 

micro  1e6  µ μ u 
MICRO SIGN Greek small letter ‘mu’ 
nano  1e9  n 

pico  1e12  p 

femto  1e15  f 

atto  1e18  a 

zepto  1e21  z 

yocto  1e24  y 