formula.expert

Every unit, defined

350 units across 78 quantities. Each page says what the unit is, whether its conversion is exact or measured, where it came from, and which definition this site uses when more than one is in circulation.

Length, area & volume

Length — 17 units
femtometerpicometernanometermicrometermillimetercentimeterdecimetermeterkilometerinchfootyardmilenautical mileastronomical unitlight-yearparsec

Area — 10 units
square millimetersquare centimetersquare meterhectaresquare kilometersquare inchsquare footsquare yardacresquare mile

Volume — 13 units
millilitercentiliterlitercubic metercubic inchcubic footUS fluid ounceUS pintUS quartUS gallonimperial galloncubic yardacre-foot

Section modulus — 4 units
cubic metercubic centimetercubic millimetercubic inch

Area moment of inertia — 5 units
meter to the fourthcentimeter to the fourthmillimeter to the fourthinch to the fourthfoot to the fourth

Mass, density & flow

Mass — 11 units
microgrammilligramgramkilogrammetric tonneouncepoundstoneUS short tongrainunified atomic mass unit (dalton)

Density — 6 units
kilogram per cubic metergram per cubic centimetergram per milliliterkilogram per literpound per cubic footpound per US gallon

Unit weight — 3 units
newton per cubic meterkilonewton per cubic meterpound-force per cubic foot

Linear mass density — 4 units
kilogram per metergram per metergram per centimeterpound per foot

Mass flow rate — 10 units
kilogram per secondkilogram per hourkilogram per daygram per secondpound per hourpound per daytonne per hourkilogram per yearpound per yeartonne per year

Volumetric flow rate — 9 units
cubic meter per secondliter per secondliter per minutecubic meter per hourUS gallon per minutecubic foot per minuteliter per dayUS gallon per daymillion US gallons per day

Molar volume — 4 units
cubic meter per moleliter per molecubic centimeter per molecubic foot per pound-mole

Time, speed & motion

Time — 7 units
millisecondsecondminutehourdayweekyear

Frequency — 7 units
hertzkilohertzmegahertzgigahertzrevolution per minuteper hourper day

Speed — 10 units
meter per secondkilometer per hourfoot per secondmile per hourknotfoot per minutecentimeter per secondmeter per hourmeter per dayfoot per day

Acceleration — 3 units
meter per second squaredfoot per second squaredstandard gravity

Angle — 6 units
radiandegreegradianrevolutionarcminutearcsecond

Angular speed — 4 units
radian per seconddegree per secondrevolution per secondrevolution per minute

Angular acceleration — 3 units
radian per second squareddegree per second squaredrevolution per second squared

Diffusivity — 6 units
square meter per secondsquare millimeter per secondsquare centimeter per secondsquare meter per yearsquare foot per hourcentistokes

Force, pressure & mechanics

Force — 5 units
newtonkilonewtondynepound-forcekilogram-force

Pressure — 12 units
pascalkilopascalmegapascalbaratmospheremillimeter of mercurypound per square inchfoot of water columngigapascalkip per square inchinch of mercuryinch of water column

Torque — 4 units
newton meterkilonewton meterfoot pound-forceinch pound-force

Momentum — 4 units
kilogram meter per secondnewton secondpound foot per secondpound-force second

Moment of inertia — 3 units
kilogram square metergram square centimeterpound square foot

Angular momentum — 2 units
kilogram square meter per secondjoule second

Spring constant — 5 units
newton per meternewton per centimeterkilonewton per meterpound-force per inchpound-force per foot

Surface tension — 4 units
newton per metermillinewton per meterdyne per centimeterpound-force per foot

Energy & power

Energy — 12 units
joulekilojoulemegajoulecaloriekilocaloriewatt-hourkilowatt-hourBritish thermal unitfoot-poundelectron voltkiloelectron voltmegaelectron volt

Power — 7 units
milliwattwattkilowattmegawatthorsepower (mechanical)BTU per hourton of refrigeration

Heat capacity — 3 units
joule per kelvinkilojoule per kelvinBTU per Fahrenheit degree

Molar energy — 3 units
joule per molekilojoule per molekilocalorie per mole

Heat & temperature

Temperature — 4 units
kelvindegree Celsiusdegree Fahrenheitdegree Rankine

Temperature difference — 3 units
kelvin (difference)Celsius degree (difference)Fahrenheit degree (difference)

Specific heat capacity — 4 units
joule per kilogram-kelvinkilojoule per kilogram-kelvincalorie per gram-CelsiusBTU per pound-Fahrenheit

Specific latent heat — 4 units
joule per kilogramkilojoule per kilogramcalorie per gramBTU per pound

Thermal conductivity — 2 units
watt per meter-kelvinBTU per hour-foot-Fahrenheit

Heat transfer coefficient — 3 units
watt per square meter kelvinkilowatt per square meter kelvinBTU per hour square foot Fahrenheit

Thermal resistance — 2 units
kelvin per wattFahrenheit hour per BTU

Areal thermal resistance — 2 units
square meter kelvin per watthour square foot Fahrenheit per BTU

Thermal conductance — 3 units
watt per kelvinkilowatt per kelvinBTU per hour Fahrenheit

Thermal expansion coefficient — 3 units
per kelvinper Celsius degreeper Fahrenheit degree

Humidity ratio — 3 units
kilogram per kilogramgram per kilogramgrain per pound of dry air

Electricity & magnetism

Voltage — 4 units
microvoltmillivoltvoltkilovolt

Electric current — 4 units
microamperemilliampereamperekiloampere

Electric charge — 6 units
microcoulombmillicoulombcoulombmilliampere-hourampere-hourelementary charge

Resistance — 4 units
milliohmohmkiloohmmegaohm

Electrical conductance — 3 units
siemensmillisiemensmicrosiemens

Capacitance — 5 units
picofaradnanofaradmicrofaradmillifaradfarad

Inductance — 3 units
microhenrymillihenryhenry

Electrical resistivity — 4 units
ohm meterohm centimetermicroohm centimeternanoohm meter

Electrical conductivity — 3 units
siemens per metermicrosiemens per centimetermillisiemens per centimeter

Magnetic flux density — 4 units
microteslamilliteslateslagauss

Magnetic flux — 3 units
microwebermilliweberweber

Magnetic moment — 4 units
joule per teslaBohr magnetonnuclear magnetonerg per gauss

Molar charge — 2 units
coulomb per moleampere-hour per mole

Chemistry

Amount of substance — 3 units
millimolemolekilomole

Molar mass — 2 units
gram per molekilogram per mole

Molar concentration — 3 units
mole per cubic metermillimole per litermole per liter (molar)

Molality — 2 units
millimole per kilogrammole per kilogram (molal)

Molal constant — 2 units
kelvin kilogram per moleCelsius kilogram per mole

Molar entropy — 3 units
joule per mole kelvinkilojoule per mole kelvincalorie per mole kelvin

Concentration — 5 units
percentfraction (0–1)parts per millionparts per billiongrain per US gallon (as CaCO₃)

Number density — 3 units
per cubic meterper cubic centimeterper cubic foot

Light, sound & radiation

Intensity — 5 units
microwatt per square metermilliwatt per square meterwatt per square meterkilowatt per square metermilliwatt per square centimeter

Sound level — 1 units
decibel

Optical power — 2 units
diopter (1/m)millidiopter

Radioactivity — 7 units
becquerelkilobecquerelmegabecquerelgigabecquerelmicrocuriemillicuriecurie

Wavenumber — 2 units
per meterper centimeter (kayser)

Fluids & other

Dynamic viscosity — 4 units
pascal secondmillipascal secondcentipoisepoise

Corrosion rate — 5 units
meter per yearmillimeter per yearmicrometer per yearmil per yearinch per year

Standard gravitational parameter — 2 units
cubic meter per second squaredcubic kilometer per second squared

Dimensionless — 2 units
ratiopercent

Count — 1 units
count

Other

Money — 1 units
currency unit

Cost per volume — 5 units
per cubic meterper literper US gallonper thousand US gallonsper thousand liters

Cost per mass — 4 units
per kilogramper gramper poundper tonne

Cost per energy — 5 units
per jouleper kilowatt-hourper gigajouleper thermper million BTU