Units and measurement
Unit Guide
Explore definitions, symbols, history and related conversion tools for measurement units.Length units
View conversions- mMeterThe meter is the base unit of length in the International System of Units. It is used to express distance and size across science, engineering and everyday life.
- kmKilometerThe kilometer is a unit of length equal to 1,000 meters. It is commonly used for roads, cities and geographical distances.
- cmCentimeterThe centimeter is a unit of length equal to one hundredth of a meter. It is widely used for everyday dimensions and small objects.
- mmMillimeterThe millimeter is a unit of length equal to one thousandth of a meter. It is widely used in technical and precision work.
- miMileThe mile is a non-metric unit of length commonly used in the United States and the United Kingdom. One international mile is exactly 1,609.344 meters.
- ftFootThe foot is a unit of length used in imperial and United States customary measurement systems. One international foot is exactly 0.3048 meters.
- inInchThe inch is a short unit of length used in imperial and United States customary systems. One inch is exactly 2.54 centimeters.
- ydYardThe yard is a unit of length used in imperial and United States customary systems. One yard is exactly 0.9144 meters.
- dmDecimeterDecimeter is a length unit used to express distance, size or travel range in practical measurement work.
- µmMicrometerMicrometer is a length unit used to express distance, size or travel range in practical measurement work.
- nmNanometerNanometer is a length unit used to express distance, size or travel range in practical measurement work.
- pmPicometerPicometer is a length unit used to express distance, size or travel range in practical measurement work.
- furFurlongFurlong is a length unit used to express distance, size or travel range in practical measurement work.
- nmiNautical mileNautical mile is a length unit used to express distance, size or travel range in practical measurement work.
- AUAstronomical UnitAstronomical Unit is a length unit used to express distance, size or travel range in practical measurement work.
- lyLight-yearLight-year is a length unit used to express distance, size or travel range in practical measurement work.
- pcParsecParsec is a length unit used to express distance, size or travel range in practical measurement work.
- ÅAngstromAngstrom is a length unit used to express distance, size or travel range in practical measurement work.
- ftmFathomFathom is a length unit used to express distance, size or travel range in practical measurement work.
- arshinArshinArshin is a length unit used to express distance, size or travel range in practical measurement work.
- endazeEndazeEndaze is a length unit used to express distance, size or travel range in practical measurement work.
- pusByzantine FootByzantine Foot is a length unit used to express distance, size or travel range in practical measurement work.
- orgyiaByzantine FathomByzantine Fathom is a length unit used to express distance, size or travel range in practical measurement work.
- cigCigCig is a length unit used to express distance, size or travel range in practical measurement work.
Mass units
View conversions- kgKilogramThe kilogram is the base unit of mass in the International System of Units. It is central to science, commerce and engineering.
- gGramThe gram is a unit of mass equal to one thousandth of a kilogram. It is widely used for food, laboratory materials and small quantities.
- mgMilligramThe milligram is a very small unit of mass equal to one thousandth of a gram. It is essential in medicine and laboratory work.
- lbPoundThe pound is a unit of mass used in imperial and United States customary systems. One international pound is exactly 0.45359237 kilograms.
- tTonneThe metric tonne is a large mass unit equal to 1,000 kilograms. It is widely used for heavy loads and industrial quantities.
- ozOunceThe ounce is a small mass unit used in imperial and United States customary systems. One avoirdupois ounce equals 28.349523125 grams.
- okkaOkkaThe okka is a traditional mass unit used in the Ottoman Empire, still known in Turkey and the region today.
- dirhemDirhamThe dirham is a small traditional Ottoman mass unit, equal to one four-hundredth of an okka.
- litraByzantine LitraThe litra is a traditional mass unit used in the Byzantine Empire.
- ounkiaByzantine OunceThe ounkia is a small Byzantine mass unit, one twelfth of a Byzantine litra.
- qQuintalQuintal is a unit used in mass conversions and practical measurement work.
- stStoneStone is a unit used in mass conversions and practical measurement work.
- grGrainGrain is a unit used in mass conversions and practical measurement work.
- DaDaltonDalton is a unit used in mass conversions and practical measurement work.
- miskalMiskalMiskal is a unit used in mass conversions and practical measurement work.
- batmanBatmanBatman is a unit used in mass conversions and practical measurement work.
- oztTroy OunceTroy Ounce is a unit used in mass conversions and practical measurement work.
- ctCaratCarat is a unit used in mass conversions and practical measurement work.
Volume units
View conversions- LLiterThe liter is a widely used volume unit for liquids and capacities. One liter equals 0.001 cubic meters.
- m³Cubic MeterThe cubic meter is the SI derived unit of volume. It is the standard reference for larger capacities and technical volumes.
- mLMilliliterThe milliliter is a small volume unit equal to one thousandth of a liter. It is common in precise liquid measurements.
- dLDeciliterDeciliter is a volume unit used for liquids, containers, storage and technical capacity calculations.
- cLCentiliterCentiliter is a volume unit used for liquids, containers, storage and technical capacity calculations.
- tbspMetric TablespoonMetric Tablespoon is a volume unit used for liquids, containers, storage and technical capacity calculations.
- tspMetric TeaspoonMetric Teaspoon is a volume unit used for liquids, containers, storage and technical capacity calculations.
- glassTurkish Water GlassTurkish Water Glass is a volume unit used for liquids, containers, storage and technical capacity calculations.
- cm³Cubic CentimeterCubic Centimeter is a volume unit used for liquids, containers, storage and technical capacity calculations.
- ft³Cubic FootCubic Foot is a volume unit used for liquids, containers, storage and technical capacity calculations.
- in³Cubic InchCubic Inch is a volume unit used for liquids, containers, storage and technical capacity calculations.
- galUS Liquid GallonUS Liquid Gallon is a volume unit used for liquids, containers, storage and technical capacity calculations.
- qtUS QuartUS Quart is a volume unit used for liquids, containers, storage and technical capacity calculations.
- imp qtImperial QuartImperial Quart is a volume unit used for liquids, containers, storage and technical capacity calculations.
- fl ozUS Fluid OunceUS Fluid Ounce is a volume unit used for liquids, containers, storage and technical capacity calculations.
- imp fl ozImperial Fluid OunceImperial Fluid Ounce is a volume unit used for liquids, containers, storage and technical capacity calculations.
- ptUS PintUS Pint is a volume unit used for liquids, containers, storage and technical capacity calculations.
- imp ptImperial PintImperial Pint is a volume unit used for liquids, containers, storage and technical capacity calculations.
- pkUS PeckUS Peck is a volume unit used for liquids, containers, storage and technical capacity calculations.
- buUS BushelUS Bushel is a volume unit used for liquids, containers, storage and technical capacity calculations.
- imp galImperial GallonImperial Gallon is a volume unit used for liquids, containers, storage and technical capacity calculations.
- bblBarrelBarrel is a volume unit used for liquids, containers, storage and technical capacity calculations.
- kileKileKile is a volume unit used for liquids, containers, storage and technical capacity calculations.
- shinikShinikShinik is a volume unit used for liquids, containers, storage and technical capacity calculations.
Area units
View conversions- m²Square MeterThe square meter is the SI derived unit of area. It is the standard reference for surfaces, floor area and section sizing.
- haHectareThe hectare is a large area unit widely used for land measurement. One hectare is exactly 10,000 square meters.
- ft²Square FootThe square foot is an area unit used in imperial and US customary systems. One square foot is about 0.092903 square meters.
- cm²Square CentimeterSquare Centimeter is an area unit used to describe surface size, land coverage or geometric sections.
- mm²Square MillimeterSquare Millimeter is an area unit used to describe surface size, land coverage or geometric sections.
- km²Square KilometerSquare Kilometer is an area unit used to describe surface size, land coverage or geometric sections.
- aAreAre is an area unit used to describe surface size, land coverage or geometric sections.
- in²Square InchSquare Inch is an area unit used to describe surface size, land coverage or geometric sections.
- yd²Square YardSquare Yard is an area unit used to describe surface size, land coverage or geometric sections.
- acAcreAcre is an area unit used to describe surface size, land coverage or geometric sections.
- donumDonumDonum is an area unit used to describe surface size, land coverage or geometric sections.
- feddanFeddanFeddan is an area unit used to describe surface size, land coverage or geometric sections.
- qiratQirat (Land)Qirat (Land) is an area unit used to describe surface size, land coverage or geometric sections.
- sehmSahm (Land Share)Sahm (Land Share) is an area unit used to describe surface size, land coverage or geometric sections.
- dekarDecareDecare is an area unit used to describe surface size, land coverage or geometric sections.
- decimalDecimal (Land)Decimal (Land) is an area unit used to describe surface size, land coverage or geometric sections.
- killaKillaKilla is an area unit used to describe surface size, land coverage or geometric sections.
- kanalKanalKanal is an area unit used to describe surface size, land coverage or geometric sections.
- marlaMarlaMarla is an area unit used to describe surface size, land coverage or geometric sections.
- gunthaGunthaGuntha is an area unit used to describe surface size, land coverage or geometric sections.
- centCent (Land)Cent (Land) is an area unit used to describe surface size, land coverage or geometric sections.
- groundGroundGround is an area unit used to describe surface size, land coverage or geometric sections.
- biswaBiswaBiswa is an area unit used to describe surface size, land coverage or geometric sections.
- kathaKathaKatha is an area unit used to describe surface size, land coverage or geometric sections.
- bighaBighaBigha is an area unit used to describe surface size, land coverage or geometric sections.
- tsuboTsuboTsubo is an area unit used to describe surface size, land coverage or geometric sections.
Pressure units
View conversions- PaPascalThe pascal is the SI derived unit of pressure. It is defined by the relationship 1 Pa = 1 N/m².
- kPaKilopascalThe kilopascal is a pressure unit equal to 1,000 pascals. It provides more readable numbers for practical engineering work.
- barBarThe bar is a pressure unit equal to 100,000 pascals. It is widely used in industrial and service equipment.
- psiPSIPSI stands for pound-force per square inch. It is a common pressure unit in Anglo-American technical practice.
- mmHgMillimeter of MercuryThe millimeter of mercury is a pressure unit based on the height of a mercury column. It remains historically important in medicine and laboratory practice.
- kgf/cm²Kilogram-Force per Square CentimeterKilogram-force per square centimeter is a non-SI pressure unit derived from force distributed over area. It still appears on older gauges and service documents.
- MPaMegapascalMegapascal is a pressure unit used to express mechanical, atmospheric or process pressure values.
- hPaHectopascalHectopascal is a pressure unit used to express mechanical, atmospheric or process pressure values.
- mbarMillibarMillibar is a pressure unit used to express mechanical, atmospheric or process pressure values.
- atmAtmosphereAtmosphere is a pressure unit used to express mechanical, atmospheric or process pressure values.
- atTechnical AtmosphereTechnical Atmosphere is a pressure unit used to express mechanical, atmospheric or process pressure values.
- mmH2OMillimeter of WaterMillimeter of Water is a pressure unit used to express mechanical, atmospheric or process pressure values.
- TorrTorrTorr is a pressure unit used to express mechanical, atmospheric or process pressure values.
Temperature units
View conversions- °CCelsiusCelsius is one of the most widely used temperature scales in daily and engineering practice.
- °FFahrenheitFahrenheit is a temperature scale still widely used in the United States.
- KKelvinKelvin is the SI base unit of thermodynamic temperature.
- °RRankineRankine is a unit used in temperature conversions and practical measurement work.
- °RéRéaumurRéaumur is a unit used in temperature conversions and practical measurement work.
Speed units
View conversions- m/sMeter per SecondThe meter per second is the SI derived unit of speed. It is the main reference for science and engineering.
- km/hKilometer per HourKilometer per hour is a practical speed unit widely used in road transport.
- mphMile per HourMiles per hour is a speed unit still common in the United States and other imperial-road contexts.
- cSpeed of LightThe speed of light is a fundamental physical constant representing how fast light and electromagnetic waves propagate in a vacuum.
- knKnotThe knot is a unit of speed used in marine and air navigation, equal to one nautical mile per hour.
- km/sKilometer per SecondKilometer per Second is a unit used in speed conversions and practical measurement work.
- ft/sFoot per SecondFoot per Second is a unit used in speed conversions and practical measurement work.
- m/minMeter per MinuteMeter per Minute is a unit used in speed conversions and practical measurement work.
- km/minKilometer per MinuteKilometer per Minute is a unit used in speed conversions and practical measurement work.
- cm/sCentimeter per SecondCentimeter per Second is a unit used in speed conversions and practical measurement work.
Energy units
View conversions- JJouleThe joule is the SI derived unit of energy. It is used for work, heat and energy quantities.
- kWhKilowatt-hourThe kilowatt-hour is a widely used practical energy unit for electrical consumption.
- kJKilojouleThe kilojoule is equal to 1,000 joules, used to express larger energy values practically.
- calCalorieThe calorie is a traditional energy unit originally defined based on heating water.
- kcalKilocalorieThe kilocalorie (food Calorie) is the unit actually used on food nutrition labels.
- BtuBritish Thermal UnitThe British Thermal Unit is a traditional energy unit used in US heating and cooling systems.
- WhWatt-hourThe watt-hour is a practical energy unit representing the energy consumed at a rate of one watt for one hour.
- MJMegajouleMegajoule is a unit used in energy and power conversions and practical measurement work.
- thThermTherm is a unit used in energy and power conversions and practical measurement work.
- quad BTUQuad BTUQuad BTU is a unit used in energy and power conversions and practical measurement work.
- eVElectronvoltElectronvolt is a unit used in energy and power conversions and practical measurement work.
Power units
View conversions- WWattThe watt is the SI derived unit of power. It expresses the rate of energy transfer.
- kWKilowattThe kilowatt is a power unit equal to 1,000 watts. It is widely used for equipment and system capacity.
- hpMetric Horsepower (PS)Metric horsepower (PS, CV) is a traditional unit of power used for engine output in Europe and much of the world; it equals 735.49875 watts. The mechanical horsepower (hp) used in the US and UK is slightly larger, 745.7 watts.
- MWMegawattThe megawatt (MW) is a large-scale power unit equal to 1,000,000 watts, used to express the capacity of power plants and large facilities.
- HPHorsepower (Mechanical)Mechanical horsepower (HP) is the traditional Imperial/US power unit, equal to 745.7 watts — distinct from the metric horsepower (PS/CV).
- TRTon of RefrigerationTon of Refrigeration is a unit used in power conversions and practical measurement work.
- BTU/hBTU per hourBTU per hour is a unit used in power conversions and practical measurement work.
Data storage units
View conversions- bitBitBit is a digital storage unit used to express file size, memory or device capacity.
- BByteByte is a digital storage unit used to express file size, memory or device capacity.
- KibitKibibitKibibit is a digital storage unit used to express file size, memory or device capacity.
- MibitMebibitMebibit is a digital storage unit used to express file size, memory or device capacity.
- GibitGibibitGibibit is a digital storage unit used to express file size, memory or device capacity.
- TibitTebibitTebibit is a digital storage unit used to express file size, memory or device capacity.
- kbitKilobitKilobit is a digital storage unit used to express file size, memory or device capacity.
- MbitMegabitMegabit is a digital storage unit used to express file size, memory or device capacity.
- GbitGigabitGigabit is a digital storage unit used to express file size, memory or device capacity.
- TbitTerabitTerabit is a digital storage unit used to express file size, memory or device capacity.
- KBKilobyteKilobyte is a digital storage unit used to express file size, memory or device capacity.
- MBMegabyteMegabyte is a digital storage unit used to express file size, memory or device capacity.
- GBGigabyteGigabyte is a digital storage unit used to express file size, memory or device capacity.
- TBTerabyteTerabyte is a digital storage unit used to express file size, memory or device capacity.
- PBPetabytePetabyte is a digital storage unit used to express file size, memory or device capacity.
- KiBKibibyteKibibyte is a digital storage unit used to express file size, memory or device capacity.
- MiBMebibyteMebibyte is a digital storage unit used to express file size, memory or device capacity.
- GiBGibibyteGibibyte is a digital storage unit used to express file size, memory or device capacity.
- TiBTebibyteTebibyte is a digital storage unit used to express file size, memory or device capacity.
Time units
View conversions- sSecondThe second is the SI base unit of time. It underpins duration, speed and rate calculations.
- minMinuteThe minute is a practical time unit equal to 60 seconds.
- hHourThe hour is a widely used time unit equal to 3,600 seconds.
- dayDayThe day equals 24 hours and is based on Earth's rotation cycle.
- msMillisecondMillisecond is a unit used in time conversions and practical measurement work.
Electrical units
View conversions- VVoltThe volt is the SI derived unit of electric potential difference.
- kVKilovoltThe kilovolt is a voltage unit equal to 1,000 volts. It is common in medium- and high-voltage systems.
- AAmpereThe ampere is the SI base unit of electric current.
- mAMilliampereThe milliampere is a small current unit equal to one thousandth of an ampere.
- mVMillivoltThe millivolt is a small voltage unit equal to one thousandth of a volt, used for low-level electrical signals.
- kAKiloampereThe kiloampere is a large current unit equal to 1,000 amperes, used for short-circuit and lightning current levels.
Density units
View conversions- kg/m³Kilogram per Cubic MeterKilogram per cubic meter is the SI derived unit of density, expressing the mass of a substance contained in one cubic meter of volume.
- g/cm³Gram per Cubic CentimeterGram per cubic centimeter is a density unit widely used in laboratory and chemistry settings for small samples.
Force units
View conversions- NNewtonThe newton is the SI derived unit of force, defined as the force required to accelerate a 1-kilogram mass at 1 meter per second squared.
- kgfKilogram-ForceKilogram-force is a traditional, non-SI unit of force equal to the force exerted by gravity on a 1-kilogram mass at standard gravitational acceleration.
Torque units
View conversions- N·mNewton-MeterThe newton-meter is the SI derived unit of torque, equal to the rotational effect of a 1-newton force applied at a 1-meter lever arm.
- lb·ftPound-FootPound-foot is a traditional unit of torque used in British and American measurement systems, common in US-sourced automotive documents.
- kgf·mKilogram-Force MeterKilogram-force meter is a traditional torque unit found in older engine documentation.
Momentum units
View conversionsAngle units
View conversions- radRadianThe radian is the SI unit of angle, defined as the angle subtended at the center of a circle by an arc equal in length to the radius.
- °DegreeThe degree is the most common practical angle unit, dividing a full circle into 360 equal parts.
- gonGradianThe gradian divides a full circle into 400 equal parts, aligned with the decimal measurement system.
- turnFull TurnA full turn represents one complete rotation around a point, i.e. a full 360 degrees.
Frequency units
View conversions- HzHertzThe hertz is the SI unit of frequency, expressing how many times an event repeats per second.
- kHzKilohertzThe kilohertz is one thousand hertz, used to express mid-range audio and radio signal frequencies.
- MHzMegahertzThe megahertz is one million hertz, used to express FM radio, Wi-Fi and older computer processor speeds.
- GHzGigahertzThe gigahertz is one billion hertz, expressing modern computer processor speeds and high-frequency wireless communication.
Flow-rate units
View conversionsCapacitance units
View conversions- FFaradFarad is a capacitance unit used in electronic circuits, filters and energy-storage components.
- mFMillifaradMillifarad is a capacitance unit used in electronic circuits, filters and energy-storage components.
- µFMicrofaradMicrofarad is a capacitance unit used in electronic circuits, filters and energy-storage components.
- nFNanofaradNanofarad is a capacitance unit used in electronic circuits, filters and energy-storage components.
- pFPicofaradPicofarad is a capacitance unit used in electronic circuits, filters and energy-storage components.
Inductance units
View conversions- HHenryHenry is an inductance unit used in coils, filters, transformers and magnetic circuit calculations.
- mHMillihenryMillihenry is an inductance unit used in coils, filters, transformers and magnetic circuit calculations.
- µHMicrohenryMicrohenry is an inductance unit used in coils, filters, transformers and magnetic circuit calculations.