How to convert units

Pick what you want to convert: length, weight, temperature, volume, speed, data size, and more.
Type a number in the box for the unit you have. Every other unit of that type updates at once.
Read the unit you need. To go the other way, just type in that box instead. There is no convert button and no from/to menu.

Conversions use exact definitions, and results show up to 10 significant digits. You can type decimals with a dot or a comma, and numbers such as 1.5e6. Temperature and fuel economy are not simple multiplications, so they use the correct formulas (for example, °F = °C × 9/5 + 32).

Supported conversions

Every unit in a group converts to every other unit in that group, so there are hundreds of pairs. These are the most searched ones.

Length (13 units)

Centimetre to Inch (cm to in)
Inch to Centimetre (in to cm)
Metre to Foot (m to ft)
Foot to Metre (ft to m)
Kilometre to Mile (km to mi)
Mile to Kilometre (mi to km)
Millimetre to Inch (mm to in)
Inch to Millimetre (in to mm)
Foot to Inch (ft to in)
Yard to Metre (yd to m)
Metre to Yard (m to yd)
Nautical mile to Kilometre (nmi to km)
Metre to Inch (m to in)
Foot to Centimetre (ft to cm)
Centimetre to Foot (cm to ft)

Also: cm to inches, mm to inches, inches to cm, feet to meters, meters to feet, km to miles, miles to km, yards to meters, inches to mm.

Units: Nanometre, Micrometre, Millimetre, Centimetre, Metre, Kilometre, Mil (thou), Inch, Foot, Yard, Mile, Nautical mile, Light year.

Weight & mass (12 units)

Kilogram to Pound (kg to lb)
Pound to Kilogram (lb to kg)
Gram to Ounce (g to oz)
Ounce to Gram (oz to g)
Kilogram to Stone (kg to st)
Stone to Pound (st to lb)
Stone to Kilogram (st to kg)
Metric tonne to US short ton (t to ton)
Milligram to Gram (mg to g)
Troy ounce to Gram (oz t to g)
Pound to Ounce (lb to oz)
Gram to Pound (g to lb)

Also: kg to lbs, lbs to kg, pounds to kilograms, grams to ounces, ounces to grams, stone to kg, tonnes to tons.

Units: Microgram, Milligram, Gram, Kilogram, Metric tonne, Ounce, Pound, Stone, US short ton, UK long ton, Carat, Troy ounce.

Temperature (5 units)

Celsius to Fahrenheit (°C to °F)
Fahrenheit to Celsius (°F to °C)
Celsius to Kelvin (°C to K)
Kelvin to Celsius (K to °C)
Fahrenheit to Kelvin (°F to K)
Kelvin to Fahrenheit (K to °F)
Celsius to Rankine (°C to °R)

Also: Celsius to Fahrenheit, Fahrenheit to Celsius, Celsius to Kelvin, Kelvin to Celsius, °C to °F, °F to °C.

Units: Celsius, Fahrenheit, Kelvin, Rankine, Réaumur.

Area (10 units)

Square metre to Square foot (m² to ft²)
Square foot to Square metre (ft² to m²)
Acre to Hectare (ac to ha)
Hectare to Acre (ha to ac)
Square kilometre to Square mile (km² to mi²)
Square mile to Square kilometre (mi² to km²)
Square centimetre to Square inch (cm² to in²)
Square inch to Square centimetre (in² to cm²)
Square yard to Square metre (yd² to m²)
Acre to Square foot (ac to ft²)
Acre to Square metre (ac to m²)

Also: square feet to square meters, sq ft to m2, acres to hectares, hectares to acres, square miles to square km.

Units: Square millimetre, Square centimetre, Square metre, Hectare, Square kilometre, Square inch, Square foot, Square yard, Acre, Square mile.

Volume & cooking (20 units)

Litre to Gallon (US) (L to gal US)
Gallon (US) to Litre (gal US to L)
Millilitre to Fluid ounce (US) (mL to fl oz US)
Fluid ounce (US) to Millilitre (fl oz US to mL)
Cup (US) to Millilitre (cup US to mL)
Millilitre to Cup (US) (mL to cup US)
Tablespoon (US) to Teaspoon (US) (tbsp US to tsp US)
Tablespoon (US) to Millilitre (tbsp US to mL)
Teaspoon (US) to Millilitre (tsp US to mL)
Cup (US) to Tablespoon (US) (cup US to tbsp US)
Cup (US) to Fluid ounce (US) (cup US to fl oz US)
Pint (US) to Millilitre (pt US to mL)
Quart (US) to Litre (qt US to L)
Gallon (UK) to Gallon (US) (gal UK to gal US)
Cubic metre to Cubic foot (m³ to ft³)
Fluid ounce (US) to Fluid ounce (UK) (fl oz US to fl oz UK)

Also: liters to gallons, gallons to liters, ml to oz, cups to ml, tablespoons to teaspoons, cups to tablespoons, fluid ounces to ml, quarts to liters, pints to ml.

Units: Millilitre, Centilitre, Litre, Cubic metre, Teaspoon (metric, 5 mL), Tablespoon (metric, 15 mL), Cup (metric, 250 mL), Teaspoon (US), Tablespoon (US), Fluid ounce (US), Cup (US), Pint (US), Quart (US), Gallon (US), Fluid ounce (UK), Pint (UK), Quart (UK), Gallon (UK), Cubic inch, Cubic foot.

Speed (6 units)

Mile per hour to Kilometre per hour (mph to km/h)
Kilometre per hour to Mile per hour (km/h to mph)
Metre per second to Kilometre per hour (m/s to km/h)
Kilometre per hour to Metre per second (km/h to m/s)
Metre per second to Mile per hour (m/s to mph)
Mile per hour to Metre per second (mph to m/s)
Knot to Kilometre per hour (kn to km/h)
Knot to Mile per hour (kn to mph)
Foot per second to Mile per hour (ft/s to mph)

Also: mph to km/h, km/h to mph, kph to mph, m/s to km/h, knots to mph, knots to km/h.

Units: Metre per second, Kilometre per hour, Mile per hour, Knot, Foot per second, Speed of light.

Time (12 units)

Hour to Minute (h to min)
Minute to Second (min to s)
Day to Hour (d to h)
Week to Day (wk to d)
Year (average) to Day (yr to d)
Year (average) to Week (yr to wk)
Day to Minute (d to min)
Hour to Second (h to s)
Second to Millisecond (s to ms)
Month (average) to Day (mo to d)
Year (average) to Hour (yr to h)

Also: hours to minutes, minutes to seconds, days to hours, weeks to days, years to days, years to hours.

Units: Nanosecond, Microsecond, Millisecond, Second, Minute, Hour, Day, Week, Month (average), Year (average), Decade, Century.

Digital storage (15 units)

Megabyte (1000² bytes) to Gigabyte (1000³ bytes) (MB to GB)
Gigabyte (1000³ bytes) to Megabyte (1000² bytes) (GB to MB)
Kilobyte (1000 bytes) to Megabyte (1000² bytes) (KB to MB)
Megabyte (1000² bytes) to Kilobyte (1000 bytes) (MB to KB)
Gigabyte (1000³ bytes) to Terabyte (1000⁴ bytes) (GB to TB)
Terabyte (1000⁴ bytes) to Gigabyte (1000³ bytes) (TB to GB)
Byte to Bit (B to bit)
Megabyte (1000² bytes) to Megabit (MB to Mbit)
Megabit to Megabyte (1000² bytes) (Mbit to MB)
Gibibyte (1024³ bytes) to Gigabyte (1000³ bytes) (GiB to GB)
Gigabyte (1000³ bytes) to Gibibyte (1024³ bytes) (GB to GiB)
Mebibyte (1024² bytes) to Megabyte (1000² bytes) (MiB to MB)
Terabyte (1000⁴ bytes) to Tebibyte (1024⁴ bytes) (TB to TiB)
Kibibyte (1024 bytes) to Byte (KiB to B)
Gigabyte (1000³ bytes) to Kilobyte (1000 bytes) (GB to KB)

Also: MB to GB, GB to MB, KB to MB, GB to TB, TB to GB, bytes to bits, GiB to GB, megabits to megabytes.

Units: Bit, Byte, Kilobit, Megabit, Gigabit, Kilobyte (1000 bytes), Megabyte (1000² bytes), Gigabyte (1000³ bytes), Terabyte (1000⁴ bytes), Petabyte (1000⁵ bytes), Kibibyte (1024 bytes), Mebibyte (1024² bytes), Gibibyte (1024³ bytes), Tebibyte (1024⁴ bytes), Pebibyte (1024⁵ bytes).

Data transfer rate (12 units)

Megabit per second to Megabyte per second (Mbit/s to MB/s)
Megabyte per second to Megabit per second (MB/s to Mbit/s)
Gigabit per second to Megabyte per second (Gbit/s to MB/s)
Gigabit per second to Megabit per second (Gbit/s to Mbit/s)
Megabit per second to Kilobit per second (Mbit/s to kbit/s)
Kilobit per second to Megabit per second (kbit/s to Mbit/s)
Megabyte per second to Kilobyte per second (MB/s to KB/s)
Mebibyte per second to Megabit per second (MiB/s to Mbit/s)

Also: Mbps to MB/s, MB/s to Mbps, Gbps to MB/s, Mbps to Gbps, kbps to Mbps.

Units: Bit per second, Kilobit per second, Megabit per second, Gigabit per second, Terabit per second, Byte per second, Kilobyte per second, Megabyte per second, Gigabyte per second, Kibibyte per second, Mebibyte per second, Gibibyte per second.

Pressure (11 units)

Pound per square inch to Bar (psi to bar)
Bar to Pound per square inch (bar to psi)
Pound per square inch to Kilopascal (psi to kPa)
Kilopascal to Pound per square inch (kPa to psi)
Standard atmosphere to Pascal (atm to Pa)
Standard atmosphere to Pound per square inch (atm to psi)
Bar to Standard atmosphere (bar to atm)
Millimetre of mercury to Kilopascal (mmHg to kPa)
Inch of mercury to Hectopascal (inHg to hPa)
Bar to Kilopascal (bar to kPa)
Millibar to Hectopascal (mbar to hPa)

Also: psi to bar, bar to psi, psi to kPa, kPa to psi, atm to Pa, mmHg to kPa, inHg to hPa.

Units: Pascal, Hectopascal, Kilopascal, Megapascal, Bar, Millibar, Standard atmosphere, Pound per square inch, Torr, Millimetre of mercury, Inch of mercury.

Energy (10 units)

Kilocalorie (food Calorie) to Kilojoule (kcal to kJ)
Kilojoule to Kilocalorie (food Calorie) (kJ to kcal)
Calorie (thermochemical) to Joule (cal to J)
Joule to Calorie (thermochemical) (J to cal)
Kilowatt hour to Megajoule (kWh to MJ)
Kilowatt hour to British thermal unit (IT) (kWh to BTU)
British thermal unit (IT) to Kilojoule (BTU to kJ)
Watt hour to Joule (Wh to J)
Kilowatt hour to Kilocalorie (food Calorie) (kWh to kcal)
Electronvolt to Joule (eV to J)

Also: calories to joules, kcal to kJ, kWh to MJ, BTU to kJ, kWh to BTU, Wh to joules.

Units: Joule, Kilojoule, Megajoule, Calorie (thermochemical), Kilocalorie (food Calorie), Watt hour, Kilowatt hour, British thermal unit (IT), Foot-pound force, Electronvolt.

Power (9 units)

Kilowatt to Horsepower (mechanical) (kW to hp)
Horsepower (mechanical) to Kilowatt (hp to kW)
Horsepower (mechanical) to Watt (hp to W)
Watt to BTU per hour (W to BTU/h)
BTU per hour to Watt (BTU/h to W)
Kilowatt to Horsepower (metric) (kW to PS)
Horsepower (metric) to Horsepower (mechanical) (PS to hp)
Megawatt to Horsepower (mechanical) (MW to hp)
Watt to Milliwatt (W to mW)

Also: kW to hp, hp to kW, watts to BTU/h, horsepower to watts, kW to PS.

Units: Milliwatt, Watt, Kilowatt, Megawatt, Gigawatt, Horsepower (mechanical), Horsepower (metric), BTU per hour, Foot-pound per second.

Angle (7 units)

Degree to Radian (° to rad)
Radian to Degree (rad to °)
Degree to Gradian (° to grad)
Degree to Arcminute (° to ′)
Turn (revolution) to Degree (turn to °)
Arcsecond to Degree (″ to °)

Also: degrees to radians, radians to degrees, degrees to gradians, turns to degrees, arcseconds to degrees.

Units: Degree, Radian, Gradian, Arcminute, Arcsecond, Turn (revolution), Milliradian (NATO mil).

Frequency (7 units)

Megahertz to Gigahertz (MHz to GHz)
Gigahertz to Megahertz (GHz to MHz)
Hertz to Revolutions per minute (Hz to rpm)
Revolutions per minute to Hertz (rpm to Hz)
Kilohertz to Hertz (kHz to Hz)
Revolutions per minute to Radian per second (rpm to rad/s)
Gigahertz to Hertz (GHz to Hz)

Also: MHz to GHz, GHz to MHz, Hz to rpm, rpm to Hz, kHz to Hz.

Units: Hertz, Kilohertz, Megahertz, Gigahertz, Terahertz, Revolutions per minute, Radian per second.

Fuel economy (4 units)

Miles per gallon (US) to Litres per 100 km (mpg US to L/100 km)
Litres per 100 km to Miles per gallon (US) (L/100 km to mpg US)
Miles per gallon (US) to Kilometres per litre (mpg US to km/L)
Kilometres per litre to Miles per gallon (US) (km/L to mpg US)
Miles per gallon (UK) to Miles per gallon (US) (mpg UK to mpg US)
Miles per gallon (US) to Miles per gallon (UK) (mpg US to mpg UK)
Litres per 100 km to Kilometres per litre (L/100 km to km/L)
Miles per gallon (UK) to Litres per 100 km (mpg UK to L/100 km)

Also: mpg to L/100 km, L/100 km to mpg, mpg to km/L, UK mpg to US mpg, km/L to mpg.

Units: Litres per 100 km, Kilometres per litre, Miles per gallon (US), Miles per gallon (UK).

Questions

Is anything I type sent to a server?

No. The numbers are converted by your browser as you type. Nothing is uploaded, saved, or tracked.

How accurate are the conversions?

The tool uses the exact definitions, such as 1 inch = 2.54 cm, 1 pound = 0.45359237 kg, and 1 US gallon = 3.785411784 litres. Results are shown with up to 10 significant digits, so tiny rounding noise from computer arithmetic is hidden.

What is the difference between US and UK (imperial) gallons, pints, and fluid ounces?

They are different sizes. A US gallon is 3.785 litres and a UK gallon is 4.546 litres. A US fluid ounce is 29.57 mL and a UK one is 28.41 mL. Pick the volume unit marked US or UK to match your recipe or fuel receipt.

Why do KB, MB, and GB differ from KiB, MiB, and GiB?

KB, MB, and GB are powers of 1000 (1 MB = 1,000,000 bytes), as used by drive makers and networks. KiB, MiB, and GiB are powers of 1024 (1 MiB = 1,048,576 bytes), the way many operating systems count memory and files. That is why a "500 GB" drive shows less than 500 GiB.

How do I convert mpg to L/100 km?

Choose "Fuel economy", then type your mpg into the "Miles per gallon (US)" box, or the UK one if your gallons are imperial. The L/100 km box shows the result. The two scales run in opposite directions, so 30 mpg (US) is about 7.8 L/100 km, and a higher mpg means a lower L/100 km.

Credits

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