Quick start
- Type a value.
- Choose the unit it is in, such as kilometres or pounds.
- Read the table of every matching unit.
What you can convert
Length, mass, area, volume, speed, time, digital storage, angle, energy, pressure and temperature, in both metric and imperial or US units.
Exact factors
Some conversions are fixed by definition and are exact: 1 inch = 2.54 cm, 1 foot = 0.3048 m, 1 mile = 1.609344 km and 1 pound = 0.45359237 kg. So a 5 km run is about 3.107 miles, and 70 kg is about 154.3 pounds.
Temperature needs a formula
Celsius, Fahrenheit and Kelvin start from different zero points, so you cannot just multiply. °F = °C × 9/5 + 32 and K = °C + 273.15. A normal body temperature of 37 °C is 98.6 °F.
Watch out for look-alike units
- A US gallon is 3.785 litres; a UK gallon is 4.546 litres.
- A US ton is 2,000 pounds; a metric tonne is 1,000 kg, about 2,205 pounds.
- A GB is 1,000,000,000 bytes, while a GiB is 1,073,741,824 bytes.
Common questions
How many feet are in a metre?
About 3.2808.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9. 100 °F ≈ 37.8 °C.
How many litres are in a cubic foot?
About 28.317.