Unit Converter

How it works

Six categories are covered: length, weight, temperature, area, volume, and speed. Each conversion goes through the category's base unit, so any pair of units within a category converts directly, from millimetres to miles or from teaspoons to gallons.

Temperature is handled as the affine conversion it is rather than a simple ratio, so Celsius, Fahrenheit, and Kelvin convert with their offsets applied and 0 °C correctly becomes 32 °F.

Results are shown to ten significant digits, with values below one millionth or above a trillion switched to exponential notation so that precision is neither lost nor faked.

Frequently asked questions

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 and add 32, so 20 °C is 68 °F. The reverse subtracts 32 first and then multiplies by 5/9. The offset is why temperature cannot be converted with a single factor.

Which gallon does the volume converter use?

The US liquid gallon of about 3.78541 litres, along with the US cup, pint, and quart. The imperial gallon of 4.54609 litres is a different unit and is not included.

Why does a conversion show a long decimal?

Because most conversions between systems are not exact in base ten. Values are given to ten significant digits so you can round where your own precision requires it.

Is a kilogram a unit of weight or mass?

Strictly of mass, and the pound is defined against it, at 0.45359237 kg exactly. In everyday use the two are converted as this tool does, which is correct as long as you stay on Earth.