Unit Converters

Each converter shows the whole family of units at once. Enter a length in inches and you get millimetres, centimetres, metres, feet, yards, miles and nautical miles together, because the conversion you want next is usually in the same family as the one you just did. The factors are the exact defined ones, not rounded approximations: an inch is 25.4 millimetres by definition, and that is the value used.

The common ones

The length converter, weight converter, temperature converter and volume converter cover most of what people look for. Temperature is the one that behaves differently: it has an offset as well as a scale, so you cannot convert a temperature difference the same way you convert a temperature, and the page says so.

Measurement and engineering

For area, speed, pressure, energy, power, density and frequency there is a page each, with the units actually used in each field rather than every unit that has ever existed.

Everyday conversions

The cooking measurement converter handles cups, spoons, millilitres and grams, and is explicit that a cup of flour and a cup of sugar do not weigh the same, so it converts by ingredient where weight is involved. The data storage converter shows both the decimal and binary interpretations, which is why a 1 TB drive shows up as about 931 GB. The fuel economy converter moves between miles per gallon, litres per 100 km and kilometres per litre, including the difference between the US and imperial gallon.

If you would rather have one page for everything, the general unit converter covers several categories in a single interface.