Unit Converter

Convert length, weight and temperature between metric and imperial units.

How to use

Choose a category: length, weight or temperature.
Enter a value and pick the unit to convert from.
Pick the unit to convert to — the result updates instantly.

How the Unit Converter works

A general-purpose converter covering length, weight, volume, temperature and more in one place, for when you do not want a dedicated page per pair.

Each unit is stored as an exact factor relative to its category's base unit. Converting means multiplying into the base and dividing out to the target. Temperature is handled separately because its scales need an offset as well as a ratio.

result = value × (factor of source ÷ factor of target)

Worked example

Converting 5 miles to kilometres: 5 × 1609.344 / 1000 = 8.04672 km, exactly.

Things worth knowing

The factors used are the exact standards-defined values, so metric-to-imperial conversions are exact rather than approximate.
For a specific pair with the formula, a reference table and full unit definitions, use the dedicated converter pages.

Frequently asked questions

Which units are supported?

Length (m, km, cm, mm, mi, yd, ft, in), weight (kg, g, lb, oz, t) and temperature (C, F, K).

How accurate is it?

Conversions use standard factors and are accurate for everyday use.

Are these conversions exact?

For length, mass, area and volume, yes — the inch has been exactly 25.4 mm and the pound exactly 0.45359237 kg since 1959.