How the conversion works
Every supported unit is defined as a fixed multiple of the metre. To convert, the calculator first turns your value into metres using the source unit's factor, then divides by the target unit's factor to express it in the unit you want.
Because all conversions pass through a single base unit, switching between metric and imperial lengths is exact and consistent in either direction.
Using the converter
Pick the unit you are starting from, the unit you want, and enter the value. The result updates to the target unit.
- Handy reference: 1 inch = 2.54 cm and 1 mile = 1.609 km.
- Swap the From and To selections to reverse a conversion.
Practical tips
For everyday estimates a rough conversion is often enough: a metre is a little over a yard, and a kilometre is about six tenths of a mile.
- Use millimetres or centimetres for small, precise measurements.
- Use kilometres or miles for travel distances.
Caveats and common mistakes
Make sure the From and To units are the ones you intend, since selecting them the wrong way round gives a result that looks plausible but is inverted. This tool converts length only, so it will not handle area or volume units.
Formula
result = value × factor[from] ÷ factor[to]