Length Unit Converter

Convert lengths and distances between millimetres, centimetres, metres, kilometres, inches, feet, yards and miles. Enter a measurement, choose the source and target units, and calculate the result. You can also compare the equivalent measurement in all eight units.

Convert a length

Length value

Enter a positive or negative numeric value, or zero. Negative values are accepted for mathematical use.

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Supported length units

This converter uses exact international definitions for the listed units, including the international foot, yard and mile.

Millimetre (mm) 1 mm = 0.001 m

Centimetre (cm) 1 cm = 0.01 m

Metre (m) Base unit of length

Kilometre (km) 1 km = 1,000 m

Inch (in) 1 in = 0.0254 m

Foot (ft) 1 ft = 0.3048 m

Yard (yd) 1 yd = 0.9144 m

Mile (mi) 1 mi = 1,609.344 m

How length conversion works

Each unit has a fixed conversion factor relative to the metre. The calculator first converts the entered measurement to metres, then converts that value into the target unit.

Result = input value × source-unit factor ÷ target-unit factor

For example, to convert 5 feet into metres:

5 × 0.3048 = 1.524 metres

To convert 2 kilometres into miles, the calculation is:

2 × 1,000 ÷ 1,609.344 ≈ 1.242742 miles

Results are displayed to a maximum of 10 decimal places, with trailing zeros removed. Very small or very large values may need scientific notation for additional precision; this calculator is intended for ordinary measurement conversions.

Frequently asked questions

How many millimetres are in one metre?

One metre equals 1,000 millimetres.

How many centimetres are in one inch?

One inch equals exactly 2.54 centimetres.

How many feet are in one metre?

One metre is approximately 3.28084 feet.

How many kilometres are in one mile?

One international mile equals exactly 1.609344 kilometres.

Can I convert in both directions?

Yes. Select any supported source unit and any target unit. Use the Swap units button to reverse the selected units.

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