Length Converter

Convert length and distance between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles and nautical miles — instantly, in both directions.

Centimetres (cm)Inches (in)
10.3937
20.7874
51.9685
103.937
207.874
5019.685
10039.3701

How length conversion works

Every unit here is defined in terms of the metre, so any conversion is two exact steps: convert the input to metres, then to the target unit. The key definitions are exact by international agreement:

Handy approximations

Frequently asked questions

How many centimetres are in an inch?
Exactly 2.54 cm — the inch has been defined this way internationally since 1959. So cm → inches is ÷ 2.54, and inches → cm is × 2.54.
How do I convert kilometres to miles?
1 mile = 1.609344 km, so divide kilometres by 1.609 (or multiply by 0.6214). 10 km ≈ 6.21 miles; a marathon’s 42.195 km ≈ 26.22 miles.
How many feet are in a metre?
1 metre ≈ 3.28084 feet (exactly 1 ÷ 0.3048). So 100 m ≈ 328 ft, and a 30 m building is roughly 98 ft tall.
What is a nautical mile?
A nautical mile is exactly 1,852 metres — about 1.15 land miles. It approximates one minute of latitude, which is why aviation and shipping use it.

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