A length converter converts a measurement from one unit of length to another. This converter supports metric units (mm, cm, m, km), imperial units (inches, feet, yards, miles) and nautical miles. All conversions use internationally recognised reference values.

1. Enter the value to convert.
2. Select the unit you are converting from.
3. Select the unit you are converting to.
4. Click Convert.

5 miles to kilometres: 5 × 1609.344 ÷ 1000 = 8.047 km
100 cm to inches: 100 × 0.01 ÷ 0.0254 = 39.37 in

The metric system is based on powers of 10, making conversions within the system straightforward. Imperial conversions use fixed ratios defined by international agreement. Nautical miles are used in maritime and aviation navigation and are based on one minute of arc of latitude.

• Confusing feet and foot — they are the same unit.
• Confusing statute miles with nautical miles — 1 nautical mile ≈ 1.852 km vs 1 statute mile ≈ 1.609 km.

How many centimetres are in an inch?

1 inch = 2.54 centimetres exactly (by international definition).

What is a nautical mile?

A nautical mile is 1,852 metres exactly. It is defined as one minute of arc of latitude along any meridian and is used in maritime and aviation navigation.