What is a length converter?
A length converter changes a measurement from one unit of distance to another. It is useful when a product specification, map, school task, construction plan or fitness tracker uses a unit you do not normally work with. Enter a value, choose the starting unit and choose the unit you need to see the converted result immediately.
This tool covers common metric and imperial length units: millimetres, centimetres, metres, kilometres, inches, feet, yards and miles. It runs in your browser, so the number you enter is processed locally and is never uploaded or saved.
How to use this length converter
- Type the measurement you want to convert into the value field.
- Choose its current unit in the From menu.
- Choose the target unit in the To menu.
- Read the converted value and the equivalent statement below the fields.
- Use Swap units to reverse the direction without selecting both units again.
For example, enter 5, choose kilometres as the starting unit and miles as the target unit to find the equivalent distance in miles. You can use decimals for precise measurements, such as 2.54 centimetres or 0.5 inches.
How length conversions work
Every unit in the converter has a fixed relationship to the metre, the base metric unit of length. The calculator first converts the entered measurement to metres, then converts those metres to the unit you selected as the result. This two-step method allows any supported pair of units to be converted accurately.
Some useful reference values are easy to remember: 10 millimetres make 1 centimetre, 100 centimetres make 1 metre and 1,000 metres make 1 kilometre. In imperial measurements, 12 inches make 1 foot, 3 feet make 1 yard and 1,760 yards make 1 mile. The exact international conversion is 1 inch = 2.54 centimetres, which means 1 foot = 30.48 centimetres.
Why use an online length converter?
Manual conversion is possible, but the required multiplication or division can be inconvenient when measurements include decimals or when moving between metric and imperial systems. A converter removes that arithmetic while retaining useful precision. It is especially handy when comparing furniture dimensions, planning travel distances, following a recipe or craft guide, checking an engineering drawing, or translating a running distance.
For formal work, use the same level of rounding requested by the task. This tool displays a clear, usable result, but a final measurement should be rounded to match the precision of the original figure and the purpose of the calculation.