Length Unit Converter — Free Online Tool

📏 Length Unit Converter

Metric and imperial length units don't line up neatly, which makes mental conversion between, say, feet and metres, or miles and kilometres, error-prone without a calculator on hand. This converter handles the common length units — millimetres, centimetres, metres, kilometres, inches, feet, yards and miles — converting any one of them to any other instantly as you type.

It's useful for everything from converting a recipe or DIY measurement, to checking a product's dimensions listed in a foreign unit, to quick unit sanity-checks while studying or working.

How to use the Length Unit Converter

Enter a value and choose its unit (the 'from' unit).
Choose the unit you want to convert to (the 'to' unit).
View the converted value instantly — or switch the two units with one click.

How the conversion works

Every supported unit is first converted to a common base unit (metres), then converted from metres into the target unit. For example, 1 inch = 0.0254 metres, 1 mile = 1609.344 metres, and 1 foot = 0.3048 metres — chaining through metres keeps the converter accurate for any combination of units without needing a separate formula for every possible pair.

Frequently asked questions

How many centimetres are in an inch?

1 inch is exactly 2.54 centimetres. This is the internationally agreed definition of the inch, and this converter uses that exact figure rather than a rounded approximation.

Is this converter precise enough for engineering or construction use?

The converter uses standard, internationally defined conversion factors and displays results to several decimal places, which is accurate for most everyday, DIY and academic purposes. For safety-critical engineering work, always cross-check against your project's specified standards and tolerances.

Can I convert between metric units only, like mm to km?

Yes — you can select any two units from the full list, including two metric units or two imperial units, not just metric-to-imperial conversions.