Length converter
Decimals: 12.5 or 12,5, without thousands separators.
How length conversion works
Enter a number and choose its current unit and the unit you want. The converter uses exact international definitions, converts through metres and rounds only the displayed result. Swap exchanges the two units while keeping your entered number.
Convert through metres
Every supported unit has a fixed factor in metres. Multiply by the source factor, then divide by the target factor. Metric prefixes are exact powers of ten.
Converted value = Value × Source factor ÷ Target factor
- Choose the unit of the entered number.
- Choose the destination unit.
- Read or copy the displayed conversion.
2.5 metres equals 250 centimetres because 2.5 × 1 ÷ 0.01 = 250.
International feet, inches and miles
An inch is exactly 0.0254 metres. An international foot is exactly 0.3048 metres, and a yard is exactly 0.9144 metres. The ordinary mile and nautical mile are different units.
1 mile = 1609.344 m; 1 nautical mile = 1852 m
- Use Foot for the international foot, not the historical U.S. survey foot.
- Choose Mile for the ordinary land mile.
- Choose Nautical mile for navigation distances.
6 feet equals 1.8288 metres. One mile equals 1.609344 kilometres.
Precision and signed values
Set the maximum decimal places under Options. The ≈ symbol means the displayed number is rounded; the underlying factors remain exact. Very small results can round to zero at low precision.
1 nanometre = 0.000000000001 kilometres
- Increase precision to see very small conversions.
- Use decimals, not fractions such as 1/2; enter 0.5 instead.
- Negative numbers are accepted for signed measurements or displacements.
At six decimal places, 1 nm in km displays approximately zero. At twelve places, it displays 0.000000000001. Copy uses the displayed precision.
Definitions: NIST international unit factors · NIST SI