Length Converter
Convert between metres, feet, inches, miles and eleven other units.
| Nanometrenm | 1,000,000,000 | |
| Millimetremm | 1,000 | |
| Centimetrecm | 100 | |
| Metrem | 1 | |
| Kilometrekm | 0.001 | |
| Inchin | 39.3701 | |
| Footft | 3.2808 | |
| Yardyd | 1.0936 | |
| Milemi | 0.0006 | |
| Nautical milenmi | 0.0005 | |
| Light yearly | 1.0570e-16 |
All conversions go through the metre using exact internationally agreed factors; only the display is rounded.
About Length Converter
Length is the unit family people convert most often, and the metric and imperial systems have coexisted long enough that mixing them is a daily reality in engineering and construction.
This converter shows your value in every supported unit at once, from nanometres to nautical miles, with exact conversion factors and adjustable precision.
How Length Converter works in your browser
Every unit is stored as an exact factor relative to the metre, using the international definitions — one inch is exactly 25.4 mm, one foot 0.3048 m and one nautical mile 1852 m. Your value is converted to metres once and then out to every other unit, so all results are consistent with each other.
Because the factors are exact, the only error is display rounding, which you can control with the precision setting.
When to use it
- Converting drawing or construction measurements between metric and imperial.
- Reading product dimensions listed in inches or feet.
- Translating distances in miles or nautical miles into kilometres.
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54. One inch is defined as 25.4 millimetres, so the conversion is exact rather than approximate.
How do I convert kilometres to miles?
Divide by 1.609344. A kilometre is about 0.621 miles, so 5 km is roughly 3.1 miles.
How exact are the conversions?
They use the internationally agreed definitions - one inch is exactly 25.4 millimetres - so the only error is display rounding.
What is a nautical mile?
Exactly 1852 metres, defined as one minute of latitude, and used in marine and air navigation.
Can I convert several units at once?
Yes. Enter one value and every supported unit updates simultaneously.