Length Converter
Convert between metres, kilometres, miles, feet, inches and the rest, with exact factors.
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1 km
0.6213712 mi
Mile
In every unit
| Unit | Symbol | Value |
|---|---|---|
| Metre | m | 1,000 |
| Kilometre | km | 1 |
| Centimetre | cm | 100,000 |
| Millimetre | mm | 1,000,000 |
| Micrometre | µm | 1,000,000,000 |
| Nanometre | nm | 1,000,000,000,000 |
| Mile | mi | 0.6213712 |
| Yard | yd | 1,093.613 |
| Foot | ft | 3,280.84 |
| Inch | in | 39,370.08 |
| Nautical mile | nmi | 0.5399568 |
Metric and imperial lengths, converted with the internationally agreed definitions rather than the approximations people remember. An inch is exactly 2.54 centimetres, and everything imperial follows from that.
How it works
Each unit is defined as a number of metres, so a conversion is one multiplication into metres and one division out of them. The table below the result shows the same length in every unit at once, which is usually faster than converting twice.
Since 1959 the yard has been defined as exactly 0.9144 metres, which fixes the foot at 0.3048 and the inch at 0.0254. The mile is 1609.344 metres exactly. None of these are rounded here.
Examples
| Case | Input | Result |
|---|---|---|
| A road distance | 100 km | 62.137 miles |
| A height | 6 ft | 1.8288 m |
| A screen | 27 in | 68.58 cm |
Frequently asked questions
Is a nautical mile the same as a mile?
No. A nautical mile is 1852 metres exactly, roughly one minute of latitude, and is used at sea and in the air. A statute mile is 1609.344 metres. Mixing them up is a fifteen per cent error.
Why is 5 km not exactly 3.1 miles?
Because the two systems are not related by a round number. 5 km is 3.106855… miles; the familiar figures are rounded, and rounding twice in a row is how small errors become large ones.
Good to know
- Every factor used here is an exact definition rather than a rounded measurement, so the only error in a result is the one that comes from displaying it with a finite number of digits.