Kilometers (km) and Miles (mi) explained
The kilometer is the road-distance unit almost everywhere: Brazil, Mexico, continental Europe, most of Asia and Africa. It is a thousand meters, and it inherits the meter's definition from the speed of light. The mile is what you need when your audience is American or British — race listings, road signs, car specifications, fitness apps set to imperial units. The two systems collide most often for travellers and runners, and the collision is worse than it looks because the conversion factor is close to two thirds: an unconverted number is wrong by a third, which is enough to badly misjudge a driving day or a training run.
Formula and worked examples
mi = km ÷ 1.609344Divide kilometers by 1.609344, or multiply by 0.621371. A 10 km race is 6.21 miles. A 100 km/h motorway limit is 62.14 mph. The 42.195 km marathon is 26.219 miles. A 5 km parkrun is 3.11 miles, which is why it is sometimes advertised in the US as a "3.1-mile" event.
Kilometers (km) to Miles (mi) conversion table
Common Kilometers (km) values converted to Miles (mi). Every figure uses the same conversion factor as the calculator above.
| Kilometers (km) | Miles (mi) |
|---|---|
| 1 | 0.62137119 |
| 2 | 1.2427424 |
| 5 | 3.106856 |
| 10 | 6.2137119 |
| 20 | 12.427424 |
| 50 | 31.06856 |
| 100 | 62.137119 |
Where you will use this
Renting a car abroad and reporting mileage
A rental returned in Europe or Latin America shows kilometers on the odometer, but expense policies and insurance forms from a US employer ask for miles. A 1,200 km trip is 745.6 miles.
Translating race results for a US audience
Metric race distances need converting when you post results to a US running community. A 21.0975 km half marathon is 13.11 miles, and pace per kilometer needs converting separately to pace per mile.
Reading foreign vehicle specifications
European and Japanese manufacturers publish range and service intervals in kilometers. A 15,000 km service interval is 9,320 miles, which matters when you are comparing maintenance costs against a US-market equivalent.