Convert miles to kilometres

Reading an American travel guide, a race entry or the odometer of an imported car means dealing with miles, which then need translating into the metric system.

The number of miles is multiplied by 1.609344. The result is exact because the international mile is defined by agreement in terms of the metre.

When you need this conversion

Reading an American spec sheet, making sense of the odometer on an imported car, planning a route from a British map, or understanding the range quoted for an electric vehicle in the US market. In all of these the figure arrives in miles and has to be translated.

Fuel consumption changes units too

Converting the distance is not enough. American consumption is given in miles per gallon, and the US gallon is 3.785 litres, different from the British imperial gallon of 4.546. Converting 30 US mpg to litres per hundred kilometres gives 7.84; using the imperial gallon it would come out at 9.42. It is a common mistake when comparing cars.

Electric vehicle range

Range figures are published under different test cycles: the American EPA usually gives more conservative values than the European WLTP. Converting EPA miles to kilometres does not make them comparable with a WLTP figure, even once the unit matches.

Distance running

Popular distances in English-speaking countries include the 5K and 10K, but also the mile, the five mile and the half marathon. A mile is 1,609 metres, a little over four laps of an athletics track.