Kilometres to Miles

How to use KM to Miles Converter

1. 1
   Enter the kilometres. Decimals are fine — a marathon is 42.195.
2. 2
   Read the miles. To three decimals, with metres underneath.

About converting kilometres to miles

The statute mile of 1,609.344 metres is a survival of Roman measurement, from mille passus — a thousand paces of five feet each. It reached its present exact value through the same 1959 agreement that fixed the inch, which is why this conversion is a definition rather than an approximation. The awkward factor is why runners and drivers develop their own shortcuts, and why race distances sound arbitrary in whichever unit was not used to set them: a 5K is 3.107 miles, a 10K is 6.214, and the marathon is 26.219. The reverse is equally lopsided — a mile race is 1.609 kilometres, which is why the metric world runs 1500 metres instead. Where conversion misleads is speed limits and road distances, because those are set as round numbers in the local unit and converting them produces figures that look oddly specific. A 70 mph motorway limit is 112.65 km/h, and nobody signs it that way. The nautical mile is a different unit entirely, defined as one minute of arc along a meridian and standardised at 1,852 metres, which is why aviation and marine speeds in knots need their own conversion and not this one.

Frequently asked questions