Miles to Kilometers Converter

Converting miles to kilometres uses the factor 1.609344, which is exact by definition: the international mile is 5,280 feet, each foot exactly 0.3048 metres, giving 1,609.344 metres precisely. Multiply miles by 1.609344 for kilometres, or use the common shorthand of multiplying by 1.6, which is accurate to better than six parts in a thousand and perfectly adequate for road signs and casual estimates.

Running is where this conversion appears most often for most people, because race distances are standardised in metric while training in the United States and United Kingdom is frequently logged in miles. The standard distances convert to memorable figures: a 5K is 3.107 miles, a 10K is 6.214 miles, a half marathon at 21.0975 km is 13.109 miles, and the marathon's 42.195 km is 26.219 miles. That marathon distance has an odd origin — it was set at the 1908 London Olympics, reportedly extended so the race could finish in front of the royal box, and formally standardised in 1921.

Driving is the other common context. Speed limits, odometers, and road signs differ between the US and UK on one side and most of the world on the other, so distance conversions matter for trip planning and fuel calculations. Note that the UK is a partial case: it uses miles for road distances and speeds while using metric for most other purposes.

The nautical mile is a separate unit entirely and should not be confused with this one. At 1,852 metres it is about 15% longer than a statute mile, and it is defined as one minute of latitude, which is why it remains standard in marine and air navigation. Converting a nautical mile with the 1.609344 factor gives a meaningfully wrong answer.