Miles to KM Converter – Miles to Kilometres and Back

How to use the miles to km converter

1. Choose mi → km or km → mi.
2. Type the distance.

You’ll get the converted distance, the same number as a speed (mph to km/h) and in nautical miles, plus a reference table.

The formulas

The same factors convert speeds: mph × 1.609344 = km/h.

Worked examples

• 10 miles = 16.09 km
• 5 km = 3.11 miles
• 26.2 miles (marathon) = 42.2 km
• 70 mph = 112.7 km/h

Common distances

Speed limits

The US and the UK use miles and mph on road signs; most other countries use kilometres and km/h.

Rounding

For driving, the nearest whole kilometre or mile is enough. For running, two decimal places make race distances recognisable: 3.11 miles is a 5K.

Nautical miles

Ships and aircraft use the nautical mile, which is exactly 1,852 metres — about 1.15 ordinary (statute) miles. Speeds at sea and in the air are given in knots, one nautical mile per hour.

Why there are two systems

The mile comes from the Roman mille passus, a thousand double steps. The kilometre was defined in France in the 1790s as part of the metric system, based on a fraction of the distance from the North Pole to the equator. Today the mile is defined as exactly 1,609.344 metres, so conversions between the two are precise.

Most of the world switched to kilometres during the twentieth century. The United States still uses miles for roads, and the United Kingdom uses miles on road signs while using metric units for most other things. Canada, Australia, Ireland, India and almost all of Africa use kilometres. If you drive abroad, remember that the number on the speed sign may be in a different unit from your car’s main speedometer scale.

Aviation and shipping use the nautical mile everywhere, whatever the country’s road signs say.

Tips for runners

Many training plans are written in miles, while race distances such as the 5K and 10K are metric. A GPS watch can show either; set it to match your plan so you don’t have to convert during a run. When switching, remember that a pace per mile is about 1.6 times your pace per kilometre — a 5:00 per km pace is about 8:03 per mile.

Where you’ll need it

• Running and cycling: race distances, training plans and GPS watches.
• Driving abroad: hire cars, road signs and fuel planning.
• Travel planning: distances between cities.
• Fitness trackers: switching between metric and imperial.

To work out your running pace per mile or per km, use the pace calculator. For fuel use, see the fuel economy converter; for shorter lengths, the feet to metres converter.