Km to miles converter

The rule

One mile is exactly 1.609344 kilometers: 5,280 feet of exactly 0.3048 m each (NIST Handbook 44, Appendix C). So kilometers to miles: divide by 1.609344, which is about multiplying by 0.621371. Miles to kilometers: multiply by 1.609344.

Worked example

10 km ÷ 1.609344 = 6.2137 miles. Going back, 6.2137 × 1.609344 = 10 km. A 5K run is 3.1 miles, a half marathon (21.0975 km) is 13.1 miles and a marathon (42.195 km) is 26.2 miles.

Speeds work the same way

Kilometers per hour and miles per hour use the same factor: 100 km/h is 62.1 mph and 60 mph is 96.6 km/h. The answer card shows nautical miles too, which sailors and pilots use: 1 nautical mile is exactly 1,852 m. For speeds in knots or meters per second, use the unit converter.

A quick check in your head

Use the Fibonacci numbers: 5 km is about 3 miles, 8 km about 5 miles and 13 km about 8 miles. Or multiply kilometers by 6 and divide by 10: 10 km is about 6 miles. To go the other way, multiply miles by 1.6: 50 miles is about 80 km (exactly 80.47).

Rounding

The answer is worked out from the exact definition, then shown to 4 decimal places (6 significant figures for numbers below 1). It says "exactly" only when nothing was rounded.