When you need this conversion
Running and cycling (race distances are metric even in the US), driving abroad, reading maps and fitness apps set to a different region. Distances to cities, trail lengths and fuel ranges come up too.
Race distances
- 5K = 3.10686 mi
- 10K = 6.21371 mi
- Half marathon (21.0975 km) = 13.1094 mi
- Marathon (42.195 km) = 26.2188 mi
Mental shortcuts
The ratio of km to miles is close to the golden ratio, so consecutive Fibonacci numbers work as a rough guide: 5 mi ≈ 8 km, 8 mi ≈ 13 km, 13 mi ≈ 21 km. For anything precise, use the exact factor.
Common mistakes
Mixing up statute and nautical miles. A nautical mile is 1.852 km, used at sea and in aviation.
Converting speed as distance. km/h to mph uses the same factor, but see km/h to mph to avoid confusion.
For pacing, try the pace converter. For the reverse, use miles to km.