21 kilometers equals 13.05 miles. Convert 21 km to miles instantly — close to the half marathon distance of 21.1 km.
To convert kilometers to miles, divide by 1.60934 (or multiply by 0.621371). So 21 km ÷ 1.60934 = 13.05 miles. The conversion factor is based on the exact definition of the international mile (1 mile = 1,609.344 meters).
| Distance | km | miles |
|---|---|---|
| 1 km | — | 0.62 |
| 1 mile | 1.61 | — |
| 5K | — | 3.11 |
| 5 miles | 8.05 | — |
| 10K | — | 6.21 |
| 10 miles | 16.09 | — |
| Half Marathon | 21.1 | 13.11 |
| Marathon | 42.2 | 26.22 |
| 50K | — | 31.07 |
| 50 miles | 80.47 | — |
| 100K | — | 62.14 |
| 100 miles | 160.93 | — |