Convert kilometers to miles (and miles back to km) in one step.
| Kilometers | Miles | Context |
|---|---|---|
| 1 km | 0.621 mi | 1,000 meters |
| 5 km | 3.107 mi | 5K race |
| 10 km | 6.214 mi | 10K race |
| 21.1 km | 13.1 mi | Half marathon |
| 42.2 km | 26.2 mi | Marathon |
| 100 km | 62.1 mi | 100K ultramarathon |
miles = km × 0.621371. Or: km = miles × 1.60934.
Multiply km by 0.6 for a fast mental approximation. 10 km × 0.6 = 6 miles (actual: 6.21).
100 km/h = 62.1 mph. European 130 km/h = 80.8 mph. US 60 mph = 96.6 km/h.
A 5K race is 5 km = 3.11 miles. A marathon is 42.195 km = 26.219 miles.
One kilometer is equal to 0.621371 miles (approximately 0.621 miles or 5/8 of a mile). Conversely, 1 mile = 1.60934 km. The mile is defined as exactly 1,609.344 meters (or 1.609344 km) by international agreement since 1959. One kilometer = 1,000 meters. This means 1 mile ≈ 1.609 km, making a mile about 60.9% longer than a kilometer.
10 km = 6.214 miles. This is the distance of a 10K race, one of the most popular road racing distances worldwide. For context: 10 km takes approximately 50–60 minutes for a recreational runner (6–7 min/km pace), 40–45 minutes for a fit runner, and under 30 minutes for competitive runners. The world record for 10 km road racing is 26:24 (men, Rhonex Kipruto, 2020) and 29:14 (women, Agnes Ngetich, 2025).
5 km = 3.107 miles. This is the standard 5K race distance, one of the most popular running event distances globally. The 5K is roughly the distance of running 12.5 laps around a standard 400-meter track. Average 5K completion times range from 25–35 minutes for recreational runners to under 15 minutes for elite athletes. The world road record is 12:49 (men, Kibel Kandie, 2020).
Multiply km/h by 0.621371 to get mph. Common speed conversions: 30 km/h = 18.6 mph (urban speed limit in Europe). 50 km/h = 31.1 mph. 100 km/h = 62.1 mph (common highway speed in metric countries). 120 km/h = 74.6 mph. 130 km/h = 80.8 mph (German Autobahn advisory speed). For the reverse: multiply mph by 1.60934 to get km/h. 60 mph = 96.6 km/h. 70 mph = 112.7 km/h.
Kilometers are part of the metric system, used officially by every country in the world except the United States, Liberia, and Myanmar (for road distances). The United Kingdom officially uses kilometers for road signs only in a few places — most UK road distances remain in miles despite metric adoption for most other measurements. The US, which standardized its measurement system before metric adoption, has never transitioned road distances to kilometers due to the enormous cost of replacing signs and changing public habits.
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