Length
Kilometers to miles: the simple conversion
One kilometre is about 0.621 miles. Here’s the exact formula, why it works, and a table for the distances you’ll actually use.
Quick answer
Multiply kilometres by 0.621371 to get miles.
The formula
miles = kilometers × 0.621371
kilometers = miles × 1.609344
These factors aren’t arbitrary: since 1959 the international mile has been defined as exactly 1,609.344 metres. A kilometre is 1,000 metres, so one kilometre is 1000 ÷ 1609.344 = 0.6213711922… of a mile.
Worked examples
- 100 km → miles: 100 × 0.621371 = 62.14 miles.
- A 5K race: 5 × 0.621371 = 3.11 miles.
- Speed, 100 km/h: the same factor applies — 100 km/h ≈ 62.1 mph.
| Kilometers | Miles |
|---|---|
| 1 | 0.621 |
| 5 (5K) | 3.107 |
| 10 (10K) | 6.214 |
| 21.0975 (half-marathon) | 13.109 |
| 42.195 (marathon) | 26.219 |
| 100 | 62.137 |
When you’ll use it
Most countries post road distances and speed limits in kilometres, while the US and UK use miles — so this is the conversion travellers reach for most. Runners use it to compare race distances, and it’s handy any time a fitness app reports the “wrong” unit.
Frequently asked questions
Is 1 km exactly 0.6214 miles?
Not exactly — that’s a rounded value. One kilometre equals 0.62137119… miles, because a mile is defined as exactly 1,609.344 metres. For everyday use, 0.6214 (or even 0.62) is close enough.
How many kilometres are in a mile?
Exactly 1.609344 km. So to go from miles to kilometres, multiply by about 1.609.
How far is a 5K in miles?
A 5-kilometre run is about 3.11 miles (5 × 0.621371). A 10K is about 6.21 miles.
Is a marathon really 26.2 miles?
Yes — a marathon is 42.195 km, which is 26.219 miles, almost always written as 26.2.