Convert Kilometer to Mile
Conversion Formula
mi = km × 0.621371To convert Kilometer to Mile, use the formula above. This is the standard conversion factor used worldwide.
Conversion Table
| Kilometer (km) | Mile (mi) |
|---|---|
| 1 | 0.621371 |
| 5 | 3.106855 |
| 10 | 6.213710 |
| 100 | 62.137100 |
Why convert Kilometer to Mile
Road signs outside the US and the UK are in kilometers, so travelers driving a rental car abroad convert posted speed limits and distances against a mile-based speedometer or habit. Runners are the other major audience: race distances are set in kilometers worldwide, and a runner training for a 10K or marathon wants to know what that distance means in the miles their US app reports.
Where the number comes from
A mile has been defined as exactly 1,609.344 meters since the same 1959 agreement that fixed the inch and the foot, so a mile is also exactly 1.609344 kilometers. Nothing about this conversion is approximate, though because the factor carries six decimal places, most everyday conversions round it to 0.6214 miles per kilometer without meaningfully affecting the result.
Quick reference
| 1 km | 0.6214 mi | |
| 1 mi | 1.6093 km | exact ratio is 1.609344 |
| 5 km | 3.107 mi | a 5K race |
| 10 km | 6.214 mi | a 10K race |
| 42.195 km | 26.219 mi | marathon distance |
| 100 km/h | 62.14 mph | a common European speed limit |
Common mistakes
- Runners converting a marathon (42.195 km) sometimes round both the distance and the factor and land on a number visibly different from the standard 26.219 miles, which matters when comparing a finish time to a published pace chart.
- Drivers also mix up the direction under time pressure, reading a 100 km/h sign and comparing it directly to a 100 mph speedometer instead of converting it down to roughly 62 mph first.
Frequently Asked Questions
Why is a marathon 26.219 miles and not a round number?
The marathon distance was fixed at 42.195 km in 1921 to match the extended course used at the 1908 London Olympics, and that figure converts to a non-round mile distance rather than the other way around.
What's a fast mental shortcut for km to miles?
Multiply kilometers by 0.6, which understates the true figure by about 3 percent, close enough for a rough sense of distance but not for pace math.
How do I convert a kilometer-based speed limit to mph while driving?
Multiply the km/h figure by 0.6214, or use the shortcut of taking roughly five eighths of the number for a fast estimate.
Is a nautical mile the same as the mile used in this conversion?
No. A nautical mile is 1,852 meters, about 15 percent longer than the statute mile this page converts, and it's used for maritime and aviation navigation rather than road or running distances.