1 kilometer per hour = 0.6214 miles per hour
Convert kilometers per hour to miles per hour with an exact, internationally defined factor — 1 km/h = 1/3.6 m/s (exact).
kilometers per hour to miles per hour
Computed with the exact factor · NIST SP 811
| Kilometer per hour | Mile per hour |
|---|---|
| 0.5 km/h | 0.3107 mph |
| 1 km/h | 0.6214 mph |
| 2 km/h | 1.243 mph |
| 3 km/h | 1.864 mph |
| 5 km/h | 3.107 mph |
| 10 km/h | 6.214 mph |
| 25 km/h | 15.53 mph |
| 50 km/h | 31.07 mph |
| 100 km/h | 62.14 mph |
Exact factor details
- Exact factor
- 1 km/h = 0.6214 mph (exact definition)
- Significant digits
- up to 4 significant digits shown
- Data source
- NIST SP 811 — verified against official tables
Why km/h to mph trips people up
Speed conversions between kilometers per hour, miles per hour, and meters per second. Because the mile is exactly 1,609.344 meters, the km/h ↔ mph factor is exact: 1 mph = 1.609344 km/h. Kilometers per hour is the standard road speed unit outside the US and UK. Miles per hour remains the road speed unit in the US and UK.
Speed limits, treadmill displays, and weather reports mix these units constantly. A quick sanity check: 100 km/h is about 62 mph, and highway speeds of 120 km/h are about 75 mph. Runners more often need pace (minutes per kilometer) rather than speed — see the pace calculator for that.
Use the quick-reference table for the amounts people actually look up, and the converter above for everything in between. Both are computed from the same factor at full precision, so the table and the converter can never disagree — there is no second, rounded copy of the data anywhere on this page.
Frequently asked questions
Is the km/h to mph conversion exact?
Yes. 1 km/h = 1/3.6 m/s (exact) and 1 mph = 0.44704 m/s (exact) are exact definitions, so the conversion is exact — results are rounded only for readability.
How do I convert km/h to mph in my head?
Multiply km/h by 0.62 (or miles per hour by 1.6) for a close estimate.
Why do other sites show slightly different km/h to mph results?
They round at different steps. This page computes with the full-precision factor and rounds only the final displayed number, so small trailing digits can differ from sites that round earlier.