Convert miles per hour to kilometers per hour
1 mph = 1.609344 km/h · Formula and table below. Converting the other way? km/h to mph: Kilometers per Hour to Miles per Hour →
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Other units
- Meter per second (m/s) 0.44704
- Kilometer per hour (km/h) 1.609344
- Mile per hour (mph) 1
- Foot per second (ft/s) 1.466667
- Knot (kn) 0.868976242
Reviewed on by the Skala Convert team
One mile per hour equals exactly 1.609344 km/h.
What is 1 mph in km/h?
One mile per hour equals exactly 1.609344 km/h — the same factor as miles to kilometers, since the time unit is identical on both sides. Common limits:
| mph | km/h |
|---|---|
| 30 | 48.3 |
| 55 | 88.5 |
| 65 | 104.6 |
| 70 | 112.7 |
What speed is "10" on an American treadmill?
16.1 km/h. Treadmills built for the US market default to mph, and a runner who sets 10 expecting 10 km/h gets marathon pace instead — fast enough to end the session badly. If the display has a units toggle, this is the one setting worth checking before starting. A comfortable 10 km/h is 6.2 on an mph display.
Why does my speedometer read higher than my GPS?
By design and by law. Regulations including the UNECE R39 standard used across Europe require that a speedometer never read below actual speed, and allow it to read high — up to 10 percent plus 4 km/h. At a true 100 km/h, the dash may legally show anything from 100 to 114.
The tolerance exists because tire diameter changes with wear, pressure, and replacement, and a speedometer calibrated for a fresh tire would otherwise under-read as the tread wore down. GPS measures ground speed directly and does not care about your tires, which is why the two disagree and the GPS is usually right.
What mistakes do people make converting mph to km/h?
Converting the displayed number and treating the result as true speed. The conversion is exact; the input is not. If you need actual speed, start from GPS, not from the dash.
Who defines the mile per hour?
It inherits its value from the mile: NIST Special Publication 811, the US guide to the SI gives the mile as exactly 1,609.344 m, so one mile per hour is exactly 1.609344 km/h. For vehicles, UNECE Regulation No. 39 sets how speedometers must display speed, including the requirement never to show less than the true speed.
Formula
Kilometers per hour = Miles per hour × 1.609344
10 mph = 16.09344 km/h
Conversion table
| mph | km/h |
|---|---|
| 1 | 1.609344 |
| 2 | 3.218688 |
| 5 | 8.04672 |
| 10 | 16.09344 |
| 20 | 32.18688 |
| 25 | 40.2336 |
| 50 | 80.4672 |
| 100 | 160.9344 |
Frequently asked questions
What is 1 mph in km/h?
One mile per hour equals exactly 1.609344 km/h. A 70 mph limit is 112.7 km/h.
What speed is 10 on an American treadmill?
16.1 km/h, because US treadmills default to mph. A 10 km/h pace is 6.2 on an mph display.
Why does my speedometer read higher than GPS?
Regulations such as UNECE R39 require speedometers never to under-read and allow up to 10 percent plus 4 km/h over. The tolerance covers tire wear and pressure.