How to convert speed
- Type a speed in the Value box.
- Choose its unit, such as kilometres per hour.
- See it in metres per second, km/h, miles per hour, knots and feet per second, and copy what you need.
Conversion factors
| Unit | In metres per second |
|---|---|
| 1 km/h | 0.2778 m/s (1 ÷ 3.6) |
| 1 mph | 0.44704 m/s |
| 1 knot | 0.5144 m/s |
| 1 ft/s | 0.3048 m/s |
Because the mile and the foot are defined exactly in metres, these conversions are exact.
Quick reference
| km/h | mph | Context |
|---|---|---|
| 5 | 3.1 | Walking pace |
| 25 | 15.5 | Cycling |
| 50 | 31.1 | City speed limit in many countries |
| 100 | 62.1 | Motorway speed in many countries |
| 120 | 74.6 | Highway limit in some countries |
Speed limits abroad
Speed limit signs use km/h almost everywhere, but mph in the US and the UK. If you're driving a rental car abroad, check which unit your speedometer shows: many cars display both, with one on a smaller inner scale.
Physics and sport
Physics problems use metres per second, so you'll often need to convert from km/h: divide by 3.6. A sprinter running 100 m in 10 seconds averages 10 m/s, which is 36 km/h or about 22.4 mph.
Running pace is often given as minutes per kilometre or per mile instead of speed. A pace of 5:00 per km is 12 km/h, and 8:00 per mile is 7.5 mph.
Knots at sea and in the air
Ships and aircraft use knots, which are nautical miles per hour. Weather forecasts for sailing also give wind speeds in knots. One knot is about 1.852 km/h or 1.151 mph.
Related tools
For distances, use the length converter. Conversions happen in your browser.