Speed Converter
Convert between km/h, mph, meters per second, knots and feet per second.
Enter your numbers to see the result.
Speed conversion factors
| From | To | Multiply by |
|---|---|---|
| km/h | mph | 0.621371 |
| mph | km/h | 1.609344 |
| m/s | km/h | 3.6 |
| knots | km/h | 1.852 |
| knots | mph | 1.15078 |
A 100 km/h speed limit is 100 × 0.621371 = 62.1 mph. A 70 mph limit is 112.7 km/h.
Where each unit is used
- km/h: road speeds in most of the world.
- mph: roads in the US and the UK.
- m/s: science, engineering and wind speed in weather data.
- Knots: one nautical mile per hour, used at sea and in aviation.
- Mach: multiples of the speed of sound, about 343 m/s (1,235 km/h) in dry air at 20 °C. It falls with temperature, so Mach 1 at cruising altitude is about 1,062 km/h.
Useful reference speeds
Walking pace is about 5 km/h (3 mph). A recreational cyclist rides at about 20 km/h. Usain Bolt's top speed was about 44.7 km/h (27.8 mph). A commercial jet cruises at about 900 km/h, or 480 knots.
Frequently asked questions
How do I convert km/h to mph?
Multiply by 0.621371, or divide by 1.609. 120 km/h is about 74.6 mph.
How do I convert m/s to km/h?
Multiply by 3.6. For example, 10 m/s is 36 km/h.
What is a knot?
A knot is one nautical mile per hour, equal to 1.852 km/h or about 1.15 mph.
Last reviewed Oct 20, 2026. Results are estimates; check important decisions with a qualified professional.