Quick answer
Enter a speed and select units. Key facts: 100 km/h = 62.14 mph, 1 mph = 1.609 km/h, 1 m/s = 3.6 km/h and 1 knot = 1.852 km/h.
- 1 mph:
- 1.609344 km/h
- 1 km/h:
- 0.621371 mph
- 1 m/s:
- 3.6 km/h
- 1 knot:
- 1.852 km/h
- Mach 1:
- ≈ 1,225 km/h at sea level
- Units:
- 6
Speed limits abroad, treadmill settings, wind forecasts and flight speeds all use different units. Our speed converter makes them instantly comparable.
How to use Speed Converter – step by step
- 1 Enter a speedType any value.
- 2 Pick unitse.g. km/h → mph.
- 3 CompareSee the speed in every unit.
Why use our Speed Converter?
Road & running
km/h, mph and m/s.
Sea & air
Knots and Mach.
Accurate
Exact mile and nautical mile definitions.
Instant
Real-time results.
Speed conversion charts
Kilometre per hour to Mile per hour
| Kilometre per hour (kmh) | Mile per hour (mph) |
|---|---|
| 10 kmh | 6.2137 mph |
| 30 kmh | 18.6411 mph |
| 50 kmh | 31.0686 mph |
| 60 kmh | 37.2823 mph |
| 80 kmh | 49.7097 mph |
| 100 kmh | 62.1371 mph |
| 120 kmh | 74.5645 mph |
Mile per hour to Kilometre per hour
| Mile per hour (mph) | Kilometre per hour (kmh) |
|---|---|
| 10 mph | 16.0934 kmh |
| 30 mph | 48.2803 kmh |
| 50 mph | 80.4672 kmh |
| 60 mph | 96.5606 kmh |
| 80 mph | 128.75 kmh |
| 100 mph | 160.93 kmh |
| 120 mph | 193.12 kmh |
About Mach numbers
Mach 1 is the speed of sound, which depends on air temperature. We use 340.29 m/s, the standard value at sea level and 15 °C.
Frequently asked questions
How do I convert km/h to mph?
Multiply by 0.621371. For example, 80 km/h ≈ 49.7 mph.
How do I convert m/s to km/h?
Multiply by 3.6.
What is a knot?
One nautical mile per hour (1.852 km/h), used at sea and in aviation.
How fast is Mach 1?
About 1,225 km/h or 761 mph at sea level.
Last updated November 2026 · Written and tested by the SmallEasyTools team.