km/h, mph and knots: converting speeds
A mile per hour is exactly 1.609344 km/h, and a knot is 1.852 km/h. To go from mph to km/h, multiply by 1.609344; for knots, multiply by 1.852.
Updated November 6, 2026 · Sources
The definitions
- 1 mile = 1,609.344 m, so 1 mph = 1.609344 km/h.
- 1 nautical mile = 1,852 m, and 1 knot = 1 nautical mile per hour = 1.852 km/h.
- 1 m/s = 3.6 km/h, because an hour has 3,600 seconds and a kilometer 1,000 meters.
Examples
100 km/h = 62.14 mph. 65 mph = 104.6 km/h. 20 knots = 37.04 km/h.
90 km/h = 90 ÷ 3.6 = 25 m/s, and 10 m/s = 36 km/h.
| km/h | mph | knots | m/s |
|---|---|---|---|
| 30 km/h | 18.6 | 16.2 | 8.3 |
| 50 km/h | 31.1 | 27 | 13.9 |
| 80 km/h | 49.7 | 43.2 | 22.2 |
| 90 km/h | 55.9 | 48.6 | 25 |
| 100 km/h | 62.1 | 54 | 27.8 |
| 110 km/h | 68.4 | 59.4 | 30.6 |
| 120 km/h | 74.6 | 64.8 | 33.3 |
| 130 km/h | 80.8 | 70.2 | 36.1 |
Mental math
Multiplying mph by 1.6 gives a good idea: 65 mph is about 104 km/h, against 104.6 km/h exactly.
Common mistakes
- Mixing up the statute mile (1,609.344 m) and the nautical mile (1,852 m).
- Saying “knots per hour”: a knot is already a speed, one nautical mile per hour.
- Forgetting that 1 m/s is 3.6 km/h, not 1.