Speed converter
Type a speed, choose the units, and see the result and the same speed in every common unit. A mile per hour is exactly 0.44704 m/s and a knot is exactly one nautical mile per hour.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Type a number. A dot or a comma works as the decimal separator.
- Choose the unit you have and the unit you need. The ⇄ button swaps them.
- The table below shows the same speed in all common units at once.
Conversion factors
Every unit is converted through meters per second. Each factor follows from an exact length definition divided by a number of seconds.
| Unit |
In m/s |
| 1 km/h = 1,000 m ÷ 3,600 s |
0.2777… m/s |
| 1 mph = 1,609.344 m ÷ 3,600 s |
0.44704 m/s |
| 1 knot = 1,852 m ÷ 3,600 s |
0.5144… m/s |
| 1 ft/s |
0.3048 m/s |
| speed of light, c |
299,792,458 m/s |
Worked example
The speed limit is 120 km/h. In miles per hour that is 120 ÷ 1.609344 = 74.56 mph. A ship making 18 knots travels 18 × 1.852 = 33.34 km/h.
Quick reference
- 1 m/s = 3.6 km/h ≈ 2.2369 mph
- 1 mph ≈ 1.6093 km/h
- 1 knot ≈ 1.852 km/h ≈ 1.1508 mph
- 30 mph ≈ 48.28 km/h, 60 mph ≈ 96.56 km/h
Frequently asked questions
How do I convert km/h to mph?
Divide by 1.609344, or multiply by about 0.6214. For example, 100 km/h ÷ 1.609344 = 62.14 mph.
How do I convert mph to km/h?
Multiply by 1.609344. For example, 70 mph × 1.609344 = 112.65 km/h.
How do I convert m/s to km/h?
Multiply by 3.6, because an hour has 3,600 seconds and a kilometer has 1,000 meters. 10 m/s is 36 km/h.
What is a knot?
One nautical mile per hour, exactly 1.852 km/h or about 1.1508 mph. It is used in aviation and at sea.
Does the converter include Mach?
No. Mach is a ratio to the speed of sound, which changes with temperature and altitude, so it has no single conversion factor.