Speed Converter
Convert speeds between road, maritime, and scientific units.
Measurement guide
Speed Converter
Kilometers per hour are handy for road signs in many countries, while miles per hour are used in others. Knots turn up in aviation and marine navigation, and meters per second is common in science. This converter lets you move between these units without doing the arithmetic by hand.
How to use the converter
- 1Enter the speed value you want to convert. For an ordinary speed reading, use a nonnegative value.
- 2Pick the starting unit: meters per second, kilometers per hour, miles per hour, knots, or feet per second.
- 3Choose the unit you want as the result. The value updates automatically after a short pause.
- 4Use the reverse control to swap the units when you want to convert in the other direction.
The conversion math
Each supported unit is converted through meters per second, a standard SI unit for speed. The general calculation is:
value in m/s = input value × source unit factor
result = value in m/s ÷ target unit factor
1 mph = 0.44704 m/s
1 knot = 0.514444… m/s
1 km/h = 1 ÷ 3.6 m/s
1 ft/s = 0.3048 m/s · base unit: m/s
For example, 90 km/h is 25 m/s, which is about 55.92 mph. These are unit conversions only: they don't account for vehicle performance, wind, road conditions, or measurement error. Speed is a magnitude here; the tool does not calculate direction or velocity vectors.
Road travel
Compare a speed limit or vehicle reading shown in a different country's units.
Boating and aviation
Convert knots into familiar land-speed units for a quick reference.
Sports and training
Translate running, cycling, or swimming speed measurements between units.
Science and schoolwork
Check a calculation that uses SI units or feet per second.