Speed Converter
Convert speeds between kilometres per hour, miles per hour, metres per second, knots, and feet per second. All units update as you type. Free, no signup.
What is Speed Converter?
Speed is measured in different units depending on context. Kilometres per hour (km/h) is the standard for road speeds in most countries. Miles per hour (mph) is used in the US, UK, and a few other countries for road speed. Metres per second (m/s) is the SI unit and is used in physics and engineering calculations. Knots (nautical miles per hour) are used in aviation and maritime navigation. Feet per second (ft/s) appears in some ballistics and engineering contexts.
Speed conversions are needed when reading international weather forecasts (wind speed in different units), comparing vehicle specifications across markets, understanding aircraft or ship performance data, and converting physics problems between SI and other unit systems. The most common conversion is km/h to mph for travellers and for vehicle speed comparisons.
Enter a speed value in any field and all other units update instantly. All calculations run locally in your browser with no data sent anywhere.
How to use
Frequently asked questions
100 km/h = 62.14 mph. A useful approximation: multiply km/h by 0.621 to get mph.
A knot is one nautical mile per hour. 1 knot = 1.852 km/h = 1.15078 mph. Nautical miles are based on the arc length of one minute of latitude.
At sea level and 20°C, the speed of sound is approximately 343 m/s = 1,235 km/h = 767 mph = 1,125 ft/s = 667 knots.
Yes. All conversions run in your browser. Nothing is sent to any server.