About the Speed Converter
Speed is measured in many different units depending on the context — km/h for road traffic in most countries, mph in the US and UK, knots in aviation and maritime, m/s in science, and Mach for supersonic flight. Our speed converter handles all of these with instant, accurate results.
How it works
All speed units are normalised to metres per second (m/s) — the SI unit of velocity. Your input is first converted to m/s, then every other unit is derived from that base. Mach number uses the standard speed of sound at sea level (343 m/s). All calculations run in your browser.
Common conversions
100 km/h ≈ 62.14 mph ≈ 27.78 m/s ≈ 53.99 knots. The speed of sound (Mach 1) is approximately 1,235 km/h or 767 mph at sea level. Whether you are converting km/h to mph for a speedometer reading or knots to km/h for a sailing trip, this tool has you covered.