Speed Converter
Convert between speed units instantly: m/s, km/h, mph, knots, ft/s, and Mach. Free, 100% in your browser.
Reference
How does speed conversion work?
Speed conversion uses fixed ratios between units. This tool converts through meters per second (m/s) as the base unit. 1 km/h = 1/3.6 m/s, 1 mph = 0.44704 m/s exactly, 1 knot = 0.514444 m/s (1 nautical mile per hour), and Mach 1 ≈ 340.29 m/s (speed of sound at sea level, 15°C). All conversions are instantaneous and exact (except Mach, which varies with temperature and altitude).
Unit reference
SI unit: meters per second (m/s) — the standard unit of speed in physics. Metric: kilometers per hour (km/h) — used for road speeds in most countries. Imperial: miles per hour (mph) — used in the US, UK, and a few other countries. Nautical: knot (kn) = 1 nautical mile/hour — used in aviation and maritime navigation. Mach — ratio to the speed of sound, used in aeronautics. ft/s — feet per second, used in ballistics and some engineering contexts.
Common use cases
Driving — convert speed limits when traveling between countries (km/h ↔ mph). Aviation — convert between knots, km/h, and Mach for flight planning. Science — convert experimental velocities to SI units. Sports — compare running, cycling, or swimming speeds across different unit systems. Weather — convert wind speeds between m/s, km/h, and knots.
Privacy
All calculations run 100% in your browser. No data is sent to any server.