Speed Units Explained: km/h, mph, m/s, and Knots

Speed measures distance traveled per unit of time. Different units are used in different contexts — driving, athletics, maritime, and science each have preferred units.

Kilometers per hour (km/h): The standard road speed unit in most countries. 100 km/h is a typical highway speed limit. Used for vehicle specs, GPS devices, and weather wind speeds outside the US.

Miles per hour (mph): Road speed in the US and UK. 60 mph ≈ 96.6 km/h. To convert mph to km/h, multiply by 1.609. To convert km/h to mph, divide by 1.609 (roughly multiply by 0.62).

Meters per second (m/s): The SI scientific unit. Used in physics, engineering, and athletics (sprint speeds). 1 m/s = 3.6 km/h. A 100m sprint in 10 seconds = 10 m/s = 36 km/h.

Knots (kn): Used in maritime and aviation. 1 knot = 1 nautical mile per hour = 1.852 km/h = 1.151 mph. Knots are used because nautical charts measure distances in nautical miles (1 minute of latitude).

Feet per second (ft/s): Used in some engineering and ballistics contexts. 1 ft/s = 0.3048 m/s = 1.097 km/h.

Quick reference: Speed of sound at sea level ≈ 1,235 km/h (767 mph, 343 m/s, 667 knots). Commercial airliner cruising speed ≈ 900 km/h (560 mph, 490 knots).

Use Tooler's Speed Converter for instant conversions between all these units.