Conversion tool
Speed Converter
Convert between km/h, mph, m/s, knots, ft/s and Mach. All factors exact except Mach (speed of sound varies with temperature and altitude).
Formula & conversion factors
1 km/h = 1/3.6 m/s (exact)
1 mph = 0.44704 m/s (exact, derived from 1 mile = 1,609.344 m)
1 knot = 1,852/3,600 m/s (exact, 1 nautical mile per hour)
1 ft/s = 0.3048 m/s (exact)
Mach 1 ≈ 343 m/s (at sea level, 20 °C, dry air — approximate)
1 mph = 0.44704 m/s (exact, derived from 1 mile = 1,609.344 m)
1 knot = 1,852/3,600 m/s (exact, 1 nautical mile per hour)
1 ft/s = 0.3048 m/s (exact)
Mach 1 ≈ 343 m/s (at sea level, 20 °C, dry air — approximate)
1Worked example: 100 km/h in mph. 100 ÷ 3.6 = 27.778 m/s → ÷ 0.44704 = 62.137 mph (a common speed-limit conversion).
Reference standard: Base unit: metres per second (m/s), the SI derived unit of speed.
Mach number uses 343 m/s (speed of sound in dry air at 20 °C, sea level).
In practice, Mach varies with temperature and altitude.
Common questions
How do you convert km/h to mph?
Divide the km/h value by 1.60934. For a quick estimate: subtract about 38% from the km/h value.
What is a knot?
One knot equals one nautical mile (1,852 m) per hour. It is the standard speed unit in aviation and maritime navigation.