Result = value × (factor of the unit you convert from) ÷ (factor of the unit you convert to), every factor being the size of the unit in m/s: 1 km/h = 0.27778 m/s 1 mph = 0.44704 m/s 1 knot = 0.51444 m/s 1 ft/s = 0.3048 m/s
Worked example
90 km/h = 90 × 0.27778 ÷ 1 = 25 m/s.
Quick reference
1 m/s = 3.6 km/h = 2.23694 mph = 1.94384 knot = 3.28084 ft/s
1 km/h = 0.27778 m/s = 0.62137 mph = 0.53996 knot = 0.91134 ft/s
Second worked example
60 mph = 60 × 0.44704 ÷ 0.2777778 = 96.5606 km/h.
Common values
Worked out with the same factors the converter uses.
10 km/h = 2.77778 m/s = 6.21371 mph = 5.39957 knot
30 km/h = 8.33333 m/s = 18.6411 mph = 16.1987 knot
50 km/h = 13.8889 m/s = 31.0686 mph = 26.9978 knot
60 km/h = 16.6667 m/s = 37.2823 mph = 32.3974 knot
80 km/h = 22.2222 m/s = 49.7097 mph = 43.1966 knot
100 km/h = 27.7778 m/s = 62.1371 mph = 53.9957 knot
120 km/h = 33.3333 m/s = 74.5645 mph = 64.7948 knot
Common mistakes
Multiplying by 3.6 when going from km/h to m/s. It is the other way: divide by 3.6 (or multiply by 5/18), so 72 km/h = 20 m/s.
Treating a knot as a mile per hour. The app uses 1 knot = 0.5144444 m/s and 1 mph = 0.44704 m/s, so a knot is about 1.15 mph.
Rounding 1 km/h to 0.28 m/s too early. At 120 km/h that gives 33.6 m/s instead of 33.33 m/s.
One of the unit converters in the Chemistry Calculator Suite,
alongside its chemistry, physics and maths tools. Nothing is behind a login and no value
you type is sent anywhere — the conversion runs in your own browser.
The Speed converter above is the live tool — it converts right here on the page. The link under it opens the full suite with this set already selected.