Speed Unit Converter
Convert speed between km/h, mph, m/s, feet per second and knots with exact factors.
How it works
m/s = value × factor(from) · result = (m/s) ÷ factor(to) (1 mph = 0.44704 m/s, 1 km/h = 1/3.6 m/s)
Speed is distance over time, so every unit converts through metres per second. A km/h is one kilometre (1000 m) per hour (3600 s), giving exactly 1/3.6 m/s; an mph is 1609.344 m per 3600 s = 0.44704 m/s. A knot is one nautical mile per hour, 1852/3600 = 0.5144 m/s, which is why it is standard in air and sea navigation.
Worked example
Convert 100 km/h to mph: 100 × (1/3.6) = 27.778 m/s, then 27.778 ÷ 0.44704 ≈ 62.14 mph. A common highway speed is therefore about 62 mph.
Sources: Knot (unit) — Wikipedia
Frequently asked questions
How do I convert km/h to mph quickly?
Multiply km/h by about 0.621 (or divide by 1.609). So 100 km/h ≈ 62 mph and 50 km/h ≈ 31 mph. The exact factor comes from a mile being 1.609344 km.
What is a knot?
A knot is one nautical mile per hour, equal to about 1.852 km/h or 0.514 m/s. It is the standard speed unit in aviation and maritime navigation because it ties directly to latitude.
How fast is 1 m/s in km/h?
Exactly 3.6 km/h, because one metre per second covers 3600 metres in an hour, which is 3.6 kilometres.
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This calculator is for educational purposes. Double-check important results before acting on them.