Formula
value in target unit = value × (m/s per source unit) ÷ (m/s per target unit)
- 1 km/h = 1/3.6 m/s
- 1 mph = 0.44704 m/s exactly
- 1 knot = 1 nautical mile per hour = 1.852 km/h
Convert to metres per second, then to the unit you want.
Worked example
100 km/h in mph
- Value
- 100
- From
- Kilometres per hour (km/h)
- To
- Miles per hour (mph)
Kilometres per hour to Miles per hour
62.1371192237 mph
In words: 100 km/h = 62.1371192237 mph
How it works
To convert m/s to km/h multiply by 3.6 (3,600 seconds in an hour ÷ 1,000 metres in a kilometre). A mile per hour is exactly 0.44704 m/s, so 100 km/h is about 62.14 mph.
A knot is one nautical mile per hour. A nautical mile is 1,852 m — roughly one minute of latitude — so a knot is about 1.15 mph. Aviation and shipping use knots; road speeds use km/h or mph. To work out a journey from a speed use the Speed, Time and Distance Calculator; for distances alone see Length Converter.
Assumptions and limits
- Mach number isn't included because it depends on temperature and altitude.
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