Speed Converter

Convert miles per hour, kilometers per hour, knots, meters per second and feet per second.

Decimals, fractions (3 1/2) and e-notation (1.5e6) all work.
Common Conversions
Significant Digits
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Result
Formula
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Exact?

In Every Unit

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How to Convert Speed Units

Speed is distance over time, so each factor comes from the length and time units: a mile per hour is 1,609.344 m ÷ 3,600 s = 0.44704 m/s exactly.

km/h = mph × 1.609344   mph = km/h ÷ 1.609344   km/h = m/s × 3.6

Worked Example

Common Conversions

FromEquals
1 mph1.609344 km/h
1 km/h0.6213712 mph
1 kn1.150779 mph
1 m/s3.6 km/h
1 mph1.466667 ft/s
1 kn1.852 km/h

Unit Definitions

UnitEqualsExact?
Meters per second (m/s)1 m/sExact
Kilometers per hour (km/h)0.2777777778 m/sExact
Miles per hour (mph)0.44704 m/sExact
Knots (kn)0.5144444444 m/sExact
Feet per second (ft/s)0.3048 m/sExact
Feet per minute (ft/min)0.00508 m/sExact
Meters per minute (m/min)0.01666666667 m/sExact
Speed of light (c)299,792,458 m/sExact

Factors follow NIST Special Publication 811, Appendix B. "Exact" means the unit is defined as that value; results are rounded only for display.

Tips

A knot is one nautical mile per hour, about 1.15 mph. Mach number isn't included because the speed of sound changes with air temperature.