Speed Converter: km/h, mph, m/s, Knots

Last updated: October 2026

From

Formula

1 km/h = 0.6213712 mph

How far each goes in one second:

Walking 5 km/h · 1.39 m
Running 12 km/h · 3.33 m

At 1 km/h you cover 0.278 m every second (the blue lane).

All Results

m/s 0.277778

km/h 1

mph 0.621371

ft/s 0.911344

kn 0.539957

Ma 0.000816297

Quick Reference Table: Kilometer per hour → Mile per hour

Value (km/h)	Result (mph)
10 km/h	6.2137 mph
30 km/h	18.6411 mph
50 km/h	31.0686 mph
80 km/h	49.7097 mph
100 km/h	62.1371 mph
120 km/h	74.5645 mph
130 km/h	80.7783 mph
200 km/h	124.2742 mph
300 km/h	186.4114 mph

About Speed Conversions

You need to convert speeds for travel, sports, flying and sailing. The most common conversion is between kilometers per hour (km/h) and miles per hour (mph). One mile per hour equals exactly 1.609344 km/h. Meters per second (m/s) is the SI unit of speed, used in physics and engineering. One m/s equals 3.6 km/h. The knot, used at sea and in aviation, equals exactly one nautical mile per hour (1.852 km/h). The Mach number compares a speed with the speed of sound (about 340 m/s at sea level at 15 °C).

Everyday Speeds

From walking pace to the speed of light. Speed limits in towns are usually 50 km/h in Europe and 30 mph in the UK.

Motion	km/h	mph	m/s
Walking	5.04	3.132	1.4
Jogging	11.88	7.382	3.3
Cycling	20.16	12.53	5.6
Usain Bolt's top speed	44.64	27.74	12.4
Town speed limit (50 km/h)	50	31.07	13.89
Cheetah	104.4	64.87	29
Motorway (130 km/h)	130	80.78	36.11
Airliner cruising	900	559.2	250
Speed of sound (sea level)	1,235	767.3	343
Speed of light	1,079,000,000	670,600,000	299,792,458

History of measuring speed

Speed is distance divided by time, so almost every unit of speed borrows a unit of length and one of time. The fastest speed of all, the speed of light, now defines the meter itself.

1676 Ole Rømer showed, from the timing of eclipses of Jupiter's moon Io, that light does not arrive instantly: it takes time to cross space.
1929 An international hydrographic conference in Monaco adopted an international nautical mile of 1,852 m; a knot is one nautical mile per hour.
1947 Chuck Yeager flew the Bell X-1 faster than the speed of sound in level flight, the first time a crewed aircraft had done so.
1983 The speed of light in a vacuum was fixed at exactly 299,792,458 meters per second, and the meter was defined through it.

Sources:

Length & Distance Time