Speed Converter

Speed converter for driving, weather, and aviation — mph, km/h, and knots.

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Convert between kilometres per hour (km/h), miles per hour (mph), metres per second (m/s), knots and feet per second. Useful for speed limits, car specifications, weather forecasts, athletics and aviation.

Popular Speed Conversions

All Speed Units

Unit	Symbol	Definition
Meter per Second	m/s	The SI derived unit of speed.
Kilometer per Hour	km/h	Distance in kilometers covered in one hour.
Mile per Hour	mph	Distance in miles covered in one hour.
Knot	kn	Equal to one nautical mile per hour.
Foot per Second	ft/s	Distance in feet covered in one second.

How speed conversion works

Speed is distance divided by time, so every speed unit is a length unit over a time unit. The base unit here is metres per second (m/s).

1 km/h = 1/3.6 m/s = 0.2777778 m/s
1 mph = 0.44704 m/s (exact) = 1.609344 km/h
1 knot = 1 nautical mile per hour = 1.852 km/h = 0.5144444 m/s
1 ft/s = 0.3048 m/s (exact)

km/h to mph: multiply by 0.621371. mph to km/h: multiply by 1.609344. km/h to m/s: divide by 3.6. m/s to km/h: multiply by 3.6. Knots to km/h: multiply by 1.852.

Speed limit chart: km/h to mph

Common speed limits
Kilometer per Hour (km/h)	Mile per Hour (mph)
30 km/h	18.6411 mph
40 km/h	24.8548 mph
50 km/h	31.0686 mph
60 km/h	37.2823 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

Mental shortcut: to get mph from km/h, multiply by 0.6 (100 km/h ≈ 60 mph; exact 62.14). To get km/h from mph, multiply by 1.6.

Real-world speeds

Typical speeds
Activity	Speed	In km/h	In mph
Brisk walking	5 km/h	5 km/h	3.1069 mph
Cycling	20 km/h	20 km/h	12.427 mph
City traffic limit	50 km/h	50 km/h	31.069 mph
Motorway limit	120 km/h	120 km/h	74.565 mph
Sprinter at top speed	12 m/s	43.2 km/h	26.843 mph
Passenger jet cruise (about)	480 kn	888.96 km/h	552.37 mph

Where each unit is used

km/h: road signs and car speedometers in Pakistan and most countries.
mph: road speed limits in the US and UK, and car specifications from those markets.
m/s: physics, engineering, sports science and wind measurements in science contexts.
Knots: aviation, shipping and weather. A speed of 1 knot is 1 nautical mile (1,852 m) per hour.
ft/s: ballistics, projectile data and some engineering specifications.

Common mistakes to avoid

Using 3.6 the wrong way. Divide km/h by 3.6 to get m/s and multiply m/s by 3.6 to get km/h. A 20 m/s wind is 72 km/h.
Confusing "knots per hour". A knot already means nautical miles per hour, so the phrase "knots per hour" is incorrect and describes acceleration.
Speedometer error. Car speedometers commonly read slightly high. Use GPS speed for precise checks.
Mixing statute and nautical miles. 1 mph is 0.869 knots. Do not treat them as equal.

Exact conversion factors

Every unit in Meter per Seconds (m/s)
Unit	Symbol	Exact factor
Meter per Second	m/s	1 m/s = 1 m/s
Kilometer per Hour	km/h	1 km/h = 0.2777777778 m/s
Mile per Hour	mph	1 mph = 0.44704 m/s
Knot	kn	1 kn = 0.5144444444 m/s
Foot per Second	ft/s	1 ft/s = 0.3048 m/s

Sources: NIST Special Publication 811; the knot is defined from the international nautical mile of 1,852 m.

Frequently Asked Questions

How do I convert km/h to mph?

Multiply the speed in km/h by 0.621371. For example, 100 km/h = 62.137 mph.

How do I convert mph to km/h?

Multiply by 1.609344. For example, 60 mph = 96.561 km/h.

How do I convert km/h to m/s?

Divide by 3.6. For example, 72 km/h = 20 m/s.

How fast is 1 knot in km/h?

1 knot is exactly 1.852 km/h, or about 1.15 mph.

What is 120 km/h in mph?

120 km/h = 74.565 mph.

How many mph is 1 m/s?

1 m/s is 2.2369 mph or 3.6 km/h.

All Speed Conversions

Choose a starting unit to see every conversion available from it.

Meter per Second (m/s) converter

Kilometer per Hour (km/h) converter

Mile per Hour (mph) converter

Knot (kn) converter

Foot per Second (ft/s) converter