Convert mph, km/h, m/s, knots and other speed units
Speed measures how fast something moves over a certain distance in a certain amount of time. Common units include meters per second, kilometers per hour, miles per hour and knots.
Speed conversions are useful for travel, fitness, running pace comparisons, vehicle data, aviation, shipping and scientific work.
Speed measures how far something travels in a given amount of time. Different countries and industries use different units: road speeds are expressed in km/h in most countries and in mph in the United States and United Kingdom; aviation and maritime navigation use knots; physics and engineering typically use metres per second. This page covers the common speed units, conversion formulas, a reference table, and answers to frequently searched speed conversion questions.
The metric system is the standard for scientific work, athletics timing, and road speed limits in most countries. Its decimal structure makes conversions between units straightforward.
Metres per second (m/s) – the SI base unit of speed, used in physics, engineering, and sports science.
Kilometres per hour (km/h) – used for road speed limits and vehicle speeds in most countries outside the US and UK.
The imperial system remains in everyday use for road speeds in the United States, the United Kingdom, and a small number of other countries. It is also used in some aviation and sports contexts.
Miles per hour (mph) – used for road speed limits and vehicle speedometers in the US and UK.
Feet per second (ft/s) – used in physics, ballistics, and some engineering calculations.
Knots (kt) – one nautical mile per hour; the standard unit for wind speed and for maritime and aviation velocity internationally.
The table below covers common road and travel speeds with km/h, mph, and m/s equivalents.
| km/h | mph | m/s |
|---|---|---|
| 10 km/h | 6.21 mph | 2.78 m/s |
| 20 km/h | 12.43 mph | 5.56 m/s |
| 30 km/h | 18.64 mph | 8.33 m/s |
| 50 km/h | 31.07 mph | 13.89 m/s |
| 60 km/h | 37.28 mph | 16.67 m/s |
| 70 km/h | 43.50 mph | 19.44 m/s |
| 80 km/h | 49.71 mph | 22.22 m/s |
| 100 km/h | 62.14 mph | 27.78 m/s |
| 110 km/h | 68.35 mph | 30.56 m/s |
| 120 km/h | 74.56 mph | 33.33 m/s |
| 1 knot (1.852 km/h) | 1.151 mph | 0.514 m/s |
Road speed limits differ by country, with km/h used in most of the world and mph in the US and UK. Drivers travelling internationally or using a foreign vehicle need to convert between the two. The most common conversions are 100 km/h = 62 mph and 60 mph = 97 km/h.
Pilots and sailors measure speed in knots for international consistency. A commercial aircraft cruising at 500 knots is travelling at approximately 926 km/h or 575 mph.
Track and road running speeds are reported in km/h, mph, or minutes per kilometre/mile depending on the country. For running pace calculations, see the steps to miles calculator.
Physics and engineering use metres per second. Common reference values: sound travels at approximately 343 m/s (1235 km/h) at sea level; a skydiver in freefall reaches around 55 m/s (200 km/h); wind speed in weather reports is given in knots or km/h.
Multiply miles per hour by 1.60934 to get kilometres per hour.
Example: 60 mph × 1.60934 = 96.56 km/h.
Multiply kilometres per hour by 0.621371 to get miles per hour.
Example: 100 km/h × 0.621371 = 62.14 mph.
A knot is one nautical mile per hour. One nautical mile equals 1.852 kilometres, so:
Knots are the standard speed unit in aviation and maritime navigation worldwide.
Speed conversion is useful for travel, athletics, engineering, and navigating between countries that use different measurement systems. The formulas and reference table above cover the most common conversions between mph, km/h, m/s, and knots.