๐ Speed Converter
Convert speed units in real time โ m/s, km/h, mph, knots, and ft/s. Useful for converting car speedometer readings, aviation/marine speeds (knots), or comparing sports records.
How to use
- Enter a value into any speed unit field (m/s, km/h, mph, kn, ft/s, etc.).
- The other unit fields update with the converted value in real time.
- To convert a different speed, just overwrite the number.
How the calculation works
Every speed is converted to metres per second first. One kilometre per hour is 1,000m รท 3,600s โ 0.2778 m/s, so multiplying m/s by 3.6 gives km/h. A mile per hour is 1,609.344m รท 3,600s. A knot is one nautical mile (1,852m) per hour. The nautical mile was originally defined as one minute of latitude on the Earth, which makes it convenient for navigation โ the reason aviation and shipping still use it. Feet per second is 0.3048m travelled each second, a unit you will see for things like ballistics and pitching speeds.
Worked example
Converting 100 km/h m/s: 100 รท 3.6 โ 27.78 mph: 100,000 รท 1,609.344 โ 62.14 Knots: 100 รท 1.852 โ 54.0 A US highway limit of 65 mph is about 104.6 km/h, and an airliner cruising at 500 knots covers 500 ร 1.852 = 926 km/h.
Things to be aware of
- A knot is already a speed (nautical miles per hour); "knots per hour" is incorrect.
- Aircraft have airspeed and groundspeed, which differ with the wind. This tool only converts units.
- Mach number depends on air temperature, so it cannot be converted with a fixed factor.
- To get an average speed from a race time, work out distance รท time in m/s first, then convert.
FAQ
What is a knot?
A speed unit used mainly for ships and aircraft; 1 knot equals about 1.852 km/h.
Can I convert mph road signs to km/h?
Yes โ convert freely between mph and km/h, which is handy when driving a rental car abroad.
Can I convert a running pace in m/s to km/h?
Yes โ enter a value in the m/s field and it converts to km/h automatically, useful for comparing running or cycling speeds.
Can I check a plane's cruising speed in km/h?
Yes โ enter the cruising speed in knots and see it instantly in km/h or mph.
Is this useful for a bike computer showing a different unit?
Yes โ converting between km/h and mph helps when reading a cycling computer imported from another country.