UnitSnapSpeed converter
Speed is distance traveled per unit of time. The SI unit is the meter per second (m/s). Road speeds are usually given in kilometers per hour, where 1 m/s equals exactly 3.6 km/h, or in miles per hour in the United States and the United Kingdom. Scientific work generally uses m/s or km/s.
Convert between 10 speed units. Pick any two units below; results update as you type.
Popular speed conversions
- Kilometers per Hour to Miles per Hour
- Miles per Hour to Kilometers per Hour
- Meters per Second to Kilometers per Hour
- Kilometers per Hour to Meters per Second
- Meters per Second to Miles per Hour
- Miles per Hour to Meters per Second
- Knots to Kilometers per Hour
- Kilometers per Hour to Knots
- Knots to Miles per Hour
- Miles per Hour to Knots
- Feet per Second to Meters per Second
- Meters per Second to Feet per Second
- Mach (at 20 °C) to Kilometers per Hour
- Kilometers per Hour to Mach (at 20 °C)
About speed units
Ships and aircraft use the knot, one nautical mile per hour, which is exactly 1.852 km/h. One mile per hour is exactly 1.609344 km/h. Mach number expresses speed relative to the speed of sound, which depends on air temperature; this converter uses 343 m/s, the approximate speed of sound in dry air at 20 °C.
Because the speed of sound falls as air gets colder, Mach 1 at cruising altitude is slower in absolute terms than Mach 1 at sea level on a warm day. Treat Mach conversions here as approximations for standard room-temperature air.
Tips
- To estimate km/h from mph, multiply by about 1.6; to go the other way, multiply by about 0.62.
- Divide km/h by 3.6 to get m/s exactly, a common step in physics problems.
- Knots are based on the nautical mile (1,852 m), not the statute mile, so they are not interchangeable with mph.
All speed units
| Unit | Symbol | Value in meters per second |
|---|---|---|
| Meters per Second | m/s | 1 m/s = 1 m/s |
| Feet per Second | ft/s | 1 ft/s = 0.3048 m/s |
| Kilometers per Second | km/s | 1 km/s = 1,000 m/s |
| Meters per Minute | m/min | 1 m/min = 0.01666667 m/s |
| Feet per Minute | ft/min | 1 ft/min = 0.00508 m/s |
| Kilometers per Minute | km/min | 1 km/min = 16.66667 m/s |
| Kilometers per Hour | km/h | 1 km/h = 0.2777778 m/s |
| Miles per Hour | mph | 1 mph = 0.44704 m/s |
| Knots | kn | 1 kn = 0.5144444 m/s |
| Mach (at 20 °C) | Ma | 1 Ma = 343 m/s |
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Factors: NIST SP 811 · SI Brochure · NIST Handbook 44 — Updated