Speed converter
Convert between m/s, km/h, mph, ft/s, knots and Mach
Pick the units at both ends to see the result. The common conversions row covers pairs such as mph to km/h.
This affects display only. Conversion always uses full precision.
| Unit | Symbol | Result |
|---|---|---|
| Metre per second | m/s | |
| Kilometre per hour | km/h | |
| Mile per hour | mph | |
| Foot per second | ft/s | |
| Knot | kn | |
| Mach (approximate) | Ma |
Example
Input
100 km/h
Example result
m/s 27.7777777778 mph 62.1371192237 kn 53.9956803456 ft/s 91.1344415281
The Mach figure is a rough comparison only; the real speed of sound varies with temperature.
Technical details & limits
Conversions run through metres per second. A knot is 1852 metres per hour, mph is 0.44704 metres per second and ft/s is 0.3048. The Mach column uses a fixed 340.3 metres per second, the value for dry air at 15 °C at sea level.
About this tool
Enter a value and pick its unit to get metres per second, kilometres per hour, miles per hour, feet per second, knots and Mach at once. The first five are exact definitions; the Mach column uses a single fixed speed of sound and is a rough comparison only.
Use cases
- Convert mph in an overseas car review into km/h.
- Turn wind speed in metres per second into knots.
- Convert a feet-per-second measurement into metric units.
How to use
- Type a number. Decimals and scientific notation such as 1.5e3 are accepted.
- Pick the unit the value is in and the unit you want it in. The ⇄ button swaps the two.
- The summary line gives the target unit; the table below lists the remaining speed units, including Mach as a rough comparison.
- Adjust the significant digits for a shorter or longer number. The conversion itself always runs at full precision.
Notes
Mach is not a fixed quantity: the speed of sound changes with the temperature of the medium. This page uses 340.3 metres per second, the value for dry air at 15 °C at sea level, as a rough comparison rather than an engineering figure.
FAQ
- How do I convert kilometers per hour into meters per second?
- Divide kilometers per hour by 3.6 to obtain meters per second, so 36 kilometers per hour equals 10 meters per second. The relationship uses 3600 seconds per hour together with the meter-to-kilometer conversion. Check the direction of the conversion when comparing vehicle or sports data. Multiplying instead of dividing changes the result substantially, and a correct unit conversion does not independently verify the measured speed itself.
- How many kilometers per hour are in one knot?
- 1 knot equals 1.852 kilometers per hour because an international nautical mile is 1852 meters. This tool can also express the same speed in meters per second and other supported units. A knot measures speed rather than distance. Keep nautical miles and knots distinct when comparing navigation data, and do not use a distance value as a speed without also specifying the time over which it was traveled.
- Why does Mach conversion use 340.3 meters per second?
- This tool fixes 1 Mach at 340.3 meters per second, using a sea-level standard-atmosphere reference at 15 Celsius. Actual sound speed varies with conditions and the medium. The fixed conversion is therefore a reference calculation rather than a precise model for every altitude or temperature. Use the appropriate environmental sound speed when a physical application requires an accurate Mach number instead of this table's constant factor.
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Temperature converter
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