Speed Converter
Meters per second through Mach, plus a note on why Mach isn't a fixed speed and pace isn't a speed at all.
Most used speed tools
Kph to Mph
Road speeds, with the common European speed limits already worked out.
Knots to Mph
Marine and aviation speeds, with the Beaufort scale.
Km to Miles
Distance rather than speed.
Convert every unit at once
Enter a number.
Every speed converter on this site
Reference table
| Unit | In meters per second | Exact? |
|---|---|---|
| 1 km/h | 0.2777... m/s | Exact as 1/3.6 |
| 1 mph | 0.44704 m/s | Exact |
| 1 knot | 0.514444 m/s | Rounded, exactly 1852/3600 |
| 1 ft/s | 0.3048 m/s | Exact |
| Mach 1 at sea level, 15 °C | 340.29 m/s | Approximate, varies with conditions |
Mach isn't a fixed speed
Mach 1 is the local speed of sound, which depends on the temperature of the air, not on altitude directly. At sea level in a standard atmosphere at 15 °C it is about 340.3 m/s. In the cold air at cruising altitude it is closer to 295 m/s.
The figure in this tool uses the sea level standard value, so treat Mach output as indicative rather than exact. It is the one row here that isn't a fixed conversion.
Speed converts, pace doesn't
Distance per time converts as a straight ratio. Time per distance, which is how runners and cyclists usually think, doesn't: a 5 minute per kilometer pace is about 8 minutes 3 seconds per mile, because the longer unit takes more time rather than less.
Multiplying a per-kilometer pace by a distance factor gives a plausible wrong answer, the same trap as fuel economy.
Common questions
What is 100 km/h in mph?
100 kilometers per hour is 62.1 miles per hour. The mile is exactly 1,609.344 meters, giving a factor of 0.6213712, so this figure is exact to the digits shown.
Is a knot the same as a mile per hour?
No. A knot is one nautical mile per hour, and a nautical mile is 1,852 meters against 1,609 for a statute mile. One knot is about 1.151 mph.
How fast is Mach 1?
About 340 meters per second, or 761 mph, at sea level at 15 degrees Celsius. It falls in colder air, so there is no single figure.
Can I use this to convert running pace?
No. Pace is time per distance, the reciprocal of speed, so it doesn't convert with the same factors. This tool converts speed only.
Sources
- NIST Guide to the SI, Appendix B: Conversion Factors. National Institute of Standards and Technology. Source for every conversion factor on this page, and for which factors are exact rather than rounded.