Speed Converter (km/h, mph, m/s, knots, Mach)
Convert a speed between km/h, mph, m/s, knots, and feet/second. Runs entirely in your browser.
How it works
Every unit is converted through a common base unit — meters per second. Mach is an exception: it's the ratio of a speed to the local speed of sound, which itself changes with air temperature and altitude. This converter uses the standard sea-level reference (340.3 m/s at 15°C), so treat Mach results here as approximate.
Common conversions
| From | To | Result |
|---|---|---|
| 100 km/h | mph | 62.14 mph |
| 60 mph | km/h | 96.56 km/h |
| 1 knot | km/h | 1.852 km/h |
| 343 m/s | km/h | 1234.8 km/h (speed of sound, ~20°C) |
FAQ
How many mph is 100 km/h?
About 62.14 mph.
Why is Mach only approximate here?
The speed of sound depends on air temperature (and, at altitude, air density) — it's about 340 m/s at sea level but noticeably slower at cruising altitude. A true Mach conversion needs the local speed of sound, not a fixed constant.