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Speed Converter

Convert speed values between metric, imperial, maritime, and acoustic units.

About this calculator

Convert speed between metric, imperial, and maritime units — km/h, mph, m/s, knots, and Mach.

How to use

  1. Enter the speed value.
  2. Select the unit you are converting from and to.
  3. Press Convert to see the result.

Tips

  • Unlike the other units here, Mach isn't a fixed conversion factor — the speed of sound changes with air temperature and altitude. This converter uses 343 m/s, the commonly cited reference for dry air at 20°C (68°F) at sea level; Mach 1 is slower at altitude or in colder air.