∑ Swippe

Speed Converter

Convert between mph, kph, knots, m/s, and more.

8 units
6 decimals

1 km/h = 0.621371 mph

About the speed converter

Convert speed and velocity between metric, imperial, US customary, and nautical systems. The SI derived unit is meter per second (m/s), but kilometers per hour and miles per hour are more common in everyday use. Knots are used in marine and aviation contexts.

Common conversions

mph to kph kph to mph

Frequently asked questions

  • How many miles per hour are in a kilometer per hour?

    One km/h equals approximately 0.621371 mph.

  • How many knots are in a mph?

    One mph equals approximately 0.868976 knots.

  • What is the speed of light in m/s?

    Exactly 299,792,458 m/s in vacuum — a defined constant in SI.

  • How fast is Mach 1?

    Mach 1 is the local speed of sound, approximately 343 m/s (767 mph) in dry air at 20 °C.

More common converters

Length → Weight and Mass → Volume → Temperature → Area → Pressure → Energy → Time →

Complete list of speed units