Kilometres per hour

unit of speed
(Redirected from Kilometers per hour)

Kilometres per hour is a unit of measurement, which measures speed or velocity. The unit symbol is km/h or km·h−1. By definition, an object travelling at a speed of 1 km/h in a straight line for 1 hour moves 1 kilometre. The unit is the most commonly used unit of speed worldwide, more common than the SI unit of speed, metres per second.

Speed limit in km/h on a road in the Northern Territory, Australia. However, most of Australia has a maximum speed limit of only 110 km/h
Speed limit units on traffic signs around the world:
  Kilometers per hour (km/h)
  Miles per hour (mph)
  No speed limit units


  • 3.6 km/h ≡ 1 m/s, the SI unit of speed, metre per second
  • 1 km/h ≈ 0.277 78 m/s
  • 1 km/h ≈ 0.621 37 mph ≈ 0.911 34 feet per second
  • knot ≡ 1.852 km/h (exactly)
  • 1 mile = 1.609344 km (~1.61 km)
  • n km/h ≈ ( 1.61 * n ) mph (where n is a quantity of speed in km/h)
  • 1 mph = ~1.6 km/h

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