Kilometres per hour

Speed limit in km/h on a road in the Northern Territory, Australia.

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 units on traffic signs around the world:

  Kilometres per hour (km/h)

  Miles per hour (mph)

  Both

  No speed limit units

Conversions

• 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
• 1 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

Other websites

• A conversion calculator for Units of Speed