Kilometres per hour

Speed limit in km/h on a road in Denmark.

The kilometre per hour or kilometer per hour (symbol: km/h, km h^-1 or km·h⁻¹) is a unit of speed or velocity.

Definition

Speed limit units on traffic signs around the world:

  Kilometers per hour (km/h)

  Miles per hour (mph)

  Both

  No speed limit units

By definition, an object travelling at a speed of 1 km/h in a straight line for one hour moves one kilometre. The unit is the most commonly used unit of speed worldwide, more common than the SI unit of speed, metre per second (m/s or m s^-1).

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

Related pages

• Kinematics