kilometre per hour
Unit whose name includes an SI unit and a non-SI unit accepted for use with the SI
| Name | Symbol | Quantity | SI units |
| kilometre per hour | km/h | speed | 1000⁄3600 m s-1 |
 The kilometre per hour, symbol km/h, is a non-SI unit of speed, accepted for use with the SI.One kilometre per hour is equal to 1000⁄3600 metres per second. |
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An object with a constant speed of one kilometre per hour moves a distance of one kilometre in one hour, or 1000⁄3600 metres in one second.
The kilometre per hour is derived from the metre (an SI base unit) and the hour (a non-SI unit accepted for use with the SI).
| Distance | ÷ Time | = Speed | SI units |
| 1 km | ÷ 1 h | = 1 km/h | = 1000⁄3600 m s-1 |
| 3.6 km | ÷ 1 h | = 3.6 km/h | = 3600⁄3600 m s-1 |
| 3600 m | ÷ 3600 s | = 3600⁄3600 m s-1 | = 1 m s-1 |
A speed of 3.6 km/h is equal to 1 m s-1.
The kilometre per hour is the unit of speed used on road signs and motor vehicle speedometers in most countries of the world.
90 km/h = 25 m s-1
Examples of motor vehicle speeds
| Expressed in km/h | SI base units |
| 18 km/h | 5 m s-1 |
| 36 km/h | 10 m s-1 |
| 54 km/h | 15 m s-1 |
| 72 km/h | 20 m s-1 |
| 90 km/h | 25 m s-1 |
| 108 km/h | 30 m s-1 |
Usage
Abbreviations, such as kph and kmph, should not be used in place of the symbol km/h.
