Kilometre Per Hour (km/h) Conversions
The kilometre per hour (SI symbol: km/h; abbreviations: kph, kmph, km/hr) is a unit of speed, expressing the number of kilometres travelled in one hour. Although the metre was formally defined in 1799, the term "kilometres per hour" did not come into immediate use – the myriametre (10,000 metres) and myriametre per hour were preferred to kilometres and kilometres per hour.
Internationally, km/h is the most commonly used unit of speed on traffic signs and road vehicle speedometers. The SI representations, classified as symbols, are "km/h", "km h-1" and "km·h-1". Several other representations of "kilometres per hour" have been used since the term was introduced and many are still in use today; for example, dictionaries list "km/h", "kmph" and "km/hr" as English abbreviations.