Convert mile/hour to kilometer/hour

mile/hour

Definition: The unit miles per hour (symbol: mph) is a measurement of speed in the imperial and United States customary systems. It expresses the number of statute miles traveled over the period of one hour. One mph equals exactly 1.609344 kilometers per hour (km/h).

Current use: Along with km/h, mph is most typically used in relation to road traffic speeds. It is most widely used in the United States, the United Kingdom, and their related territories. It is also used in the Canadian rail system, though the Canadian road systems use km/h.

kilometer/hour

Definition: The unit kilometers per hour (symbol: km/h) is a unit of speed expressing the number of kilometers traveled in one hour.

History/origin: The unit of kilometers per hour is based on the meter, which was formally defined in 1799. According to the Oxford English Dictionary, the term kilometer first came into use in 1810. It was not until later in the mid-late 19th century however, that the use of kilometers per hour became more widespread; the myriametre (10,000 meters) per hour was preferred for expressing speed.

Current use: Km/h is currently the most commonly used unit of speed around the world and is typically used for car speeds and road signs. It is also common for both miles per hour as well as kilometers per hour to be displayed on car speedometers. There are many abbreviations for the unit kilometers per hour (kph, kmph, k.p.h, KMph., etc.), but "km/h" is the SI unit symbol.