Mile per hour

Miles per hour is an imperial unit of speed expressing the number of statute miles covered in one hour. It is currently the standard unit used for speed limits, and to express speeds generally, in many countries throughout the world.

These include roads in the United Kingdom, the United States,[1][2] American Samoa,[3] the Bahamas,[4] Belize,[5] British Virgin Islands,[6] the Cayman Islands,[7] Dominica,[8] the Falkland Islands,[9] Grenada,[10] Guam,[11] Myanmar,[12] The N. Mariana Islands,[13] Samoa,[14] St. Lucia,[15] St. Vincent & The Grenadines,[16] St. Helena,[17] St. Kitts & Nevis,[18] Turks & Caicos Islands,[19] the U.S. Virgin Islands,[20][21]Antigua & Barbuda (although km are used for distance),[22] and Puerto Rico (same as former).[23]

Miles per hour are also used in the Canadian rail system.[24] In some countries it may be used to express the speed of delivery of a ball in sporting events such as cricket, tennis, and baseball. A common abbreviation is mph or MPH.

Road traffic speeds in other countries are quoted in km/h. Occasionally, however, both systems are used: for example, in Ireland, a judge considered a speeding case by examining speeds in both kilometres per hour and miles per hour. The judge was quoted as saying the speed seemed "very excessive" at 180 km/h but did not look "as bad" at 112 mph; a reduced fine was still imposed on the speeding driver.[25] In addition, there are two examples of km and MPH used side by side above.

Nautical and aeronautical applications, however, favour the knot as a common unit of speed: one knot is one nautical mile per hour.


1 mph is equal to:

  • SI derived unit
  • km/h
  • feet per second (= 22/15 feet per second)
  • approx. 0.868976 knots

When converting miles per hour to another unit of measurement, or vice versa, it helps to know exactly how miles and hours are related to other units of distance and time, respectively. For example, 1 mile is equal to 5,280 feet, 1,760 yards, or 1,609.344 metres. Likewise, 1 hour is equal to 60 minutes, or 3,600 seconds.

Conversions between common units of speed
m/s km/h mph knot ft/s
1 m/s = 1 3.6 2.236936 1.943844 3.280840
1 km/h = 0.277778 1 0.621371 0.539957 0.911344
1 mph = 0.44704 1.609344 1 0.868976 1.466667
1 knot = 0.514444 1.852 1.150779 1 1.687810
1 ft/s = 0.3048 1.09728 0.681818 0.592484 1
(Values in bold face are exact.)

See also


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