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Miles per hour

Automobile speedometer, indicating speed in miles per hour on the outer scale and kilometres per hour on the inner scale

Miles per hour (abbreviated mph, MPH or mi/h) is an imperial and United States customary unit of speed expressing the number of statute miles covered in one hour. Although kilometres per hour is now used worldwide, miles per hour remains the standard unit for speed limits in the United States, the United Kingdom, Antigua & Barbuda and Puerto Rico, although the latter two use kilometres for distances.


  • Roadway usage 1
  • Nautical and aeronautical usage 2
  • Conversions 3
  • See also 4
  • References 5

Roadway usage

These include roads in the United Kingdom,[1] the United States,[2] and UK and US territories; 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] Burma,[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), and Puerto Rico (same as former).

United States road sign with maximum speed noted in standard Mph

Miles per hour are also used in the Canadian rail system.[22] 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.

Road traffic speeds in other countries are quoted in kilometres per hour. 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.[23]

Nautical and aeronautical usage

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


1 mph = 0.44704 m/s (exactly)
= 1.609344 km/h (exactly)
≈ 1.467 ft/s (approximately)
0.868976 kn
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.)

1 Mph = 0.000277778 Mps (Miles Per Second)

Example: Apollo 11 attained speeds of 25,000 Mph, which converts to about 7 Mps. If Apollo 11 were to travel at 25,000 Mph from New York to Los Angeles it would reach Los Angeles in under 6 minutes.

See also


  1. ^ Speed limits (UK) Department for Transport. Retrieved 4 August 2015
  2. ^ "Modern Living: Think Metric". Time Magazine. 9 June 1975. Retrieved 15 June 2010. Meanwhile, the metricization of America is already taking place. Individual federal agencies, school systems, states and industries, as well as radio announcers, supermarkets, beverage bottlers and ballpark scoreboards, are hastening the everyday use of meters, liters and grams. ...a road sign outside Fergus Falls reads, ST. CLOUD 100 MILES OR 161 KILOMETERS. Other signs note that 55 m.p.h. equals 88 kilometers per hour. 
  3. ^ "Our Traffic Problems Are Going To Get Worse". Samoa News. 2013-06-03. Retrieved 2014-08-21. 
  4. ^ "The Nassau Guardian". The Nassau Guardian. Retrieved 2014-08-21. 
  5. ^
  6. ^ "Welcome to The BVI Beacon Online". 2005-12-01. Retrieved 2014-08-21. 
  7. ^ "Driver exceeded critical speed of 91 mph, jury hears :: Cayman Compass". Retrieved 2014-08-21. 
  8. ^ "Ophelia less organised but still a strong tropical storm". Dominica News Online. Retrieved 2014-08-21. 
  9. ^ "Columns - An Islander's offerings from Essex by James Marsh". 2012-04-19. Retrieved 2014-08-21. 
  10. ^ "George Grant - TROUBLESOME FIGURES". Grenada Broadcast. 2013-07-04. Retrieved 2014-08-21. 
  11. ^ "Maila Halom". Retrieved 2014-08-21. 
  12. ^ File:Naypyitaw Tollbooth.jpg
  13. ^ [2] Archived March 1, 2014 at the Wayback Machine
  14. ^ "Gale warning issued, Apia town drowns". 2013-02-02. Retrieved 2014-08-21. 
  15. ^ "The Voice - The national newspaper of St. Lucia since 1885". 2004-10-01. Retrieved 2014-08-21. 
  16. ^ Thursday, 21 August 2014 03:30:52 (AST) (2010-10-31). "St. Vincent appeals for aid as Tomas leaves ‘millions and millions’ in damage – I-Witness News". Retrieved 2014-08-21. 
  17. ^ "Flying Frenchman takes off in ‘overgrown pushchair’ | St Helena Online". 2012-10-23. Retrieved 2014-08-21. 
  18. ^ "Businesses Close Early Due to Passage of TS Isaac". The St. Kitts-Nevis Observer. 2012-08-22. Retrieved 2014-08-21. 
  19. ^ "Police urging motorists to slow down". 2009-07-15. Retrieved 2014-08-21. 
  20. ^ Conor Foley (Staff Writer) (2011-07-06). "Cops: Teen was driving 75 mph in city rollover crash". Virgin Islands Daily News. Retrieved 2014-08-21. 
  21. ^ JOY BLACKBURN (Daily News Staff) (2012-08-24). "Weather to begin clearing up today as Isaac leaves area - News". Virgin Islands Daily News. Retrieved 2014-08-21. 
  22. ^ "A. Classes of Track". Rules Respecting Track Safety. Transport Canada. 3 November 2008. Archived from the original on 2012-08-25.  Archived 25 August 2012.
  23. ^ "Another Metric System Fault". The New York Times. Associated Press. 1 November 2007. Retrieved 1 November 2010. 
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