Miles per hour

This article is about the unit of speed. For the comic book, see MPH (comics). For other uses, see MPH.

Miles per hour (mph, m.p.h., MPH, or mi/h) is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom, the United States, and a number of smaller countries, most of which are UK or US territories, or have close historical ties with the UK or US.

miles per hour
Speedometer, indicating speed in miles per hour
General information
Unit system	Imperial, United States customary units
Unit of	speed
Symbol	mph
Conversions
1 mph in ...	... is equal to ...
km/h	1.609344
m/s	0.44704

Usage

Speed limit units on traffic signs around the world:

  Kilometres per hour (km/h)

  Miles per hour (mph)

  Both

  none known

50 mph speed limit sign in the United Kingdom

65 mph speed limit sign in the United States

Road traffic

Speed limits and road traffic speeds are given in miles per hour in the following jurisdictions:

• Antigua and Barbuda
• Bahamas^[1]
• Belize^[2]
• Dominica^[3]
• Grenada^[4]
• Liberia (occasionally)^[14]
• Marshall Islands
• Micronesia
• Palau
• Saint Kitts and Nevis^[15]
• Saint Lucia^[16]
• Saint Vincent and the Grenadines^[17]
• United Kingdom^[18]
• The following British Overseas Territories:
  • Anguilla^[19]
  • British Virgin Islands^[20][21]
  • British Indian Ocean Territory
  • Cayman Islands^[22]
  • Falkland Islands^[23]
  • Montserrat
  • Saint Helena, Ascension and Tristan da Cunha^[24]
  • Turks and Caicos Islands^[25]
• The Crown dependencies:
  • Bailiwick of Guernsey
  • Isle of Man
  • Jersey
• United States^[26]
• The following United States overseas dependencies:
  • American Samoa^[27]
  • Guam^[28]
  • Northern Mariana Islands^[29]
  • Puerto Rico
  • United States Virgin Islands^[30][31]

Rail networks

Miles per hour is the unit used on the US, Canadian and Irish rail systems.^[32][33][34] Miles per hour is also used on British rail systems, excluding trams, some light metro systems, the Channel Tunnel and High Speed 1.^[35]

Nautical and aeronautical usage

Nautical and aeronautical applications favour the knot as a common unit of speed. (One knot is one nautical mile per hour, with a nautical mile being exactly 1,852 metres or about 6,076 feet.)

Other usage

In some countries mph may be used to express the speed of delivery of a ball in sporting events such as cricket, tennis and baseball.

Conversions

1 mph	= 0.44704 m/s (exactly)
	= 1.609344 km/h (exactly)

Conversions between common units of speed

	m/s	km/h	mph (mi/h)	knot	fps (ft/s)
1 m/s =	1	3.600000	2.236936*	1.943844*	3.280840*
1 km/h =	0.277778*	1	0.621371*	0.539957*	0.911344*
1 mph (mi/h) =	0.44704	1.609344	1	0.868976*	1.466667*
1 knot =	0.514444*	1.852	1.150779*	1	1.687810*
1 fps (ft/s) =	0.3048	1.09728	0.681818*	0.592484*	1

(* = approximate values)

See also

• Kilometres per hour
• Acceleration
• Velocity