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.

Usage

[Speed limit units on traffic signs around the world:

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Road traffic

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

Rail networks

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

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