A mile (mi) is a unit of length in the US customary and imperial systems of measurement. The definition of the mile has changed many times over the course of history as a result of changing definitions of the yard, the base unit of length in the US customary and imperial systems of measurement. The international mile, which will be referred to as simply "mile," is defined as:
1 mile = 5,280 feet = 1,760 yards
1 mile = 1609.344 meters
The mile is used mostly in the US, UK, and their territories. In contexts where these countries would use miles, most other countries use kilometers instead. For example, speed in the US is most commonly displayed in units of miles per hour (mph) rather than kilometers per hour (kph) elsewhere. Also, distances in sporting events such as marathons or bike races are commonly measured in miles, as compared to kilometers (km) elsewhere.
Other definitions of the mile
There are many historical definitions of a mile, most of which have been replaced by the international mile. Although the international mile is the standardized version of the mile, there are still some special cases where different definitions of the mile are used.
US survey mile:
A US survey mile, also referred to as the statute mile, was used for many years after the standardization of the mile. It differs only slightly from the international mile. Below are comparisons between the survey mile, meter, and international foot:
1 survey mile = 1609.347 meters = 5280.0098 feet
1 international mile = 1609.344 meters = 5280 feet
The continued use of the survey mile in the US post-standardization of the mile was due to there already being existing survey data based on the survey yard. Rather than risk any potential confusion or inaccuracies, the US chose to retain the survey foot, yard, and mile for surveying purposes while using the standardized definitions elsewhere.
The nautical mile is a measurement that was originally based on a minute of latitude.
1 US nautical mile = 1853.249 meters = 6080.2 feet
1 UK nautical mile = 1853.184 meters = 6080 feet