The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a British imperial unit and US customary unit of distance; both are based on the older English unit of length equal to 5,280 English feet, or 1,760 yards. The statute mile was standardised between the British Commonwealth and the United States by an international agreement in 1959, when it was formally redefined with respect to SI units as exactly 1,609.344 metres.
|Unit system||British imperial/US customary|
|Symbol||mi. or mi or (rarely) m|
|1 mi. or mi in ...||... is equal to ...|
|SI units||1609.344 m|
|US survey mile||0.999998 survey mile|
|nautical units||0.86898 nmi|
With qualifiers, mile is also used to describe or translate a wide range of units derived from or roughly equivalent to the Roman mile, such as the nautical mile (now 1.852 km exactly), the Italian mile (roughly 1.852 km), and the Chinese mile (now 500 m exactly). The Romans divided their mile into 5,000 Roman feet but the greater importance of furlongs in Elizabethan-era England meant that the statute mile was made equivalent to 8 furlongs or 5,280 feet in 1593. This form of the mile then spread across the British Empire, some of which continue to employ the mile. The US Geological Survey now employs the metre for official purposes, but legacy data from its 1927 geodetic datum has meant that a separate US survey mile (6336/3937 km) continues to see some use, although it will be officially phased out in 2022. While most countries replaced the mile with the kilometre when switching to the International System of Units (SI), the international mile continues to be used in some countries, such as Liberia, the United Kingdom, the United States, and a number of countries with fewer than one million inhabitants, most of which are UK or US territories or have close historical ties with the UK or US.