Miles
Abbreviation/Symbol:
mile
mi
Unit of:
Worldwide use:
Road distances are still given in miles in the United States and the United Kingdom, along with speed limits in miles per hour.
Most other countries use kilometers. Canada and Australia changed their road signs over in the 1970s.
The marathon shows both sets of units: 42.195km is 26 miles 385 yards.
The mile is exactly 1.609344 kilometers, so 100 miles is about 161 kilometers.
Definition:
The mile is a unit of length commonly used in the United States and the United Kingdom. It is defined as 5,280 feet or 1,760 yards.
The mile is still the unit for road distances in the US and the UK, and UK road signs show miles even though most other measurements there are now metric. Speed limits in both countries are in miles per hour.
The mile is a convenient unit for measuring long distances, as it provides a reasonable balance between being too small to be practical and too large to be easily visualized. It is often used in combination with other units, such as minutes or hours, to measure speed or pace. For example, a car traveling at 60 miles per hour would cover a distance of 60 miles in one hour.
Origin:
The mile comes from ancient Rome, where the mille passus was 'a thousand paces' – a pace being two steps, so about 1,480 meters in all. The Romans marked it along their roads with milestones.
The English mile was fixed by Parliament in 1593 at eight furlongs, which is 1,760 yards or 5,280 feet. That made it a little longer than the Roman mile it descended from.
The mile spread with the British Empire, and most countries have since replaced it with the kilometer. The US and the UK still use it for road distances, and for running races such as the marathon (26.2 miles).
Common references:
3 miles - distance travelled with a leisurely walk in an hour
4 miles - distance travelled with a brisk walk in an hour
24,901 miles = circumference of the earth
238,855 miles = distance to the moon
93,000,000 miles = distance to the sun
Usage context:
Road distances in the United States and the United Kingdom are in miles, so road signs, speed limits and car odometers use them. Aviation and shipping use nautical miles instead.
Runners and cyclists in the US and UK log their training in miles, but the marathon is defined in kilometers: 42.195, or 26 miles 385 yards.
Nearly everywhere else uses kilometers, and the quick conversion is to multiply miles by 1.6 – 60 miles is about 96 kilometers. Exactly, a mile is 1.609344 kilometers, which makes it 96.56 kilometers.
Statute miles:
A statute mile is 5,280 feet, exactly 1,609.344 meters. It is the ordinary land mile, used for roads and race tracks in the US and UK.
The statute mile takes its name from an Act of Parliament in 1593 that fixed it at eight furlongs. It is still the unit on UK and US road signs, and a marathon is 26 miles 385 yards (42.195km).
US Survey Mile:
The US survey mile is 5,280 US survey feet, or 1,609.3472 meters. It is not the statute mile, which today means the international mile of 1,609.344 meters – the survey mile is longer by about 1/8 inch.
The US survey mile is based on the survey foot (1200/3937 meters), so it is 1,609.3472 meters – 3.2mm longer than the international mile. US land surveys used it until the survey foot was retired on 1 January 2023.
Roman Mile:
The Roman mile was the mille passus, Latin for a thousand paces. A pace was two steps, about 5 Roman feet, so the mile was 5,000 Roman feet.
Roman roads had a milestone at every mile (the milliarium), so the mille passus became the standard way to quote a distance along them. A Roman mile was about 1,480 meters, roughly 8% shorter than the modern mile.
Although the Roman mile is no longer in use today, its influence can still be seen in modern measurements. The mile, as used in the United States and the United Kingdom, is derived from the Roman mile. It is approximately 1,609 meters long, which is slightly longer than the Roman mile. This shows the lasting impact of the Roman measurement system and its contribution to the development of modern units of measurement.
Nautical mile:
A nautical mile is exactly 1,852 meters, or about 1.1508 statute miles, (1.852 kilometers), and it started out as one minute of latitude.
That origin means 60 nautical miles make one degree of latitude, so a navigator can read distances straight off the side of a chart. Ships and aircraft both use it, with speed in knots – one knot being one nautical mile per hour.
More information on the Nautical Mile can be found here.
Italian Mile:
The Italian mile, or miglio, descends from the Roman mille passus, a thousand paces.
Italy used the miglio for road distances until the metric system replaced it in the 19th century. Before unification in 1861 its length differed from one Italian state to the next, so there was never a single value for it.
Miglio is still the Italian word for any mile, nautical ones included (miglio nautico).
Chinese Mile:
The li (里) is the traditional Chinese unit of distance, now fixed at 500 meters or about 0.31 miles. Its length drifted a good deal between dynasties, so a li in an old text may not match that.
The li is still used in everyday speech in China, and 'a thousand li' (千里) is the phrase for a very long way – 500km at the modern value. It was never used to find acupuncture points, though – those are located in cun, a finger's width.