A mile is a unit of length, usually used to measure distance, in a number of different systems, including Imperial units, United States customary units and Norwegian/Swedish mil. Its size can vary from system to system, but in each is between one and fifteen kilometers. In contemporary English contexts, mile most commonly refers to the international mile of 5,280 feet, 1,760 yards, or exactly 1,609.344 meters. However it can also refer to either of the following for specific uses:
- the U.S. survey mile (also known as U.S. statute mile) of 5,280 survey feet which is slightly longer at approximately 1,609.347219 meters (1 international mile is exactly 0.999998 survey mile).[1][2]
- the international nautical mile of 1,852 meters (about 6,076 feet).[3]
There have been several abbreviations for mile (with and without trailing period): mi, ml, m, M. In the United States, the National Institute of Standards and Technology now uses and recommends mi[4] but in everyday usage (at least in the United States and in the United Kingdom) usages such as miles per hour and miles per gallon are almost always abbreviated as mph or mpg (rather than mi/h or mi/gal).
The formula "multiply by 8 and divide by 5" to convert international miles to kilometers gives a conversion of 1.6, accurate to 0.6%, which is a useful approximation.
Historical definitions[]
The unit of distance mille passus (literally "a thousand paces" in Latin, with one pace being equal to two steps) was first used by the Romans and denoted a distance of 1,000 paces or 5,000 Roman feet, and corresponded to about 1,480 meters, or 1,618 modern yards. This unit is now known as the Roman mile.[5]
The current definition of a mile as 5,280 feet (as opposed to 5,000) dates to the 13th century, and was confirmed by statute in the reign of Queen Elizabeth I;[6] However, various English-speaking countries maintained independent length standards for the yard, which differed by small but measurable amounts, and thus led to miles of slightly different lengths. This was resolved in 1959 with the definition of the current international mile by Australia, Canada, New Zealand, South Africa, the United Kingdom, and the United States.[7]
See also[]
- Anthropic units
- Imperial units
- League
- Roman mile
- Wikipedia:Square mile
- Systems of measurement
- U.S. customary units
- Glossary Index
- Units
References[]
- ↑ A. V. Astin & H. Arnold Karo, (1959) Using values in this document, international yard divided by former U.S. yard is (9144×3937)/(3600×10000) = 499999/500000 = 0.999998 exactly.
- ↑ Tina Butcher et al. ed. (2007), Appendix C, p. C-13, footnote 11.
- ↑ Section 4.1 Table 8 in the International System of Units 8th ed. (2006) by the Bureau International des Poids et Mesures.
- ↑ Tina Butcher et al. ed. (2007) Appendix C, p. C-13.
- ↑ Smith, 762
- ↑ Klein (1974, corrected 1988), 69.
- ↑ Louis E. Barbrow and Lewis V. Judson, (1976), 16, 17, 20.
Further reading[]
- Astin. V. and H. Arnold Karo. (1959). Refinement of values for the yard and the pound, Washington DC: National Bureau of Standards, republished on National Geodetic Survey web site and the Federal Register (Doc. 59-5442, Filed, June 30, 1959, 8:45 a.m.)
- Barbrow, Louis E. and Lewis V. Judson (1976). Weights and Measures Standards of the United States: a brief history. National Institute of Standards and Technology.
- Butcher, Tina et al. ed. (2007). NIST Handbook 44: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices. Appendix C, p. C-13.
- Klein, Herbert Arthur (1974, corrected 1988). The Science of Measurement: A Historical Survey. New York: Dover. (previously published by Simon & Schuster under the title The World of Measurements: Masterpieces, Mysteries and Muddles of Metrology)
- Maloney, Elbert S. (1978). Dutton's Navigation and Piloting. 13th Ed. Annapolis: Naval Institute Press.
- Rowlet, Russ (2005). How Many? A Dictionary of Units of Measurement. Faculty member's web page at University of North Carolina at Chapel Hill. Accessed 2007-11-10.
- Smith, William (1875). Dictionary of Greek and Roman Antiquities. London: John Murray, 762.