Nautical mile

This article is about distance measurement at sea. For distance measurement on land, see mile. For the U.S. unit based on the Equator, see geographical mile.
Nautical mile
Historical definition – 1 nautical mile
General information
Unit oflength
SymbolM, NM,[a] or nmi
Conversions
1 M, NM,[a] or nmi in ...... is equal to ...
   metre   1,852[1]
   foot   ≈ 6,076.11549
   statute mile   ≈ 1.15078
   cable   10

A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters.[2][3][4] Historically, it was defined as the meridian arc length corresponding to one minute (⁠1/60⁠ of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees). Today the international nautical mile is defined as 1,852 metres (about 6,076 ft; 1.151 mi).[5] The derived unit of speed is the knot, one nautical mile per hour.


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  1. ^ Göbel, E.; Mills, I.M.; Wallard, Andrew, eds. (2006). The International System of Units (SI) (PDF) (8th ed.). Paris: Bureau International des Poids et Mesures. p. 127. ISBN 92-822-2213-6. Archived from the original (PDF) on 2017-08-14. Retrieved 2017-06-20.
  2. ^ Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 200. ISBN 9780850451634.
  3. ^ "mile | unit of measurement". Encyclopædia Britannica. Archived from the original on 2022-10-25. Retrieved 2016-06-10.
  4. ^ "UNITED NATIONS CONVENTION ON THE LAW OF THE SEA". www.un.org. Archived from the original on 2017-12-18. Retrieved 2016-06-10.
  5. ^ Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 200. ISBN 9780850451634.