A cable length or length of cable is a nautical unit of measure equal to one tenth of a nautical mile or approximately 100 fathoms. Due to anachronisms and varying techniques of measurement, a cable length can be anywhere from 169 to 220 metres, depending on the standard used. The unit is named after the length of a ship's anchor cable in the Age of Sail.
The definition varies:
- International: 185.2 m, equivalent to 1⁄10 nautical mile
- Imperial (Admiralty): 185.32 m, or 1⁄10 nautical mile, about 101 fathoms
- The traditional British fathom varied from 5+1⁄2 to 7 feet (1.7 to 2.1 metres) in the Merchant Navy, making the "historical" cable 169 m to 215.5 m.
- U.S. customary (US Navy): 219.5 metres, 120 fathoms (720 feet)
- Fenna, Donald (2002), "cable, cable length, cable's length", A Dictionary of Weights, Measures, and Units, Oxford: Oxford University Press, p. 35, ISBN 0-19-860522-6, OCLC 62608533, retrieved 12 January 2017. Also "fathom", from the same work (pp. 88–89, retrieved 12 January 2017).
- Navy Slang: Cable – Curry, Royal Navy, 2007, archived from the original on 2008-07-07, retrieved 1 February 2011.