Feet to Fathoms (ft to ftm)

1 foot equals 0.1666666667 fathoms (rounded).

1 foot = 0.1666666667 fathoms

How to convert feet to fathoms

To convert feet to fathoms, multiply the number of feet by 0.1666666667. The factor is rounded to 10 significant digits. To go the other way, multiply fathoms by 6.

fathoms = feet × 0.1666666667

Example: 10 feet = 1.666666667 fathoms.

About these units

Foot (ft)

US & ImperialCurrent unit

12 inches. Defined as exactly 0.3048 meters. Still the standard unit for height, altitude in aviation and room dimensions in the US and UK.

Human anatomy supplied the idea: an adult foot is roughly 15 percent of body height. Ancient cultures turned that into standards, but not the same one. The Greek pous was about 302 mm, the standard Roman pes about 295.7 mm, and a Harappan foot of about 335 mm has been reported from the Indus Valley. Historically, a foot fell somewhere between about 250 and 335 mm. Charlemagne tried to standardize units around 790 with little lasting success, and in 1593 English law fixed the statute mile at 5,280 feet.

The modern foot dates from the 1959 International Yard and Pound Agreement, which defined the yard as exactly 0.9144 meter and so the foot as exactly 0.3048 meter; the UK adopted it on 1 January 1964. The US survey foot, defined in 1893 as 1200/3937 meter, was deprecated on 31 December 2022. Feet remain in everyday use for height and rooms in the US, and ISO shipping containers are defined in them. Aviation altitudes use them too: flight level 330 means 33,000 feet.

1 foot = 0.3048 meters (exactly).

Sources: Wikipedia: Foot (unit); Wikipedia: Mile; NIST Guide to the SI, Appendix B.8: conversion factors

Fathom (ftm)

NauticalTraditional unit (still used in some regions)

6 feet (1.8288 m), traditionally the span of a man's outstretched arms. Still used for water depth on nautical charts in some countries.

Old English fæðm meant a pair of outstretched arms, and the word gave English its fathom. That is the origin of the measure: the span between the fingertips of a man with his arms spread wide, roughly the height of a person. Because bodies differ, the fathom was not fixed for centuries. Merchant ships are recorded as using about five and a half feet, and fishing boats five or seven, until the length was settled at six feet in the nineteenth century.

Sailors counted in fathoms because a hand sounding line carried marks at fathom intervals, so the depth could be read off when the weight touched bottom. Water shallower than 100 fathoms was said to be in soundings. Anchor chain and fishing line were also sold and counted in fathoms. The figure used here is exactly six feet, or 1.8288 m, which makes two yards one fathom. Most charts today show metres, though some national charts still print fathoms.

1 fathom = 1.8288 meters (exactly).

Sources: Wikipedia: Fathom; NIST SP 811, Appendix B.8 (length conversion factors)

Related conversions

See all length units.