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Fathom (fath) - Unit Information & Conversion

Symbol:fath
Plural:fathoms
Category:Length

What is a Fathom?

Definition

The Fathom (symbol fath) is a unit of length in the imperial and U.S. customary systems of measurement, defined as exactly 6 feet (ft). This is equivalent to 2 yards or 1.8288 meters (m). It is almost exclusively used in maritime contexts for measuring the depth of water.

History

The word "fathom" originates from the Old English word fæthm, meaning "a pair of outstretched arms" or "embrace". Historically, the length was derived from the distance between the fingertips of a man's outstretched arms, a practical method for sailors measuring the length of a sounding line (a rope with a weight used to measure water depth) as they hauled it in. This naturally variable measure was eventually standardized to precisely 6 feet. For centuries, it was the primary unit for depth soundings on nautical charts and in maritime operations in English-speaking countries and beyond. While its official use has declined with metrication, it remains a significant unit in nautical tradition.

Common Uses

The fathom's use is strongly tied to the sea:

  • Hydrography & Navigation: Measuring water depth (soundings) on nautical charts. Many charts, particularly older ones or those used in the US and UK, still use fathoms. Contour lines showing seabed depth are often called "fathom lines".
  • Nautical Terminology: Used historically to measure the length of ropes and anchor cables (e.g., a "cable length" was often defined as 100 or 120 fathoms).
  • Commercial Fishing: Sometimes used by fishermen to describe the length of nets or fishing lines, or the depth at which they are fishing.
  • Literature & Figurative Language: Frequently appears in maritime literature (e.g., "full fathom five" from Shakespeare's The Tempest). Metaphorically, "to fathom" means to comprehend or get to the bottom of something complex.
  • Historical Land Measurement: Very occasionally used in historical land surveying or mining contexts, but this was rare compared to its maritime use.

Unit FAQs

How many feet are in a fathom?

There are exactly 6 feet (ft) in 1 fathom.

How many meters are in a fathom?

One fathom is equal to exactly 1.8288 meters (m).

Is the fathom an SI unit?

No, the fathom is not an SI unit. It is part of the imperial and U.S. customary systems. The corresponding SI unit for length is the meter (m).

Is the fathom still commonly used today?

Its usage has decreased significantly due to the widespread adoption of the metric system in international shipping and hydrography. However, it remains common on nautical charts produced by countries like the United States and the United Kingdom, and it persists in recreational boating, commercial fishing communities, maritime tradition, and literature. Modern international charts increasingly use meters for depth soundings.

Where does the word 'fathom' come from?

The word originates from the Old English fæthm, which referred to the span of a person's outstretched arms. This distance was the practical basis for the original measurement used by sailors.

Fathom Conversion Formulas

To Meter:

1 fath = 1.8288 m
Example: 5 fathoms = 9.144 meters

To Kilometer:

1 fath = 0.001829 km
Example: 5 fathoms = 0.009144 kilometers

To Hectometer:

1 fath = 0.018288 hm
Example: 5 fathoms = 0.09144 hectometers

To Decimeter:

1 fath = 18.288 dm
Example: 5 fathoms = 91.44 decimeters

To Centimeter:

1 fath = 182.88 cm
Example: 5 fathoms = 914.4 centimeters

To Millimeter:

1 fath = 1828.8 mm
Example: 5 fathoms = 9144 millimeters

To Inch:

1 fath = 72 in
Example: 5 fathoms = 360 inches

To Foot:

1 fath = 6 ft
Example: 5 fathoms = 30 feet

To Yard:

1 fath = 2 yd
Example: 5 fathoms = 10 yards

To Mile:

1 fath = 0.001136 mi
Example: 5 fathoms = 0.005682 miles

To Nautical Mile:

1 fath = 0.000987 NM
Example: 5 fathoms = 0.004937 nautical miles

To Micrometer:

1 fath = 1828800 μm
Example: 5 fathoms = 9144000 micrometers

To Nanometer:

1 fath = 1828800000 nm
Example: 5 fathoms = 9144000000 nanometers

To Light Year:

1 fath = 1.9330e-16 ly
Example: 5 fathoms = 9.6649e-16 light years

To Astronomical Unit:

1 fath = 1.2225e-11 AU
Example: 5 fathoms = 6.1123e-11 astronomical units

To Parsec:

1 fath = 5.9267e-17 pc
Example: 5 fathoms = 2.9633e-16 parsecs

To Angstrom:

1 fath = 18288000000 Å
Example: 5 fathoms = 91440000000 angstroms

To Point (Typography):

1 fath = 5183.996734 pt
Example: 5 fathoms = 25919.983672 points

To Mil/Thou:

1 fath = 72000 mil
Example: 5 fathoms = 360000 mils

To Furlong:

1 fath = 0.009091 fur
Example: 5 fathoms = 0.045455 furlongs

To Link (Gunter's):

1 fath = 9.090909 li
Example: 5 fathoms = 45.454545 links

To Pace:

1 fath = 2.4 pace
Example: 5 fathoms = 12 paces

To Span:

1 fath = 8 span
Example: 5 fathoms = 40 spans

To Digit:

1 fath = 96 digit
Example: 5 fathoms = 480 digits

To Cable Length:

1 fath = 0.009875 cb
Example: 5 fathoms = 0.049374 cable lengths

To Ell:

1 fath = 1.6 ell
Example: 5 fathoms = 8 ells

To Finger:

1 fath = 16 finger
Example: 5 fathoms = 80 fingers

To Roman Mile:

1 fath = 0.001236 m.p.
Example: 5 fathoms = 0.006178 Roman miles

To Stadion:

1 fath = 0.009885 stadion
Example: 5 fathoms = 0.049427 stadia

To Chi (Chinese):

1 fath = 5.486949 chi
Example: 5 fathoms = 27.434743 chi

To Shaku (Japanese):

1 fath = 6.035644 shaku
Example: 5 fathoms = 30.178218 shaku

To Li (Chinese):

1 fath = 0.003658 li
Example: 5 fathoms = 0.018288 li

To Toise:

1 fath = 0.938327 toise
Example: 5 fathoms = 4.691637 toise

To Bolt:

1 fath = 0.06 bolt
Example: 5 fathoms = 0.3 bolts

To Rope:

1 fath = 0.3 rope
Example: 5 fathoms = 1.5 ropes

To Smoot:

1 fath = 1.074627 smoot
Example: 5 fathoms = 5.373134 smoots

To Sajene:

1 fath = 0.857143 sajene
Example: 5 fathoms = 4.285714 sajenes

To Ken:

1 fath = 1.005941 ken
Example: 5 fathoms = 5.029703 ken

To Wa:

1 fath = 0.9144 wa
Example: 5 fathoms = 4.572 wa

To Vara:

1 fath = 2.181818 vara
Example: 5 fathoms = 10.909091 varas

To Aln:

1 fath = 3.078788 aln
Example: 5 fathoms = 15.393939 alnar

To Cubit (Royal/Egyptian):

1 fath = 3.49675 cubit
Example: 5 fathoms = 17.483748 cubits

To Versta:

1 fath = 0.001714 versta
Example: 5 fathoms = 0.008571 versts

To Arpent:

1 fath = 0.031277 arpent
Example: 5 fathoms = 0.156385 arpents

To Ri (Japanese):

1 fath = 0.000466 ri
Example: 5 fathoms = 0.002328 ri

To Klafter:

1 fath = 0.964303 klafter
Example: 5 fathoms = 4.821513 klafter

To Yojana:

1 fath = 0.000135 yojana
Example: 5 fathoms = 0.000677 yojanas

To Skein:

1 fath = 0.016667 skein
Example: 5 fathoms = 0.083333 skeins

Convert Fathom

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Fathom Quick Info

fath
Symbol:fath
Category:Length
System:Various
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