Fathoms, feet and meters
Type in any box and the other two update. Results round to 0.001 fathom, 0.01 foot and 0.0001 meter.
A fathom is exactly 6 feet, or 1.8288 meters. To convert fathoms to feet, multiply by 6. To convert feet to fathoms, divide by 6. The fathom is used mainly for the depth of water: NOAA’s traditional paper charts of U.S. waters gave depths in feet or fathoms, and NOAA’s Custom Chart tool can still show depths in fathoms.
Formulas: feet = fathoms × 6 · meters = fathoms × 1.8288 · fathoms = feet ÷ 6
How Deep Is a Fathom?
One fathom is 6 feet, which is 2 yards or 1.8288 meters. These are exact values: the U.S. National Institute of Standards and Technology (NIST) lists the fathom as exactly 6 feet, and the foot as exactly 0.3048 meter. The U.S. fathom used to be tied to the slightly longer U.S. survey foot, but NIST retired the survey foot at the end of 2022, so the U.S. fathom is now exactly 1.8288 meters as well.
So 2 fathoms of water are 12 feet deep, 10 fathoms are 60 feet and 100 fathoms are 600 feet. The converter above works in all three directions: type a depth in fathoms, feet or meters and the other two boxes update. To work out how much anchor rode to let out in a given depth, use the Anchor Scope Calculator.
Fathoms to Feet Conversion Chart
Depths from 1 to 10 fathoms:
| Fathoms | Feet | Meters |
|---|---|---|
| 1 | 6 | 1.8288 |
| 2 | 12 | 3.6576 |
| 3 | 18 | 5.4864 |
| 4 | 24 | 7.3152 |
| 5 | 30 | 9.144 |
| 6 | 36 | 10.9728 |
| 7 | 42 | 12.8016 |
| 8 | 48 | 14.6304 |
| 9 | 54 | 16.4592 |
| 10 | 60 | 18.288 |
Deeper water, from 15 to 200 fathoms:
| Fathoms | Feet | Meters |
|---|---|---|
| 15 | 90 | 27.432 |
| 18 | 108 | 32.9184 |
| 20 | 120 | 36.576 |
| 25 | 150 | 45.72 |
| 30 | 180 | 54.864 |
| 40 | 240 | 73.152 |
| 50 | 300 | 91.44 |
| 70 | 420 | 128.016 |
| 90 | 540 | 164.592 |
| 100 | 600 | 182.88 |
| 120 | 720 | 219.456 |
| 200 | 1,200 | 365.76 |
How Many Fathoms Are in a Foot?
One foot is one-sixth of a fathom, about 0.167 fathom. To convert feet to fathoms, divide the number of feet by 6; to convert meters to fathoms, divide by 1.8288. One meter is about 0.547 fathom, or 3.28 feet.
| Feet | Fathoms | Meters |
|---|---|---|
| 1 | 0.167 | 0.3048 |
| 3 | 0.5 | 0.9144 |
| 5 | 0.833 | 1.524 |
| 6 | 1 | 1.8288 |
| 10 | 1.667 | 3.048 |
| 12 | 2 | 3.6576 |
| 20 | 3.333 | 6.096 |
| 30 | 5 | 9.144 |
| 50 | 8.333 | 15.24 |
| 60 | 10 | 18.288 |
| 100 | 16.667 | 30.48 |
| 300 | 50 | 91.44 |
Fathoms on Nautical Charts
The numbers printed across the water on a nautical chart are soundings, or depths, and every chart states the unit it uses. NOAA’s traditional paper charts of U.S. waters gave depths in feet or in fathoms; in its 2017 National Charting Plan, NOAA noted that all but a handful of its more than 1,000 raster charts showed depths in feet or fathoms. NOAA’s Office of Coast Survey has since retired those paper charts, together with the raster charts made from them: the last paper chart was removed from its catalog and archived on December 5, 2024.
NOAA’s charts are now electronic navigational charts (ENCs). The international ENC standard requires every depth to be stored in meters, so NOAA converted the fathoms and feet of its paper charts into meters when it built its ENCs. For a paper chart, NOAA’s Custom Chart tool builds a printable chart from the latest ENC data and can show the depths in meters, feet or fathoms.
British Admiralty charts from the UK Hydrographic Office switch to meters as they are modernized, except charts of U.S. waters, where fathoms or feet are kept. On a fathoms chart the land is printed gray and the title block gives the depth unit. Depths shallower than 11 fathoms are usually written in fathoms and feet, so a sounding of 3 fathoms 4 feet means 22 feet of water. Our guide How to Read a Nautical Chart covers the rest of a chart, from depth contours to buoys.
Where the Word Fathom Comes From
Fathom comes from the Old English fæthm, meaning “outstretched arms.” As a verb, to fathom means to measure the depth of water, and also to understand something fully.
On Mississippi steamboats, leadsmen sang out the depths they sounded. In Life on the Mississippi (1883), Mark Twain explains that “mark twain” meant two fathoms (12 feet) and “quarter twain” two and a quarter fathoms (13½ feet). Samuel Clemens, a licensed river pilot, made the call his pen name.
More Nautical Unit Converters
For distances, the Nautical Miles to Miles Converter turns nautical miles into statute miles, and the Knots to MPH Converter does the same for boat speed. To measure a route between two ports, use the Sea Distance Calculator, and to work out the time, distance or speed of a passage, use the Speed, Distance and Time Calculator.
Frequently Asked Questions
How deep is a fathom?
A fathom is exactly 6 feet, or 1.8288 meters. Two fathoms are 12 feet, 10 fathoms are 60 feet and 100 fathoms are 600 feet.
How long is a fathom?
A fathom is exactly 6 feet long, which is 2 yards or 1.8288 meters.
How many fathoms are in a foot?
One foot is one-sixth of a fathom, about 0.167 fathom. To convert feet to fathoms, divide the number of feet by 6: 30 feet is 5 fathoms.
How do you convert fathoms to meters?
Multiply the number of fathoms by 1.8288. For example, 10 fathoms is 18.288 meters and 50 fathoms is 91.44 meters.
How many fathoms are in a mile?
A statute mile of 5,280 feet is 880 fathoms. A nautical mile of 1,852 meters is about 1,012.7 fathoms.
Do nautical charts still use fathoms?
Fewer than before. NOAA finished retiring its traditional paper charts of U.S. waters, which gave depths in feet or fathoms, in December 2024. Its electronic charts store depths in meters, but its Custom Chart tool can print depths in meters, feet or fathoms. Admiralty charts switch to meters as they are modernized, except charts of U.S. waters.
What does “mark twain” mean?
“Mark twain” was the call a Mississippi riverboat leadsman used for a depth of two fathoms, or 12 feet. Samuel Clemens, a licensed river pilot, took it as his pen name, Mark Twain.