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Multiple conversions
To convert from Fathom (fathom) to Nanometer (nm), use the following formula:
Nanometer (nm)
= 6 × 0.3048 × 109× Fathom (fathom)
= 1828800000× Fathom (fathom)
With 0.3048 is the ratio between the base units Meter (m) and Foot (ft).
To convert from Fathom (fathom) to Micrometer (μm), use the following formula:
Micrometer (μm)
= 6 × 0.3048 × 106× Fathom (fathom)
= 1828800× Fathom (fathom)
With 0.3048 is the ratio between the base units Meter (m) and Foot (ft).
To convert from Fathom (fathom) to Millimeter (mm), use the following formula:
Millimeter (mm)
= 6 × 0.3048 × 1000× Fathom (fathom)
= 1828.8× Fathom (fathom)
With 0.3048 is the ratio between the base units Meter (m) and Foot (ft).
To convert from Fathom (fathom) to Centimeter (cm), use the following formula:
Centimeter (cm)
= 6 × 0.3048 × 100× Fathom (fathom)
= 182.88× Fathom (fathom)
With 0.3048 is the ratio between the base units Meter (m) and Foot (ft).
To convert from Fathom (fathom) to Decimeter (dm), use the following formula:
Decimeter (dm)
= 6 × 0.3048 × 10× Fathom (fathom)
= 18.288× Fathom (fathom)
With 0.3048 is the ratio between the base units Meter (m) and Foot (ft).
To convert a depth or length from fathoms to meters (m), multiply by 1.8288.
A fathom is exactly six feet, and the foot is defined as exactly 0.3048 m, so the factor 6 × 0.3048 = 1.8288 is exact. A serviceable mental shortcut: fathoms × 2, minus 10%.
An older nautical chart marks an anchorage at 15 fathoms, and the vessel's echo sounder reads meters:
The reverse divides: a 50 m depth contour sits at 27.34 fathoms.
| fathoms | m |
|---|---|
| 1 | 1.83 |
| 2 | 3.66 |
| 5 | 9.14 |
| 10 | 18.29 |
| 15 | 27.43 |
| 100 | 182.88 |
The fathom descends from the span of a sailor's outstretched arms — the length of sounding line hauled in per pull — and it remains the signature unit of marine depth. Modern official charts from most hydrographic offices are metric, but fathoms survive in three places that keep this conversion alive: older US and British charts still in circulation (US chart depths also appear in feet), fishing practice in English-speaking fleets, where net depths and ground descriptions are habitually given in fathoms, and literature — Mark Twain took his pen name from the leadsman's call for two fathoms of safe water. Chart work is where precision matters: a chart sounding in fathoms misread as meters understates depth by nearly half, which is at least conservative, but the reverse error — treating meters as fathoms — nearly doubles the apparent water under the keel. Checking the chart's title block for its depth unit before converting is standard bridge discipline, and the ×1.8288 factor handles the rest exactly.
To convert from Fathom (fathom) to Kilometer (km), use the following formula:
Kilometer (km)
= 6 × 0.3048 × 11000× Fathom (fathom)
= 0.0018288× Fathom (fathom)
With 0.3048 is the ratio between the base units Meter (m) and Foot (ft).
To convert from Fathom (fathom) to Mil (mil), use the following formula:
Mil (mil)
= 6 × 12000× Fathom (fathom)
= 72000× Fathom (fathom)
To convert from Fathom (fathom) to Inch (in), use the following formula:
Inch (in)
= 6 × 12× Fathom (fathom)
= 72× Fathom (fathom)
To convert from Fathom (fathom) to Yard (yd), use the following formula:
Yard (yd)
= 6 × 13× Fathom (fathom)
= 2× Fathom (fathom)
To convert from Fathom (fathom) to US Survey Foot (ft-us), use the following formula:
US Survey Foot (ft-us)
= 6 × 11.000002× Fathom (fathom)
= 5.999988000023999952× Fathom (fathom)
To convert from Fathom (fathom) to Foot (ft), use the following formula:
Foot (ft)
= 6× Fathom (fathom)
To convert from Fathom (fathom) to Mile (mi), use the following formula:
Mile (mi)
= 6 × 15280× Fathom (fathom)
= 0.0011363636363636363636× Fathom (fathom)
To convert from Fathom (fathom) to Nautical Mile (nMi), use the following formula:
Nautical Mile (nMi)
= 6 × 16076.12× Fathom (fathom)
= 0.00098747226848712665319× Fathom (fathom)
A fathom is a unit of length in the imperial system of measurement.
It is most famously used for measuring the depth of water.
A fathom is equal to exactly 6 feet (or 1.8288 meters). The plural form is fathoms.
The word "fathom" originates from the Old English word "fæthm," which means "outstretched arms" or "a pair of embracing arms."
Historically, a fathom was defined as the distance from the middle fingertip of one hand to the middle fingertip of the other when a person's arms are fully extended.
This made it a convenient and readily available unit of measurement for sailors and workers.
The fathom is best known for its use in a nautical context to measure water depth.
Mariners would drop a weighted line, called a sounding line, into the water and count the number of "arm spans" it took to reach the bottom.
This measurement was crucial for safe navigation, anchoring, and creating nautical charts to map the seabed.
While modern technology and the metric system have replaced the fathom in official hydrographic surveys, its influence persists.
The term is still used informally in commercial fishing and can be found on many older nautical charts.
Figuratively, the verb "to fathom"—meaning to understand something deeply—is a direct link to the original act of measuring depth and getting to the bottom of things.