Convert Foot to Fathom
Convert feet to fathoms instantly. 1 foot = 0.1666666667 fathom — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Fathom to Foot converter for the reverse conversion.
Units explained
Foot
A foot is an Imperial and US customary unit of length equal to 12 inches or exactly 0.3048 meters. It is the most commonly used unit of length in everyday measurement in the United States.
The foot's origin is literally the length of a human foot, used as a measurement standard since antiquity. The English foot was standardized at various points in history; the modern international foot (0.3048 m exactly) was fixed by the 1959 International Yard and Pound Agreement.
Feet are used in the US for body height, building dimensions, room sizes, road sign clearances, aviation altitude (feet above sea level), and most everyday distance estimation. The UK uses feet informally for height despite officially being metric.
Used since antiquity; standardized to 0.3048 m exactly by the International Yard and Pound Agreement of 1959. Aviation worldwide uses feet for altitude despite metric adoption elsewhere.
Fathom
A fathom is an Imperial unit of length equal to 6 feet or exactly 1.8288 meters. It is used almost exclusively for measuring water depth in maritime contexts.
The fathom derives from the Old English word fæthm, meaning "the embracing arms" — the distance between the fingertips of a person's outstretched arms. Standardized at 6 feet in English maritime tradition.
Fathoms are used in nautical depth charts, scuba diving, oceanography, and maritime literature. Despite metrication efforts, fathoms remain common in English-language nautical charts and recreational diving.
Old English origin (predating 1066); standardized at 6 feet by English maritime tradition; fixed at 1.8288 m exactly via the 1959 International Yard and Pound Agreement.
Foot to Fathom conversion formula
The relationship between feet and fathoms:
To convert feet to fathoms, multiply the value in feet by 0.1666666667. To reverse, multiply fathoms by 6.
How to use this converter
Type a value into the calculator. The result in fathoms updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Fathom to Foot converter for the reverse direction.
Step-by-step: convert feet to fathoms
- Write down the value in feet (ft).
- Multiply that value by the factor 0.1666666667.
- The product is the equivalent value in fathoms (ftm).
- To reverse, multiply the fathom value by 6.
Worked examples
Example 1 — Convert 1 ft to ftm:
1 × 0.1666666667 = 0.1666666667 ftm
Example 2 — Convert 100 ft to ftm:
100 × 0.1666666667 = 16.6666666667 ftm
Real-world example — Adult height conversion
A 1.8-foot-tall person measures a value in fathoms that converts the height to the unit favoured by American forms, schools, or driver's licences. This is daily routine for anyone living between metric and imperial systems.
1.8 ft × 0.1666666667 = 0.3 ftm
Real-world example — Fabric purchase length
Two feet of fabric equals a value in fathoms essential for tailors and textile buyers sourcing material from international suppliers that quote in different units.
2 ft × 0.1666666667 = 0.3333333333 ftm
Real-world example — Maritime depth conversion
A 10-foot sounding depth converts cleanly into fathoms. Recreational divers and sailors translate between the two units whenever they read legacy charts against modern depth-sounder displays.
10 ft × 0.1666666667 = 1.6666666667 ftm
Foot to Fathom conversion table
Standard reference values for converting feet to fathoms:
| Foot [ft] | Fathom [ftm] |
|---|---|
| 0.01 | 0.0016666667 |
| 0.1 | 0.0166666667 |
| 1 | 0.1666666667 |
| 2 | 0.3333333333 |
| 3 | 0.5 |
| 4 | 0.6666666667 |
| 5 | 0.8333333333 |
| 10 | 1.6666666667 |
| 20 | 3.3333333333 |
| 30 | 5 |
| 40 | 6.6666666667 |
| 50 | 8.3333333333 |
| 100 | 16.6666666667 |
| 500 | 83.3333333333 |
| 1000 | 166.6666666667 |
Frequently asked questions
How many fathoms is 1 foot?
How do I convert feet to fathoms?
How do I convert fathoms back to feet?
How many fathoms is 100 feet?
Popular length unit conversions
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Metric / SI (18 units)
Imperial / US Customary (26 units)
Nautical (1 units)
Astronomical (9 units)
Atomic / Physics (6 units)
Typographic (3 units)
Sources & references
Conversion factor (1 ft = 0.1666666667 ftm) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.