Convert Inch to Fathom
Convert inches to fathoms instantly. 1 inch = 0.0138888889 fathom — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Fathom to Inch converter for the reverse conversion.
Units explained
Inch
An inch is an Imperial and US customary unit of length defined since 1959 as exactly 25.4 millimeters (0.0254 meters). It is still the standard small unit of length in the United States, the United Kingdom (informally), and a few other countries.
The inch derives from the Roman uncia (one-twelfth of a foot) and survived through Anglo-Saxon and medieval English measurement systems. Various definitions persisted regionally until the 1959 International Yard and Pound Agreement standardized the inch globally as exactly 25.4 mm.
Inches are used in the US and UK for body height, screen sizes (TVs, monitors, phones), tire sizes, plumbing, lumber, paper sizes (US Letter is 8.5 × 11 in), and most consumer product specifications in the United States.
Anglo-Saxon origin (predating 1066); standardized to 25.4 mm exactly by the International Yard and Pound Agreement of 1959, signed by the US, UK, Canada, Australia, New Zealand, and South Africa.
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.
Inch to Fathom conversion formula
The relationship between inches and fathoms:
To convert inches to fathoms, multiply the value in inches by 0.0138888889. To reverse, multiply fathoms by 72.
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 Inch converter for the reverse direction.
Step-by-step: convert inches to fathoms
- Write down the value in inches (in).
- Multiply that value by the factor 0.0138888889.
- The product is the equivalent value in fathoms (ftm).
- To reverse, multiply the fathom value by 72.
Worked examples
Example 1 — Convert 1 in to ftm:
1 × 0.0138888889 = 0.0138888889 ftm
Example 2 — Convert 100 in to ftm:
100 × 0.0138888889 = 1.3888888889 ftm
Real-world example — Body height conversion
You enter your height as 180 inches into an international job or visa application. The form then asks for the same value in fathoms — converting between these adjacent units is one of the most-used length conversions globally.
180 in × 0.0138888889 = 2.5 ftm
Real-world example — Furniture and large objects
A 72-inch piece of furniture converts to a value in fathoms that's easier to mentally compare with room dimensions. This is the typical workflow when shopping internationally and product specs use a different unit than your room measurements.
72 in × 0.0138888889 = 1 ftm
Real-world example — Children's height milestones
A 150-inch-tall child measures a value in fathoms that's commonly used for theme-park ride height requirements when travelling between countries that use different measurement units.
150 in × 0.0138888889 = 2.0833333333 ftm
Inch to Fathom conversion table
Standard reference values for converting inches to fathoms:
| Inch [in] | Fathom [ftm] |
|---|---|
| 0.01 | 0.0001388889 |
| 0.1 | 0.0013888889 |
| 1 | 0.0138888889 |
| 2 | 0.0277777778 |
| 3 | 0.0416666667 |
| 4 | 0.0555555556 |
| 5 | 0.0694444444 |
| 10 | 0.1388888889 |
| 20 | 0.2777777778 |
| 30 | 0.4166666667 |
| 40 | 0.5555555556 |
| 50 | 0.6944444444 |
| 100 | 1.3888888889 |
| 500 | 6.9444444444 |
| 1000 | 13.8888888889 |
Frequently asked questions
How many fathoms is 1 inch?
How do I convert inches to fathoms?
How do I convert fathoms back to inches?
How many fathoms is 100 inches?
Popular length unit conversions
Convert Inch to other length units
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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 in = 0.0138888889 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.