Convert Chain to Fathom
Convert chains to fathoms instantly. 1 chain = 11 fathom — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Fathom to Chain converter for the reverse conversion.
Units explained
Chain
A chain is an Imperial unit of length equal to 66 feet (20.1168 m), or exactly 4 rods or 100 links. It is the central unit in the Gunter chain-based land-survey system.
Defined by Edmund Gunter in 1620 specifically to make land-area arithmetic easy: 10 square chains = 1 acre exactly. The 66-foot length and 100-link subdivision were chosen so chain measurements could be added decimally.
Chains are the fundamental unit of legacy US public land surveys (the entire US township-and-range system uses chains). Modern survey work generally uses meters or feet, but legacy deeds remain in chains.
Invented by Edmund Gunter in 1620; standardised throughout English and American land survey; became exact via the 1959 International Yard and Pound Agreement.
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.
Chain to Fathom conversion formula
The relationship between chains and fathoms:
To convert chains to fathoms, multiply the value in chains by 11. To reverse, multiply fathoms by 0.0909090909.
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 Chain converter for the reverse direction.
Step-by-step: convert chains to fathoms
- Write down the value in chains (ch).
- Multiply that value by the factor 11.
- The product is the equivalent value in fathoms (ftm).
- To reverse, multiply the fathom value by 0.0909090909.
Worked examples
Example 1 — Convert 1 ch to ftm:
1 × 11 = 11 ftm
Example 2 — Convert 100 ch to ftm:
100 × 11 = 1100 ftm
Chain to Fathom conversion table
Standard reference values for converting chains to fathoms:
| Chain [ch] | Fathom [ftm] |
|---|---|
| 0.01 | 0.11 |
| 0.1 | 1.1 |
| 1 | 11 |
| 2 | 22 |
| 3 | 33 |
| 4 | 44 |
| 5 | 55 |
| 10 | 110 |
| 20 | 220 |
| 30 | 330 |
| 40 | 440 |
| 50 | 550 |
| 100 | 1100 |
| 500 | 5500 |
| 1000 | 11000 |
Frequently asked questions
How many fathoms is 1 chain?
How do I convert chains to fathoms?
How do I convert fathoms back to chains?
How many fathoms is 100 chains?
Popular length unit conversions
Convert Chain to other length units
Show all Chain conversions
Metric / SI (4 units)
Imperial / US Customary (26 units)
Sources & references
Conversion factor (1 ch = 11 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.