# Fathoms to Chains (ftm to ch)

Source: https://www.unitconvertercalculator.com/length/fathoms-to-chains/

**1 ftm = 0.090909090909091 ch**

One fathom equals exactly 1/11 of a chain, or approximately 0.09091 chains. Conversely, one chain (66 feet) contains exactly 11 fathoms (66/6 = 11). Both units derive from the English foot-based measurement system, but the fathom measures depth at sea while the chain measures distance on land.

## Formula

Convert Fathoms to Chains

## Conversion Table

| Fathoms (ftm) | Chains (ch) |
|---|---|
| 0.5 ftm | 0.045454545454545 ch |
| 1 ftm | 0.090909090909091 ch |
| 2 ftm | 0.18181818181818 ch |
| 5 ftm | 0.45454545454545 ch |
| 10 ftm | 0.90909090909091 ch |
| 11 ftm | 1 ch |
| 20 ftm | 1.8181818181818 ch |
| 50 ftm | 4.5454545454545 ch |
| 100 ftm | 9.0909090909091 ch |
| 200 ftm | 18.181818181818 ch |
| 500 ftm | 45.454545454545 ch |
| 1000 ftm | 90.909090909091 ch |
| 6000 ftm | 545.45454545455 ch |

## Units

### Fathom (ftm)

Exactly 6 feet (1.8288 m). Traditionally used to measure water depth in nautical contexts. Originally based on the span of outstretched arms.

### Chain (ch)

Exactly 66 feet or 4 rods (20.1168 m). Invented by Edmund Gunter for land surveying. 80 chains make one mile. Still used in US public land surveys.

## Background

Eleven fathoms make one chain. One furlong (10 chains) equals 110 fathoms. One mile (80 chains) equals 880 fathoms. The clean 11:1 ratio exists because both units are exact multiples of the foot: 6 feet per fathom, 66 feet per chain, and 66/6 = 11.

## Good to Know

The fathom and chain both descend from the English foot but diverged into sea and land. Sailors measured rope in fathoms; surveyors measured fields in chains. The 11:1 ratio is a remnant of their shared ancestry in the foot-based system.

## FAQ

### How many chains is 1 fathom?

One fathom equals exactly 1/11 of a chain (approximately 0.09091 chains). Eleven fathoms make exactly one chain.

### How many fathoms are in 1 chain?

One chain contains exactly 11 fathoms. Both are defined in feet: 1 chain = 66 feet, 1 fathom = 6 feet, 66/6 = 11.

### Why is the ratio exactly 11?

Because both units are defined as exact multiples of the foot. The chain is 66 feet, the fathom is 6 feet. 66 divided by 6 equals exactly 11. This clean ratio is a rarity in the imperial system.

## Non-Frequently Asked Questions

### Which is longer, dropping anchor or surveying a field?

A chain (66 feet) is about 3.6 times longer than a fathom (6 feet). But anchor chain measured in fathoms can be hundreds of fathoms long, while a field might be only 10-20 chains. In total length, the anchor chain usually wins. The ocean is bigger than most fields.

### Were chains ever used underwater?

Not surveyor's chains. But anchor chains (measured in nautical fathom-based 'shackles') serve a similar function underwater as surveyor's chains did on land: measuring known lengths of something. Both professions count chain links for a living.

### If I surveyed the ocean floor, would I use fathoms or chains?

Modern ocean floor surveys use meters. Historically, depth used fathoms and horizontal distance used whatever the ship's navigation offered. Nobody dragged a Gunter's chain across the seabed. The barnacles alone would make it impossible.

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## See Also

- [Chains to Fathoms](https://www.unitconvertercalculator.com/length/chains-to-fathoms/)