Feet to Fathoms
An instant feet-to-fathoms converter, with the formula and a reference table below.
| Feet | Fathoms |
|---|---|
| 1 ft | 0.166667 ftm |
| 2 ft | 0.333333 ftm |
| 3 ft | 0.5 ftm |
| 5 ft | 0.833333 ftm |
| 10 ft | 1.666667 ftm |
| 25 ft | 4.166667 ftm |
| 50 ft | 8.333333 ftm |
| 100 ft | 16.666667 ftm |
How to use
- Enter a value in the Feet field.
- The Fathoms figure appears immediately — no button to press.
- Typing in the Fathoms field converts back to Feet the same way.
- Use the reference table for the values that come up most often.
Feet to Fathoms formula
To convert feet to fathoms, multiply by 0.166666667.
ftm = ft × 0.166666667
Put another way, one foot is exactly 1/6 of a fathom.
Why this factor: the foot and the fathom are both defined against the meter, so dividing one definition by the other gives 0.166666667 directly. Both definitions are set out in full below.
To go the other way, divide by 0.166666667 — or use the Fathoms to Feet converter, which is the same calculation reversed.
Worked example
Given 100 ft, multiplying by 0.166666667 yields 16.666667 ftm.
100 ft × 0.166666667 = 16.666667 ftm
The converter above does this for any value you type, in either direction.
What is a foot?
A foot is twelve inches, the primary unit for human-scale dimensions in the US.
Definition: Exactly 0.3048 meter since 1959 — one third of the international yard.
Where it is used: Building heights, room dimensions, aviation altitude worldwide, and personal height in the US and UK.
Worth knowing: The US survey foot, very slightly longer, was used in land surveying until it was officially retired at the end of 2022.
What is a fathom?
A fathom is six feet, the traditional unit for water depth.
Definition: Six international feet, so exactly 1.8288 meters.
Where it is used: Nautical charts, depth soundings, and anchor and cable lengths.
Feet vs Fathoms
The foot is an imperial unit while the fathom is a specialized unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many fathoms are in a foot?
One foot equals 0.166666667 fathoms.
What is the formula to convert feet to fathoms?
Multiply the number of feet by 0.166666667. To reverse it, divide by 0.166666667 instead.
How do I convert fathoms back to feet?
Divide by 0.166666667, which is the same as multiplying by 6.
How many fathoms are in 10 feet?
10 ft works out to 1.666667 ftm.
Is there anything to watch out for with feet?
The US survey foot, very slightly longer, was used in land surveying until it was officially retired at the end of 2022.
How is the foot defined?
Exactly 0.3048 meter since 1959 — one third of the international yard.