Nautical Miles to Fathoms
Convert nautical miles to fathoms instantly — one nautical mile is 1012.69 fathoms.
| Nautical Miles | Fathoms |
|---|---|
| 1 nmi | 1012.685914 ftm |
| 2 nmi | 2025.371829 ftm |
| 3 nmi | 3038.057743 ftm |
| 5 nmi | 5063.429571 ftm |
| 10 nmi | 10126.859143 ftm |
| 25 nmi | 25317.147857 ftm |
| 50 nmi | 50634.295713 ftm |
| 100 nmi | 101268.591426 ftm |
How to use
- Enter a value in the Nautical Miles field.
- The Fathoms figure appears immediately — no button to press.
- Typing in the Fathoms field converts back to Nautical Miles the same way.
- Use the reference table for the values that come up most often.
Nautical Miles to Fathoms formula
Converting nautical miles to fathoms is a single multiplication by 1012.68591.
ftm = nmi × 1012.68591
Why this factor: the nautical mile and the fathom are both defined against the meter, so dividing one definition by the other gives 1012.68591 directly. Both definitions are set out in full below.
To go the other way, divide by 1012.68591 — or use the Fathoms to Nautical Miles converter, which is the same calculation reversed.
Worked example
Start with 5 nmi. Multiply by 1012.68591 to get 5063.429571 ftm.
5 nmi × 1012.68591 = 5063.429571 ftm
The converter above does this for any value you type, in either direction.
What is a nautical mile?
A nautical mile is the distance unit of sea and air navigation, chosen so it tracks latitude on a chart.
Definition: Exactly 1,852 meters, fixed by the 1929 International Extraordinary Hydrographic Conference. It approximates one arcminute of latitude.
Where it is used: Marine and aviation navigation, maritime boundaries, and the basis of the knot (one nautical mile per hour).
Worth knowing: About 15% longer than a statute mile — mixing the two is a classic navigation error.
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.
Nautical Miles vs Fathoms
The nautical mile and the fathom belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many fathoms are in a nautical mile?
One nautical mile equals 1012.68591 fathoms.
What is the formula to convert nautical miles to fathoms?
Multiply the number of nautical miles by 1012.68591. To reverse it, divide by 1012.68591 instead.
How do I convert fathoms back to nautical miles?
Divide by 1012.68591, which is the same as multiplying by 0.000987473002.
How many fathoms are in 10 nautical miles?
10 nmi works out to 10126.859143 ftm.
Is there anything to watch out for with nautical miles?
About 15% longer than a statute mile — mixing the two is a classic navigation error.
How is the nautical mile defined?
Exactly 1,852 meters, fixed by the 1929 International Extraordinary Hydrographic Conference. It approximates one arcminute of latitude.