This page converts nautical miles into fathoms using the factor 1012.685914, and shows the reverse figure alongside it. Both units measure length, which is why one number does the whole job.
Exactly 1,852 metres — one minute of latitude, the basis of marine and air navigation. Six feet, the traditional depth unit on marine charts.
The mil and the millimetre are not the same thing and are out by a factor of about forty. A mil is one thousandth of an inch — 0.0254 mm — and a spec sheet that quotes film thickness in mils means the small unit. British drawings write the same size as "thou". The tables underneath give both a plain step-by-step lookup and a list of real quantities expressed in fathoms, so you can sanity-check whether your answer is a plausible size.
The formula
nautical miles- The amount you are converting, in nautical miles
1012.68591426- The exact number of fathoms in one nautical mile
fathoms- The converted result
How it works, step by step
- Enter the value in nautical miles.
- It is multiplied by 1012.68591426, the exact factor between the two units.
- The answer is shown in fathoms, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
An Olympic pool: 0.027 nmi in fathoms
Take an olympic pool, roughly 0.027 nmi. The conversion is a single multiplication — 0.027 × 1012.69 — giving 27.3425 ftm. Because the relationship is proportional, doubling the input doubles the answer to 54.685 ftm.
A marathon: 22.8 nmi in fathoms
At 22.8 nmi (a marathon), the same quantity in fathoms is 22.8 × 1012.69 = 23,089.2 ftm. One nautical mile is 1012.69 fathoms, so the numbers grow as expected.
How to read your score
Frequently asked questions
How many fathoms are in one nautical mile?
Exactly 1012.68591426. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert nautical miles to fathoms?
fathoms = nautical miles × 1012.68591426. Reversed, nautical miles = fathoms ÷ 1012.68591426, which is the same as multiplying by 0.00098747300216.
Which is the bigger unit, the nautical mile or the fathom?
The nautical mile. One nautical mile equals 1012.69 fathoms.
What does this quantity actually measure?
Both units measure length. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a nautical mile?
Exactly 1,852 metres — one minute of latitude, the basis of marine and air navigation.
What is a fathom?
Six feet, the traditional depth unit on marine charts.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Is there a quick way to do nmi to ftm in my head?
Plenty of people do this in their head: multiply by 1000 instead of using the exact factor 1012.685914. At 100 that shortcut gives 100,000 fathoms, off by 1269 fathoms or about 1.25%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Nautical Miles to fathoms reference tables
| Nautical Miles | Fathoms |
|---|---|
| 0.5 nmi | 506.343 ftm |
| 1 nmi | 1012.69 ftm |
| 2 nmi | 2025.37 ftm |
| 3 nmi | 3038.06 ftm |
| 5 nmi | 5063.43 ftm |
| 10 nmi | 10,126.9 ftm |
| 20 nmi | 20,253.7 ftm |
| 25 nmi | 25,317.1 ftm |
| 50 nmi | 50,634.3 ftm |
| 75 nmi | 75,951.4 ftm |
| 100 nmi | 101,269 ftm |
| 250 nmi | 253,171 ftm |
| 500 nmi | 506,343 ftm |
| 1000 nmi | 1.01269e+06 ftm |
| 5000 nmi | 5.06343e+06 ftm |
Exact factor: 1 nautical mile = 1012.68591426 fathoms.
| Quantity | nmi | ftm |
|---|---|---|
| A credit card’s long edge | 4.622e-05 nmi | 0.04681 ftm |
| A door height | 0.001097 nmi | 1.111 ftm |
| An Olympic pool | 0.027 nmi | 27.34 ftm |
| The Eiffel Tower | 0.1782 nmi | 180.4 ftm |
| A marathon | 22.78 nmi | 2.307e+04 ftm |
| Earth’s diameter | 6880 nmi | 6.967e+06 ftm |
Published reference values, converted with the same factor this page uses.