A nautical mile is exactly 1,852 meters.
Nautical miles to Fathoms Converter — nmi to ftm
Convert Nautical mile (nmi) to Fathom (ftm) using the exact conversion factor (1 nautical mile = 1,012.685914 fathom). See the formula, worked examples, conversion table, history, and common uses.
Nautical miles to Fathoms converter
Converter
Length Converter
Convert SI, imperial, US customary, astronomical, scientific, and historical length units.
Context values
Some unit families need one extra value for a physically accurate result.
A fathom is six feet.
Result = input x 1852 / 1.8288.
Length uses the meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Nautical miles to Fathoms
Nautical mile and Fathom both measure length. Nautical mile is most often used for marine and aviation distance and navigation.
Formula
fathoms = nautical miles × 1012.68591426
This factor comes from each unit's defined relationship to the category's base unit: 1 nautical mile equals 1852 base units, and 1 fathom equals 1.8288 base units, so dividing one by the other gives the direct nautical mile-to-fathom factor of 1012.68591426.
Simple example
1 nmi × 1012.685914 = 1,012.685914 ftm
1 nautical mile = 1,012.685914 fathoms.
Real-world example
10 nmi × 1012.685914 = 10,126.85914 ftm
10 nautical miles = 10,126.85914 fathoms.
Conversion table
| Nautical mile (nmi) | Fathom (ftm) |
|---|---|
| 1 nmi | 1,012.685914 ftm |
| 5 nmi | 5,063.429571 ftm |
| 10 nmi | 10,126.85914 ftm |
| 21.0975 nmi | 21,365.14108 ftm |
| 42.195 nmi | 42,730.28215 ftm |
| 100 nmi | 101,268.5914 ftm |
Reverse conversion: Fathom to Nautical mile
1 ftm × 0.0009874730022 = 0.000987473 nmi
1 fathom = 0.000987473 nautical miles.
nautical miles = fathoms × 0.00098747300216
For a page dedicated to this direction, see Fathom to Nautical mile.
Understanding the Nautical mile
Nautical mile (nmi) measures distance. The international nautical mile is defined as exactly 1,852 meters, standardized in 1929. It is classified as a Non-SI unit accepted for use with SI (maritime/aviation).
Where it's used: Used internationally in maritime navigation and aviation.
Uses of the Nautical mile today
- Marine and aviation distance and navigation
- Basis for the knot (nautical miles per hour)
History of the Nautical mile
The nautical mile was historically defined as one minute of latitude along a meridian, directly tying sea navigation to the Earth's geometry, which made it practical for chart-based navigation using a ship's known latitude. The International Hydrographic Bureau standardized it at exactly 1,852 meters in 1929, a value close to the traditional latitude-based definitions used by different countries.
Historical origin. Nautical mile was not the invention of a single named person; it developed through the process described above.
Understanding the Fathom (ftm)
A fathom is six feet.
Nautical mile — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the nautical mile among accepted non-SI units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many fathoms are in 1 nautical mile?
1 nautical mile equals 1,012.685914 fathoms, using the exact defined conversion factor rather than an estimate.
How do I convert nautical mile to fathom?
Multiply the nautical mile value by 1012.685914. The converter above does this instantly to whatever precision you set.
How do I convert fathom back to nautical mile?
Use the reverse factor: 1 fathom equals 0.000987473 nautical miles. You can also use the swap control in the converter above to flip the direction instantly.
What is a nautical mile?
Nautical mile (nmi) measures distance. The international nautical mile is defined as exactly 1,852 meters, standardized in 1929. It is classified as a Non-SI unit accepted for use with SI (maritime/aviation).
What is a fathom?
Fathom (ftm) is a unit of length.
Is the nautical mile to fathom conversion exact?
Yes. The international nautical mile is defined as exactly 1,852 meters, standardized in 1929. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the nautical mile still used today?
Used internationally in maritime navigation and aviation.