Convert Nautical Mile to Fathom (nmi → ftm)
The nautical mile is the international navigation unit for marine and aviation, equal to one minute of latitude.
Nautical Mile to Fathom Conversion Table
10 common values| Nautical Mile | Fathom |
|---|---|
| 1 nmi | 1,012.6859 ftm |
| 5 nmi | 5,063.4296 ftm |
| 10 nmi | 10,126.859 ftm |
| 25 nmi | 25,317.148 ftm |
| 50 nmi | 50,634.296 ftm |
| 100 nmi | 101,268.59 ftm |
| 250 nmi | 253,171.48 ftm |
| 500 nmi | 506,342.96 ftm |
| 1,000 nmi | 1,012,685.9 ftm |
| 5,000 nmi | 5,063,429.6 ftm |
How to Convert Nautical Mile to Fathom Manually
Step by StepConverting nautical miles to fathoms is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in nautical milesStart with the number of nautical miles (nmi) you want to convert.
- 2Multiply by 1,012.6859The conversion factor from nmi to ftm is 1,012.6859. Multiply your value by this number.
- 3Read the result in fathomsThe result is your value in fathoms (ftm).
Formula
Multiply the value in nautical miles by 1,012.6859. For the reverse direction, multiply by 0.000987.
ftm = nmi × 1,012.6859nmi = ftm × 0.000987Tips
Use these in everyday conversions- 1 nautical mile = 1.852 km = 1.151 statute miles.
- A knot (1 nmi/h) equals 1.852 km/h — remember this for weather and sailing reports.
- Latitude is measured in degrees and minutes; one minute of latitude equals exactly one nautical mile.
Common Mistakes
Avoid these- Confusing nautical miles with statute miles — the 15% difference matters in flight planning.
- Reading knots as km/h on weather reports — a 40-knot wind is 74 km/h, not 40.
- Using nautical miles on land — outside navigation contexts, use kilometres or statute miles.
About Nautical Mile and Fathom
What is the Nautical Mile?
The nautical mile equals exactly 1,852 meters and is the international standard distance unit for marine navigation, aviation, and polar geography. It was originally defined as one minute of arc along a meridian — meaning 60 nautical miles equal one degree of latitude. This relationship makes the nautical mile uniquely useful for charts: a navigator can read distance directly off the latitude scale of any map. Adopted internationally in 1929, the nautical mile is used by virtually all maritime nations and in international aviation regulations. The related speed unit is the knot (1 nautical mile per hour). The nautical mile is roughly 1.151 statute miles or 1.852 km. Distinct from the older British nautical mile (6,080 ft) and the US nautical mile (6,080.20 ft), the international nautical mile is now standard worldwide.
- Marine navigation and nautical charts
- Commercial and military aviation distances
- International maritime law (territorial waters = 12 nmi)
Territorial waters extend 12 nautical miles from the coastline. London Heathrow to New York JFK is about 3000 nmi.
What is the Fathom?
The fathom equals exactly 1.8288 meters or 6 feet and is the traditional marine depth unit. The word derives from the Old English 'fæðm,' meaning the span of outstretched arms — historically the distance a sailor could measure rope by stretching it from fingertip to fingertip. Used since antiquity for sounding water depth (lowering a weighted line and counting fathom marks), the fathom remains common in nautical charts, diving manuals, and marine literature. Famous from Mark Twain's pen name (a riverboat lead's call meaning 'safe water,' 2 fathoms or 12 feet) and Shakespeare's 'full fathom five,' the unit retains cultural resonance. Modern oceanographic science prefers the meter, but the fathom persists in fishing, recreational diving, and historical maritime contexts. The fathom relates to the foot (1 fathom = 6 ft) and the yard (1 fathom = 2 yd).
- Water depth on older US nautical charts
- Maritime literature and historical navigation
- Sport diving and scuba depth references in the US
A "mark twain" reading — made famous by the Mississippi riverboats — meant 2 fathoms (3.66 m) of water, the minimum safe depth.