Convert Nautical Mile (nmi) to Fathom (fath) instantly.
About these units
Nautical Mile (nmi)
The nautical mile is a unit designed specifically for navigation. Its definition—exactly 1,852 meters—originated from the idea that one nautical mile equals one minute of arc along Earth's meridian. This geometric relationship makes nautical miles incredibly convenient for charting and navigation because latitude coordinates are given in degrees, minutes, and seconds. Aviation and maritime industries use nautical miles exclusively for distance, and knots (nautical miles per hour) for speed. Because Earth's shape and size are fundamental to navigational calculations, using nautical miles avoids the complexities that would arise if statute miles or kilometers were used instead. The unit remains globally standardized and universally understood in professional navigation.
Fathom (fath)
A fathom is equal to 6 feet and is historically associated with maritime measurement. Its origins may lie in the approximate span of a fully outstretched human arms, which was convenient for measuring rope lengths by hand aboard ships. Sailors used the fathom to estimate water depth through weighted lines, giving rise to the practice of "sounding" the depths. The fathom became a cornerstone unit in nautical life because it fits the human scale while also being large enough to measure significant underwater distances. Charts, sonar readings, and older depth gauges frequently utilized fathoms, although modern equipment increasingly displays depths in meters. Still, many mariners—particularly in regions using imperial measurements—continue to think instinctively in fathoms when estimating safe anchoring or navigating shallow waters. The unit persists as an important piece of maritime history and remains in active use by traditional sailors, divers, and some fishing industries. Its survival reflects the enduring cultural heritage of nautical practice.