Convert Earth's Equatorial Radius (R⊕) to Fathom (fath) instantly.
About these units
Earth's Equatorial Radius (R⊕)
The Earth's equatorial radius is approximately 6,378.1 km. This distance represents the radius measured along the equator, where Earth's rotational bulge makes it slightly larger than the polar radius. Geodesists, cartographers, and astronomers use the equatorial radius for mapping, satellite positioning, and calculating gravitational effects. It is fundamental to defining the shape of the Earth as an oblate spheroid rather than a perfect sphere. Precise knowledge of R⊕ enables accurate navigation, climate modeling, and orbital calculations, forming the basis for modern geodesy and Earth observation systems.
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.