Convert Foot (ft) to Fathom (US Survey) (fath (US)) instantly.
About these units
Foot (ft)
A foot, equal to 12 inches, has been used for thousands of years and likely originated from the length of a human foot. Though early definitions varied, the modern standard foot—established internationally in 1959—provides a stable and consistent reference. The foot remains the foundation of architectural and construction measurements in the United States, influencing everything from lumber dimensions to ceiling heights and room layouts. Because the foot is intuitively relatable to human scale, people often estimate heights, furniture sizes, and walking distances in feet. In aviation, altitude is universally measured in feet worldwide, even in countries that otherwise use metric units—an unusual but deeply embedded global convention. The foot's persistence shows how cultural inertia can remain strong even when a unit predates modern scientific measurement.
Fathom (US Survey) (fath (US))
The US Survey Fathom is defined as 6 US Survey Feet (~1.8288 meters), identical in proportion to the traditional fathom but scaled to the US Survey Foot. Maritime surveys, early river navigation, and hydrographic measurements relied on this unit for determining depths and plotting charts. In terrestrial applications, the fathom occasionally served as a practical measure for large structures or obstacles. Although less relevant in contemporary usage, understanding the US survey fathom is crucial for interpreting historical navigation data, nautical charts, and engineering projects using older measurement systems.