US Survey Foot (ft (US))

US land surveyHistorical unit (no longer in standard use)

Exactly 1200/3937 meters, about 2 parts per million longer than the international foot. Retired in the US at the end of 2022 but still found in older land records.

1 US survey foot = 0.3048006096 meters (approximately).

About the US survey foot

Two feet coexisted in the United States for sixty-three years. The Mendenhall Order of 1893 tied American units to the metre at 39.37 inches to the metre, which makes the survey foot exactly 1200/3937 m, about 0.3048006 m. In 1959 the international foot was set at exactly 0.3048 m for industry and trade, but the older foot was kept for geodetic work until control networks could be readjusted. That readjustment was finished in 1986, yet the survey foot stayed in use.

The two differ by about 2 parts per million. That is trivial for a house lot but adds up in the State Plane Coordinate System, where coordinates can lie hundreds of thousands of feet from their origin. NIST and the National Geodetic Survey announced that the survey foot should not be used after December 31, 2022, with the international foot replacing it, leaving it for historic and legacy data. Before that, state laws varied: about 40 of 56 jurisdictions based surveying on the survey foot, six on the international foot, and ten did not specify.

Sources: NIST: U.S. survey foot; Wikipedia: Foot (unit)

US Survey Foot conversion chart

1 US survey foot expressed in every other length unit:

More US land survey units

• US survey mile (length)
• US survey acre (area)
• section (area)
• township (area)

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