One of the more peculiar SI measurement units, defined as 12/39.37 (approximately 0.304800609601) meters . One US Survey Foot = approximately 1.000002 feet.

As the name might suggest, the US Survey foot is used mostly by land surveyors in the United States.

Most of the State Plane Coordinate Systems adopted by various states in the in the 1920's through the 1950's measure their coordinates in US Survey Feet. Because of a datum change, most have these have been replaced by new systems defining coordinates in meters instead. However, some states allow the use of either unit.