Convert Square Foot (US Survey) (ft² (US)) to Acre (US Survey) (ac (US)) instantly.
About these units
Square Foot (US Survey) (ft² (US))
The US survey square foot is defined using the US survey foot and differs minutely from the international square foot. While the difference is negligible in everyday contexts, in land surveying even tiny discrepancies matter because property boundaries, right-of-way extents, and engineering alignments may accumulate errors over long distances. Surveyors and civil engineers must interpret historical documents using survey-based values to ensure legal consistency with old plats, deeds, and boundary descriptions.
Acre (US Survey) (ac (US))
The US survey acre is based on the US survey foot, making it slightly different from the international acre. With a value of 43,560 survey-square feet, it appears extensively in historical property records and federal land surveys. Because millions of acres in the United States were mapped using PLSS, the survey acre remains necessary for interpreting legal land rights, even though modern mapping often uses metric units or the international foot. This specialized acre illustrates how subtle unit differences can survive for centuries due to legal and administrative inertia.