Convert Square Inch (in²) to Acre (US Survey) (ac (US)) instantly.
About these units
Square Inch (in²)
A square inch represents the area of a one-inch by one-inch square. It is indispensable in engineering, manufacturing, machine design, and consumer product specifications. Mechanical components, gasket areas, electronic device screens, and pipe cross-sections are often measured in square inches. Because imperial units are deeply rooted in American manufacturing, the square inch enables precise communication among engineers and technicians. The unit remains important in pressure measurement as well—psi (pounds per square inch) combines force and area into one of the most widely recognized engineering units worldwide.
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.