Convert Circular Inch (circ in) to Acre (US Survey) (ac (US)) instantly.
About these units
Circular Inch (circ in)
A circular inch represents the area of a circle with a diameter of exactly one inch. This yields an area of approximately 0.7854 square inches. It is sometimes used in engineering, especially in the sizing of pipes, hydraulic fittings, and certain mechanical components where circular cross-sections dominate. While not as widespread as the square inch, the circular inch offers a more direct representation of the actual shape of round components, reducing the need for manual geometric conversion.
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.