Convert Square Rod (rod²) to Acre (US Survey) (ac (US)) instantly.
About these units
Square Rod (rod²)
A square rod, also known as a perch or pole in some traditions, equals the area of a square one rod on each side (1 rod = 16.5 feet). This results in 272.25 square feet. Square rods were widely used in medieval English farming and early American surveying to measure garden plots, small fields, and building sites. Because land taxes were often assessed per rod, the unit became a practical economic tool as well. Though no longer widely used, the square rod appears in historical deeds and archival surveys, making it critical for land historians and legal property research.
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.