How many feet by how many feet equals 1 acre?

Answer 1

43559.45382 ft = 1 acre.

square root of 43559.45832 sq ft = 208.73 ft

-The U.S. acre is actually an even 43,560 (66x660 or 1/8 mi. by 1/80th). The odd decimal comes from improper use of international feet in a U.S. survey acre.

An international acre is 43,560 international feet (exactly 304.8mm each). A U.S. survey acre is still exactly 43,560 feet, they are just very very slightly larger U.S. survey feet which were defined in the late 1890s by the Mendenhall order as 1200/3937 meters (304.8006+ mm).

The difference between international feet and U.S. survey feet is so small as to account for only 1/8 inch per mile distance (or 1/64 sq. in. per square mile). Dividing by 640 to get the variance between U.S. and international acres comes out to about 24.5 millionths of a square inch difference between the two acres.

The correct number of square international feet in a U.S. survey acre is actually 43559.99999992281, not 43.55945832. Not sure where that number was obtained but it makes the difference out to be far larger than it actually is.