Convert acres to sq ft (acre to sq ft)

One acre is exactly 43,560 square feet. That ratio belongs to the customary system itself and is much older than any link to metric: the 1959 international yard and pound agreement later fixed the yard and the pound against the meter and the kilogram, but it left the ratios between customary units (feet to the yard, ounces to the pound, cups to the gallon) exactly as they were.

Worked through: 1 acre x 43,560 = 43,560 sq ft.

Going the other way, one square foot is 0.0000229568 acres.

To convert without a calculator, multiply by 43,560. Rounding that to 44,000 is within 1% for most purposes.

An acre is exactly 43,560 square feet, which is 10 square chains in the old surveyor's system, a chain being 66 feet. The number is arbitrary-looking because it descends from how much a yoke of oxen could plow in a day.

Precision is worth matching to the input. A measurement given as 0.1 acre carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.