How this calculator works
The acre is defined as exactly 43,560 square feet, and since the international foot is exactly 0.3048 m, one square foot is exactly 0.09290304 m², making the acre exactly 4046.8564224 m². Historic US survey acres differ slightly. This converter uses the international foot throughout.
Formula
result = value × F(from) ÷ F(to), where F is the exact square metres per unit: 1 ft² = 0.09290304 m²; 1 acre = 43,560 ft² = 4046.8564224 m².
Worked example
2.5 acres to square feet: 2.5 × 43,560 = 108,900 ft². 1 acre to square metres: 4046.8564224 m².
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Frequently asked questions
How long is each side of an acre?
An acre is a unit of area, not shape. A square acre measures about 208.71 ft on a side, but a long narrow parcel of 43,560 ft² is equally one acre.
Why would an old deed show a slightly different acre?
Historic US surveys used the US survey foot, which gives an acre of about 4046.8726 m². US survey foot definitions were retired in 2023; old deeds may still record them.
Can I convert square feet back to acres?
Yes. Choose acres as the result unit, or divide the square footage by 43,560. Both units are defined exactly, so the reverse uses the same factor.