Acres and square feet
The international acre is exactly 4,046.8564224 square meters, or 43,560 square feet (one chain by one furlong). Land and property lots in the US, UK, Canada and Australia are sold by the acre.
A square foot is a square 1 foot on each side: exactly 0.09290304 square meters, or 144 square inches. Home sizes, rents, flooring and office space in the US and Canada are quoted in square feet.
Worked example
Convert 0.25 ac: 0.25 × 43,560 = 10,890, so 0.25 acres is 10,890 square feet. Likewise 0.1 ac = 4,356 ft².
Estimating in your head
Multiply by 44,000 for a quick figure; it is off by about 1%. For 0.25 ac that gives 11,000 ft², against 10,890 exactly.
Going the other way
To convert square feet to acres, divide by 43,560 (or multiply by 0.0000229568411387). The swap button between the boxes opens that page.
How this works
ft² = ac × 43,560
1 ac = 4,046.8564224 m² and 1 ft² = 0.09290304 m², both by definition, so the factor is their ratio: 43,560 exactly. Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.
Frequently asked
How many square feet are in a acre?
1 acre = 43,560 square feet, exactly. The value follows from the unit definitions, so it never changes.
How do I convert acres to square feet?
Multiply by 43,560. For example, 0.1 ac × 43,560 = 4,356 ft².
What is 0.5 ac in square feet?
0.5 ac = 21,780 ft². The table next to the converter lists more common values.
Is the result rounded?
Only on screen. The page computes with the exact definitions and removes floating-point noise past 15 significant digits; pick 3 to 12 significant figures, or use Copy result for the full value.
Sources
- NIST SP 811 Appendix B.8 — Factors for units listed alphabetically
- Federal Register 59-5442 (1959) — Refinement of values for the yard and the pound
- Wikipedia — Acre
Reviewed Oct 17, 2026 · test vectors fixtures/units/area/acres-to-square-feet/