How many square feet are in an acre?
There are 43,560 square feet in one acre, which is 1 acre in square feet, and a square yard is 9 square feet, says NIST Handbook 44. [2] NIST also lists the acre, on the U.S. survey foot, as 4,046.873 square meters. [1]
Worked example
2.5 acres x 43,560 = 108,900 square feet. Divided by 9, that is 12,100 square yards. Going back, 108,900 / 43,560 = 2.5 acres. If one acre were a square, each side would be the square root of 43,560, which is 208.71 ft.
How do I convert square feet to acres?
Divide the square feet by 43,560. For example, 10,000 square feet is 10,000 / 43,560 = 0.2296 acres. Pick Square feet to acres above and type the square feet.
Acres and square feet for common sizes
A quarter acre is 10,890 square feet and half an acre is 21,780. The second table goes the other way, from square feet to acres.
| Acres | Square feet | Square yards |
|---|---|---|
| 1/8 | 5,445 | 605 |
| 1/4 | 10,890 | 1,210 |
| 1/3 | 14,520 | 1,613 |
| 1/2 | 21,780 | 2,420 |
| 1 | 43,560 | 4,840 |
| 2 | 87,120 | 9,680 |
| 3 | 130,680 | 14,520 |
| 4 | 174,240 | 19,360 |
| 5 | 217,800 | 24,200 |
| 10 | 435,600 | 48,400 |
| Square feet | Acres |
|---|---|
| 1,000 | 0.023 |
| 5,000 | 0.1148 |
| 10,000 | 0.2296 |
| 15,000 | 0.3444 |
| 20,000 | 0.4591 |
How do I find the acres of a lot?
Multiply the length by the width, in feet, and divide by 43,560. For an odd shape, split the lot into rectangles and triangles and add their areas. The room square footage calculator and the square footage calculator find those areas.
Spreadsheet formula
In a spreadsheet, =A1*43560 turns acres in cell A1 into square feet, and =A1/43560 turns square feet into acres.
Common mistakes and limits
- Reading a fraction as a decimal. A quarter acre is 0.25, and a third of an acre is 0.3333, not 0.33.
- Mixing up the direction. Pick Acres to square feet or Square feet to acres before you type.
- What this tool does not cover: square miles, metric units, the boundaries of a lot and the difference between a survey and a plan.
Frequently asked questions
How do I convert square feet to acres?
Divide the square feet by 43,560. For example, 10,000 square feet is 10,000 / 43,560 = 0.2296 acres.
How do I calculate acres from the length and width of a lot?
Multiply the length by the width, in feet, for square feet, then divide by 43,560. A lot 200 ft by 150 ft is 30,000 square feet, which is 0.6887 acres.
How long is each side of a square acre?
NIST Handbook 44 says that if an acre is a square, the length of one side is approximately equal to the square root of 43,560 square feet, which is 208.710 ft. [2]
Does this convert square miles or square meters?
No. This page converts acres, square feet and square yards. NIST lists the acre as 4,046.873 square meters on the survey foot, but we do not convert metric units here. [1]
Sources and references
- National Institute of Standards and Technology (NIST). NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically (SP 811, accessed November 2026). Used for: the acre in square meters.
- National Institute of Standards and Technology (NIST). Handbook 44, Appendix C, General Tables of Units of Measurement (2026, accessed November 2026). Used for: the 43,560 square feet in an acre, the 9 square feet in a yard, and the side of a square acre.
How we use sources: methodology.
Estimates only. Confirm quantities with your supplier. See the disclaimer. Found a wrong result? Report an error.