Divide by 43,560
One acre is exactly 43,560 square feet, so dividing your square footage by that number gives acres. The odd figure is not arbitrary: an acre was historically a strip 660 ft long by 66 ft wide (660 × 66 = 43,560). To go the other way, multiply acres by 43,560.
Common square-foot areas in acres
| Square feet | Acres | Typical use |
|---|---|---|
| 1,000 ft² | 0.023 ac | Small building footprint |
| 5,000 ft² | 0.115 ac | Small city lot |
| 10,000 ft² | 0.230 ac | Standard suburban lot |
| 21,780 ft² | 0.500 ac | Half-acre parcel |
| 43,560 ft² | 1.000 ac | One acre |
| 87,120 ft² | 2.000 ac | Two-acre plot |
| 217,800 ft² | 5.000 ac | Small holding |
A quarter-acre lot (10,890 ft²) is roughly 100 ft by 109 ft — the common size for a US suburban home plot.
Worth knowing before you rely on the number
- Acres are not hectares. One acre is 0.4047 hectares, so an acre is under half a hectare. Going the other way, one hectare is 2.471 acres.
- 640 acres make a square mile. Rural US land is often described in these blocks, so a "quarter section" is 160 acres, or 6,969,600 ft².
- Measure the whole lot, not just the building. Acreage covers the entire parcel. To get it from dimensions, multiply length by width first, then divide by 43,560.
Common questions
How many square feet are in an acre?
Exactly 43,560 square feet. The figure comes from the old definition of an acre as a strip 660 feet long by 66 feet wide, which multiplies out to 43,560.
How do I convert square feet to acres?
Divide the square footage by 43,560. For example, 10,000 square feet divided by 43,560 is about 0.23 acres.
How do I get acres from a lot in feet?
Multiply the length by the width in feet to get the area, then divide by 43,560. A 300 by 200 foot lot is 60,000 square feet, which is 1.38 acres.
