Acres to Square Feet Converter (ac to ft²)
1 acre = 43,560 ft² exactly. Convert acres to square feet for house lots, zoning minimums and site plans, with acre and sq ft charts.
Square Foot (ft²) = Acre (ac) × 43560
Acre (ac): The acre used here is 43,560 international square feet, exactly 4,046.8564224 m². Historical US survey acres are slightly larger, so check the foot definition when interpreting old survey records.
Square Foot (ft²): A square foot is the area of a square one international foot on each side, exactly 0.09290304 m² or 144 square inches. Historical areas based on the US survey foot use a slightly different factor.
| Acre (ac) | Square Foot (ft²) |
|---|---|
| 1 | 43560 |
| 5 | 217800 |
| 10 | 435600 |
| 25 | 1089000 |
| 50 | 2178000 |
| 100 | 4356000 |
US lots are often described in acres, but house plans, setback diagrams and many zoning minimums are written in square feet, so builders and buyers switch between the two constantly. One acre is exactly 43,560 square feet in both US and British customary measure, and with the international foot of 0.3048 m that definition fixes everything on this page.
Because 43,560 is not a round number, fractions of an acre are where mistakes creep in. A quarter acre is 10,890 ft², a third of an acre is 14,520 ft² and a tenth of an acre is 4,356 ft². An acre also has no fixed shape: a square acre is about 208.7 ft on each side, but a long, narrow lot of the same area counts just as much.
How to use this tool
- Type a value in the Acre box to see it in square feet, or type in the Square Foot box to convert the other way.
- Press ⇄ to swap the two units, or Load example for a typical value.
- Check the charts below for common values; for other units, open the Area converter.
Formula
Square Foot (ft²) = Acre (ac) × 43560
Acre (ac) = Square Foot (ft²) × 0.0000229568411387
Both factors come from exact definitions: 1 square foot = 0.0000229568411387 acres and 1 acre = 43560 square feet (shown to 12 significant digits).
Example
Two conversions worked with the same factors the converter uses:
0.25 ac × 43560 = 10890 ft²
21780 ft² × 0.0000229568411387 = 0.5 ac
Acre to Square Foot chart
Common values from acres to square feet, rounded to four decimal places.
| Acre (ac) | Square Foot (ft²) |
|---|---|
| 0.01 | 435.6 |
| 0.05 | 2,178 |
| 0.1 | 4,356 |
| 0.11 | 4,791.6 |
| 0.125 | 5,445 |
| 0.15 | 6,534 |
| 0.17 | 7,405.2 |
| 0.2 | 8,712 |
| 0.25 | 10,890 |
| 0.3 | 13,068 |
| 0.3333 | 14,520 |
| 0.4 | 17,424 |
| 0.5 | 21,780 |
| 0.6 | 26,136 |
| 0.75 | 32,670 |
| 1 | 43,560 |
| 1.25 | 54,450 |
| 1.5 | 65,340 |
| 2 | 87,120 |
| 2.5 | 108,900 |
| 3 | 130,680 |
| 5 | 217,800 |
| 10 | 435,600 |
| 20 | 871,200 |
Square Foot to Acre chart
The reverse direction for values people often look up.
| Square Foot (ft²) | Acre (ac) |
|---|---|
| 1,000 | 0.023 |
| 2,500 | 0.0574 |
| 4,000 | 0.0918 |
| 5,000 | 0.1148 |
| 6,000 | 0.1377 |
| 7,500 | 0.1722 |
| 8,000 | 0.1837 |
| 10,000 | 0.2296 |
| 15,000 | 0.3444 |
| 20,000 | 0.4591 |
| 21,780 | 0.5 |
| 30,000 | 0.6887 |
| 43,560 | 1 |
| 87,120 | 2 |
House lots and fields in acres
| Lot or field | Acre (ac) | Square Foot (ft²) |
|---|---|---|
| Eighth-acre house lot | 0.125 | 5,445 |
| Quarter-acre house lot | 0.25 | 10,890 |
| Half-acre house lot | 0.5 | 21,780 |
| Furlong by chain, the traditional shape of an acre | 1 | 43,560 |
| American football field, end zones included | 1.3223 | 57,600 |
| Five-acre minimum lot in some rural zoning | 5 | 217,800 |
Quick mental estimate
Multiply by 44,000, then take off 1%: 2.5 acres → 110,000 − 1,100 = 108,900 ft². Since 44,000 less 1% is exactly 43,560, the shortcut has no error at all.
Use the converter or the charts when the exact figure matters.
The two units
Acre (ac): The acre used here is 43,560 international square feet, exactly 4,046.8564224 m². Historical US survey acres are slightly larger, so check the foot definition when interpreting old survey records.
Square Foot (ft²): A square foot is the area of a square one international foot on each side, exactly 0.09290304 m² or 144 square inches. Historical areas based on the US survey foot use a slightly different factor.
Frequently asked questions
How many square feet is half an acre?
21,780 ft². That is roughly a lot 100 ft wide and 218 ft deep, or a square about 147.6 ft on each side.
Why is an acre 43,560 square feet?
The acre was defined as a strip one furlong long and one chain wide: 660 ft × 66 ft = 43,560 ft². The same area can be written as 10 square chains or 4,840 square yards.
How do I find the acreage of a lot from its dimensions?
Multiply length by width in feet and divide by 43,560. A rectangle of 150 ft by 290 ft is 43,500 ft², just under one acre; for triangles and other shapes, the area calculator works out the square footage first.
How precise is the result?
The converter uses the exact definitions above with browser floating-point arithmetic and shows up to 12 significant digits. The charts round to four decimal places for reading.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/acre-to-square-foot-converter/
Cite or embed this tool
kakaoCalc. (2026, November 8). Acres to Square Feet Converter (ac to ft²). https://kakao.mobile/tools/acre-to-square-foot-converter/
“Acres to Square Feet Converter (ac to ft²).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/acre-to-square-foot-converter/.
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