One acre is 43,560 square feet. NIST's Handbook 44 defines it as 43,560 ft², equal to 160 square rods or 10 square chains. To convert acres to square feet, multiply by 43,560: 2 acres is 87,120 ft². To convert square feet to acres, divide by 43,560: a 10,000 ft² lot is 0.2296 acre.
How many square feet are in an acre?
The acre is a US customary unit of area. NIST lists it as 43,560 ft², and the square foot is exactly 0.09290304 m² on the international foot. Multiplying gives 43,560 × 0.09290304 = 4,046.8564 m², which is 0.40468564 hectare. The acre therefore sits between the square yard and the square mile:
| Unit | In square feet |
|---|---|
| 1 square yard | 9 |
| 1 acre | 43,560 (4,840 square yards) |
| 1 square mile | 27,878,400 (640 acres) |
The number looks odd because the acre was never built from a square. It comes from a strip 1 furlong long (660 ft) and 1 chain wide (66 ft): 660 × 66 = 43,560.
Formulas
square feet = acres × 43,560
acres = square feet ÷ 43,560
square meters = acres × 4,046.8564
hectares = acres × 0.40468564
Converters: acres to square feet, square feet to acres, acres to hectares, hectares to acres and square feet to square meters.
Acres to square feet chart
| Acres | Square feet | Square meters |
|---|---|---|
| 1/8 | 5,445 | 505.9 |
| 1/4 | 10,890 | 1,011.7 |
| 1/2 | 21,780 | 2,023.4 |
| 1 | 43,560 | 4,046.9 |
| 2 | 87,120 | 8,093.7 |
| 2.5 | 108,900 | 10,117.1 |
| 5 | 217,800 | 20,234.3 |
| 10 | 435,600 | 40,468.6 |
| 40 | 1,742,400 | 161,874.3 |
| 100 | 4,356,000 | 404,685.6 |
Square feet to acres chart
| Square feet | Acres |
|---|---|
| 5,000 | 0.1148 |
| 8,000 | 0.1837 |
| 10,000 | 0.2296 |
| 15,000 | 0.3444 |
| 21,780 | 0.5000 |
| 43,560 | 1.0000 |
Worked examples
Example 1: a quarter-acre lot
A quarter acre is 43,560 ÷ 4 = 10,890 ft². A rectangle of 90 ft by 121 ft has that area (90 × 121 = 10,890), but so does a lot of 100 ft by 108.9 ft.
Example 2: a lot measured in feet
A lot of 100 ft by 150 ft is 15,000 ft². Divided by 43,560 this is 0.344 acre, a little over a third of an acre. The area calculator handles the multiplication for other shapes.
Example 3: how long is the side of a square acre?
If an acre were a square, each side would be the square root of 43,560, which is 208.71 ft. A square 200 ft on a side is 40,000 ft², or 0.918 acre, so a square lot needs about 209 ft per side to reach one acre. NIST's handbook notes that an acre need not be square.
Example 4: acres to hectares
A 40-acre field is 40 × 0.40468564 = 16.19 hectares. Going the other way, 10 hectares is 10 × 2.4710538 = 24.71 acres.
Example 5: acres and square miles
A parcel of 320 acres is half of a square mile, since a square mile is 640 acres. In square feet that is 320 × 43,560 = 13,939,200.
International acre or survey acre?
Until the end of 2022 the US had two feet: the international foot (exactly 0.3048 m) and the US survey foot (about 0.3048006 m). NIST's revised factors list the acre as 4,046.8564224 m² on the international foot and 4,046.872609874 m² on the survey foot, a difference of about 0.0004%. NIST directs that the survey foot be avoided except for historic and legacy uses, so the first value applies in everyday work. In square feet, an acre is 43,560 on both.
Quick ways to estimate
- Acres to square feet: multiply by 40,000 and add 9% (3 acres: 120,000 + 10,800 = 130,800, against the exact 130,680).
- Square feet to acres: divide by 40,000 and subtract about 8% (20,000 ft²: 0.5 − 0.04 = 0.46, against the exact 0.459).
- Check: an acre is a bit less than 44,000 ft² and roughly 4,000 m².
For other conversions with imperial and metric units, see the metric vs imperial guide and the unit converters.