Land Area to Acres Calculator
The land area to acres calculator converts an area measured in square feet into acres using the exact definition of the acre. The method is a single fixed factor: one acre is defined as 43,560 square feet, so any area in square feet divided by 43,560 gives the area in acres. The acre is a US customary land unit, and because the factor is exact the conversion is precise rather than approximate. If you have a rectangular parcel, multiply its length by its width in feet to get the square footage first, then divide by 43,560. For an irregular boundary, find the total square feet from a survey or measured plan and apply the same single step, because the acre factor does not depend on the shape of the land. Enter your own square footage to size a building lot, work out the acreage of a field, or check a parcel description against a deed. The companion fact that a square mile holds 640 acres falls straight out of the same factor. Every figure here is computed deterministically from the conversion shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step and trust the result.
Acres equal the area in square feet divided by the square feet in an acre: acres = square feet / 43,560. A parcel of 87,120 sq ft is 2.00 acres. The factor 43,560 is exact, so the conversion is precise.
Square feet to acres formula
Acres = A / 43,560
A = area in square feet
43,560 = square feet in one acre (exact)
The acre is defined as 43,560 square feet. Dividing any area in square feet by that fixed factor returns the area in acres. The factor is exact, so the conversion introduces no rounding of its own.
Worked example
A rectangular field measures 363 feet by 240 feet. Find its area in acres.
- Area = 363 x 240 = 87,120 square feet
- Acres = 87,120 / 43,560
- Acres = 2.00
The field is 2.00 acres. The 87,120 square foot figure is the calculator's default input, so the result above matches the widget exactly.
Common areas in acres
Square feet converted to acres at the exact 43,560 factor.
| Square feet | Acres |
|---|---|
| 10,000 | 0.23 |
| 43,560 | 1.00 |
| 87,120 | 2.00 |
| 217,800 | 5.00 |
| 435,600 | 10.00 |
Survey and geodetic units: US National Geodetic Survey (NOAA).
Land area to acres calculator: frequently asked questions
How many square feet are in an acre?
One acre contains exactly 43,560 square feet. The acre is a US customary unit of land area, historically the area one yoke of oxen could plough in a day. To convert any area in square feet to acres, divide the square feet by 43,560. To go the other way, multiply acres by 43,560 to get square feet.
How do I convert square feet to acres?
Divide the area in square feet by 43,560. For example, 87,120 square feet divided by 43,560 equals 2 acres. If you measured a rectangular parcel in feet, first multiply length by width to get square feet, then divide by 43,560 to get the area in acres.
What is the US survey foot?
The acre is defined in terms of the foot, and the United States historically used a survey foot that was very slightly longer than the international foot. As of 2023 the US has standardised on the international foot for new work. For everyday land area the difference is negligible, but precise cadastral survey records may still reference the survey foot.
How many acres is a square mile?
A square mile contains 640 acres. A mile is 5,280 feet, so a square mile is 5,280 times 5,280, or 27,878,400 square feet. Dividing that by 43,560 square feet per acre gives 640 acres. This is why a standard public-land survey section, one square mile, is described as 640 acres.
Does an irregular parcel convert the same way?
Yes. Whatever the shape, once you know the total area in square feet you divide by 43,560 to get acres. For an irregular boundary, find the area in square feet first using survey coordinates or a measured plan, then apply the same conversion. The acre factor does not depend on the shape of the land.
Official sources
- Survey foot, geodetic datums and land measurement standards: US National Geodetic Survey (NOAA). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.