How Big Is an Acre?
By AcreBound Editorial Team Updated:
Quick Answer
One acre is 43,560 square feet, about 4,047 square meters or 0.4047 hectares. As a square, each side would be about 209 feet.
It is about 90% of an American football field between the goal lines, or 76% of the whole field with end zones. An acre can take any shape, such as 66 ft × 660 ft.
One acre is 43,560 square feet, which is about 4,047 square meters or 0.4047 hectares. If an acre were a perfect square, each side would be about 209 feet long (208.7, to be exact). Lots are rarely square, so an acre can also be 100 ft × 435.6 ft, or 66 ft × 660 ft. The acre is a measure of area only. It has no set length or width.
An Acre in Other Units
| Unit | One acre equals |
|---|---|
| Square feet | 43,560 |
| Square yards | 4,840 |
| Square meters | about 4,047 (4,046.86) |
| Hectares | about 0.405 (1 hectare is about 2.47 acres) |
| Square chains | 10 (1 chain is 66 feet) |
| Square rods | 160 (1 rod is 16.5 feet) |
| Square miles | 1/640 (a square mile is 640 acres) |
What an Acre Looks Like
An American football field between the goal lines is 300 ft × 160 ft, or 48,000 square feet. An acre is about 90.75% of that. Add the two end zones and the field is 360 ft × 160 ft, or 57,600 square feet, which is about 1.32 acres. That makes an acre a bit more than three-quarters of the whole playing surface. People who picture the end zones tend to think an acre is bigger than it is.
Why 66 by 660?
The acre started as a farming unit, roughly the strip a team of oxen could plow in a day. Britannica describes the Anglo-Saxon acre as a strip 40 rods by 4 rods, or 660 by 66 feet. The 660 feet is a furlong ("furrow long") and the 66 feet is a chain, the length of a surveyor's measuring chain. Much American land is still divided along those numbers. A square mile holds 640 acres, a quarter of it holds 160, and a quarter of that holds 40. A square 40-acre piece is 1,320 feet on a side, exactly a quarter mile.
Common Lot Sizes in Acres
| Acres | Square feet | Square lot, each side | Square lot, perimeter |
|---|---|---|---|
| 1/8 acre | 5,445 | about 74 ft | about 295 ft |
| 1/4 acre | 10,890 | about 104 ft | about 417 ft |
| 1/2 acre | 21,780 | about 148 ft | about 590 ft |
| 1 acre | 43,560 | about 209 ft | about 835 ft |
| 2 acres | 87,120 | about 295 ft | about 1,181 ft |
| 5 acres | 217,800 | about 467 ft | about 1,867 ft |
| 10 acres | 435,600 | 660 ft | 2,640 ft (half a mile) |
| 40 acres | 1,742,400 | 1,320 ft (a quarter mile) | 5,280 ft (one mile) |
If you're pricing a fence, the last column is your starting point. It changes with the shape, as the next section shows.
The Same Acre Can Have Many Shapes
All of these are one acre:
- 208.7 ft × 208.7 ft (square), with a perimeter of about 835 ft.
- 100 ft × 435.6 ft (a long lot with 100 ft of frontage), with a perimeter of about 1,071 ft.
- 66 ft × 660 ft (a chain by a furlong, the classic survey shape), with a perimeter of 1,452 ft.
- A sidewalk strip 5 ft wide and 8,712 ft long, which is more than a mile and a half and has a perimeter of 17,434 ft.
- Any irregular shape with 43,560 square feet inside.
The shape changes how the land feels. A long, narrow acre has more fence line and less usable width than a square one. When you compare parcels, look at the outline as well as the acreage. How to Read a Parcel Map shows where to find it.
How to Convert Between Acres and Square Feet
- Acres to square feet: multiply by 43,560. Example: 2.5 acres × 43,560 = 108,900 sq ft.
- Square feet to acres: divide by 43,560. Example: 15,000 sq ft ÷ 43,560 = about 0.34 acre.
- Acres to hectares: multiply by 0.4047.
- Hectares to acres: multiply by 2.471.
For area from lot dimensions, with worked examples for rectangles, triangles and irregular shapes, see How to Calculate Acreage of a Property.
Acre, Survey Acre and Builder's Acre
Two real versions of the acre have been in U.S. use. The international acre is 43,560 square feet of international feet, exactly 4,046.8564224 square meters. The U.S. survey acre was 43,560 square feet of survey feet, about 4,046.8726 square meters. The two differ by roughly four parts per million, which is about 25 square inches on a whole acre. NIST says the survey foot has been obsolete since January 1, 2023 and should be used only for historic and legacy work, so the international version is now the standard one.
A third, informal version has no legal standing. The "builder's acre" is 40,000 square feet (200 ft × 200 ft). It's about 8% smaller than a real acre, and it has been used in real estate marketing to make the math easier. If a listing's math seems generous, check which acre it means.
What About Hills?
An acre of hillside is still 43,560 square feet of flat, horizontal area. Surveyors measure and map land as horizontal projection, so a steep 5-acre parcel doesn't get extra acres for the slope, even though you'd need more fence and more walking to cover it.
What if the Acreage You See Doesn't Match?
The acreage on a map, in a listing and on a deed can differ slightly. Some figures come from records, some are calculated from the outline, and some are rounded. Deeds often say “more or less.” See How to Check the Size of a Parcel. To measure something yourself, How to Measure Property Area and Perimeter covers the options.
Frequently Asked Questions
How many feet is an acre?
An acre isn't a length, so it has no number of feet. It's 43,560 square feet. As a square, it's about 208.7 feet by 208.7 feet.
How many acres are in a square mile?
640. A square mile is 5,280 ft × 5,280 ft, or 27,878,400 square feet.
How many acres is a football field?
The playing field between the goal lines is about 1.10 acres (48,000 sq ft). With both end zones it's about 1.32 acres (57,600 sq ft).
How many acres is 200 feet by 200 feet?
About 0.92 acre. To make a full acre at 200 feet wide, the lot would need to be 217.8 feet deep.
Common Mistakes
- Thinking an acre is a particular shape or length.
- Mixing up acres and square feet, which differ by a factor of 43,560.
- Assuming 1 acre ≈ 200 ft × 200 ft. That's only about 0.92 acre.
- Forgetting that listed acreage may include land you can't use, such as a steep slope or wetland.
Sources
- U.S. Survey Foot: Revised Unit Conversion Factors (NIST) Exact acre, chain, rod and square-mile definitions; international and survey values.
- Ending the Era of the U.S. Survey Foot (NIST) Survey foot superseded from January 1, 2023.
- Acre (Britannica) 43,560 sq ft, 4,840 sq yd, 660 × 66 ft origin.
- What is the unit called an acre? (sizes.com) Square-acre side length, perimeter by shape, horizontal measurement.
- Acre (Wikipedia) Background only: football field comparison, survey vs. international acre, builder's acre.