An acre is 43,560 square feet, but that figure alone does not tell you how far around the parcel you would have to fence. This calculator converts between square feet, acres, and square miles, and gives you the perimeter in linear feet for any lot shape.
This page focuses on area unit conversion. If you need fencing length and road frontage from acreage instead, use Acres to Linear Feet.
About pricing on this page
This calculator is intentionally price-light. Absolute dollar figures are deliberately omitted because they vary too widely by region, brand, and installer to be useful as planning estimates. The relative-comparison tables below show how options stack up against each other — which is the durable, actionable information. For a real budget, get two or three written quotes from local suppliers and contractors after they have seen the job.
Acreage and Perimeter Calculator
Enter lot dimensions or a known area. Results give acres, square feet, and perimeter in linear feet.
Acre Conversion Formulas
An acre was historically the area a yoke of oxen could plough in a day, so it does not land on a round number in any modern unit.
1 acre = 43,560 square feet = 4,840 square yards = 4,047 square meters
1 square mile = 640 acres
Acres = Square Feet ÷ 43,560
Worked example: A lot measuring 300 × 150 ft is 45,000 square feet. 45,000 ÷ 43,560 = 1.033 acres. Its perimeter is (300 + 150) × 2 = 900 linear feet — and that perimeter, not the acreage, is what a fencing quote is built on.
Acreage to Square Feet and Perimeter
Perimeter figures assume a perfectly square parcel, which gives the minimum possible perimeter for a given acreage. Real lots almost always have a longer perimeter.
| Acreage | Square Feet | Square Side (ft) | Square Perimeter (LF) | 2:1 Perimeter (LF) | 4:1 Perimeter (LF) |
|---|---|---|---|---|---|
| 1/8 acre | 5,445 | 73.8 | 295 | 313 | 369 |
| 1/4 acre | 10,890 | 104.4 | 417 | 443 | 522 |
| 1/3 acre | 14,520 | 120.5 | 482 | 511 | 603 |
| 1/2 acre | 21,780 | 147.6 | 590 | 626 | 738 |
| 3/4 acre | 32,670 | 180.7 | 723 | 767 | 904 |
| 1 acre | 43,560 | 208.7 | 835 | 886 | 1,043 |
| 2 acres | 87,120 | 295.2 | 1,181 | 1,252 | 1,476 |
| 5 acres | 217,800 | 466.7 | 1,867 | 1,980 | 2,334 |
| 10 acres | 435,600 | 660.0 | 2,640 | 2,800 | 3,300 |
| 40 acres | 1,742,400 | 1,320.0 | 5,280 | 5,600 | 6,600 |
| 640 acres (1 sq mi) | 27,878,400 | 5,280.0 | 21,120 | 22,400 | 26,400 |
Notice how much shape matters. A 4:1 rectangular acre needs 1,043 linear feet of fence against 835 for a square acre — 25% more material for exactly the same acreage.
Acre Equivalents You Can Picture
Useful reference points when you are trying to judge whether a listing figure sounds right.
| Reference | Area | In Acres |
|---|---|---|
| American football field (incl. end zones) | 57,600 sq ft | 1.32 acres |
| Football field excluding end zones | 48,000 sq ft | 1.10 acres |
| Soccer pitch (FIFA standard) | ~78,000 sq ft | ~1.79 acres |
| Basketball court (NBA) | 4,700 sq ft | 0.108 acres |
| Tennis court (singles) | 2,808 sq ft | 0.064 acres |
| Typical suburban lot | 8,000–12,000 sq ft | 0.18–0.28 acres |
| City block (varies widely) | 80,000–160,000 sq ft | 1.8–3.7 acres |
| Walmart Supercenter footprint | ~180,000 sq ft | ~4.1 acres |
Common Acreage Mistakes
Assuming Acreage Determines Fence Length
Two parcels of identical acreage can require very different amounts of fence. A square acre has an 835 foot perimeter; the same acre shaped as a long 4:1 rectangle has a 1,043 foot perimeter. That 208 foot difference is roughly $4,000–$8,000 in fencing at typical rates. Always measure the actual boundary rather than estimating from acreage.
Using 43,000 Instead of 43,560
The exact figure is 43,560 square feet per acre. Rounding to 43,000 or 44,000 introduces a 1–1.3% error, which is negligible on a quarter acre but amounts to several thousand square feet on a forty acre parcel. Since the exact number is easy to store, there is no reason to round it in a calculation that matters.
Confusing Square Miles With Acres
One square mile contains 640 acres, not 100 or 1,000. A section in the US public land survey system is one square mile, and the familiar quarter-quarter section of 40 acres comes from dividing it twice. Mixing these up produces errors of nearly two orders of magnitude in land area calculations.
Applying Square Acreage to Irregular Parcels
Flag lots, pie-shaped cul-de-sac lots, and parcels following a creek or ridge line have perimeters far longer than their acreage suggests. For these, the only reliable approach is to walk the boundary with a measuring wheel or work from a recorded plat with bearing and distance calls. Acreage from a tax record tells you nothing about the shape.
US Public Land Survey System Reference
Acreage in much of the western United States is organised by the Public Land Survey System, which divides land into a hierarchy of squares. A few useful conversions from the PLSS, which makes land area calculations in those regions easier.
| Unit | Acres | Square Miles | Notes |
|---|---|---|---|
| Section | 640 | 1.00 | 1 mile on each side |
| Quarter section | 160 | 0.25 | Half mile on each side |
| Quarter-quarter section | 40 | 0.0625 | Quarter mile on each side |
| Township | 23,040 | 36.00 | 6 miles square, 36 sections |
The Public Land Survey System does not apply to the original 13 colonies, Texas, or Hawaii, which follow metes-and-bounds or Spanish land grants instead. In those regions, parcel data comes from county records rather than a section number.