How many square feet are in an acre?

The short answer

An acre is a unit of area, not of length, so it has no fixed shape. Any piece of land that covers 43,560 ft² is one acre, whether it is a perfect square of about 208.7 × 208.7 ft or a long strip of 66 × 660 ft. In metric terms one acre is 4,046.86 m², or 0.4047 hectares, and one hectare is 2.471 acres.

Use the acreage calculator to turn the sides of any plot into acres and hectares, or the square footage calculator for rooms and smaller areas.

Square feet in fractions of an acre

Real-estate listings and zoning codes often use fractions of an acre. Multiply 43,560 by the fraction to get square feet:

Going the other way, divide square feet by 43,560. A 7,500 ft² suburban lot is 0.17 acres; a 20,000 ft² lot is 0.46 acres; a 100,000 ft² parcel is 2.30 acres.

Why 43,560? A little history

The acre began in medieval England as the area a team of oxen could plough in one day. Ploughing in long strips was efficient because turning the team was slow, so the standard acre became one furlong (a “furrow long”, 660 ft) by one chain (66 ft). 660 × 66 = 43,560 — which is why the number looks so odd today.

The chain, 66 ft, is still the unit surveyors use in the United States Public Land Survey, and a square mile (a “section”) is exactly 640 acres. A quarter section is 160 acres, the classic homestead.

What does an acre look like?

Numbers like 43,560 are hard to picture. These comparisons help:

• An American football field without the end zones (300 × 160 ft) is 48,000 ft² — about 1.1 acres. With end zones it is about 1.32 acres.
• A standard tennis court (78 × 36 ft) is 2,808 ft², so about 15 courts fit in an acre.
• A typical new suburban lot in the US is 0.15–0.25 acres; a “half-acre lot” feels roomy for a house, garage and garden.
• A professional soccer pitch (about 105 × 68 m) is roughly 1.76 acres.
• An Olympic swimming pool (50 × 25 m) covers about 0.31 acres.

Common acre shapes

Because only the area matters, one acre can have many shapes. A few that come up in land deals:

How to calculate the acreage of a lot

For a rectangular lot, measure the frontage and the depth in feet, multiply them, and divide by 43,560. A lot 75 ft wide and 150 ft deep is 11,250 ft², or 0.258 acres.

1. Find the lot dimensions. They are on your deed, the recorded plat, or the county GIS parcel viewer. A tape or a measuring wheel works for small lots.
2. Split odd shapes into rectangles and triangles. Work out each piece (length × width, or base × height ÷ 2) and add them up.
3. Convert to acres by dividing the square feet by 43,560 — or enter the sides in the calculator, which does it for you and also gives hectares.
4. For curved or very irregular boundaries, use the survey or a mapping app that measures polygon area; hand measurements of curves are rarely accurate.

Tip: if your lot dimensions are in metres, multiply square metres by 0.000247 to get acres, or divide by 10,000 for hectares. The square meter calculator handles metric plots directly.

Acres, hectares and square metres

Most of the world measures land in hectares. One hectare is 10,000 m² — a square 100 m on each side — and equals 2.471 acres. One acre is 0.4047 ha. When you compare a listing abroad with one at home, 1 hectare ≈ 2½ acres is a good mental shortcut; for exact work use the calculators above.

Building on an acre: what fits?

An acre leaves plenty of room for a house, a long driveway, a garage, a septic field and a garden, but zoning decides what you may actually build. Many rural zones require a minimum lot of 1–5 acres for a well and septic system; suburban zones may allow four or more houses per acre. Setbacks (the distance from property lines), lot coverage limits and easements all reduce the buildable area, so check the zoning code before you buy.

Once you have a plan, our other calculators help with the materials: the concrete calculator for the slab, the gravel calculator for a driveway, and the sod calculator for the lawn.

Square feet to acres: quick reference for lots

Building lots are usually described in square feet in the city and in acres in the country. These conversions cover the sizes you see most often in listings:

A quick way to estimate in your head: 10,000 ft² is a little under a quarter acre, and 40,000 ft² is a little under one acre.

Common mistakes

• Mixing up linear feet and square feet: a fence around an acre square is about 835 ft long, but the area is 43,560 ft².
• Forgetting to convert inches: 12 ft 6 in is 12.5 ft, not 12.6 ft.
• Using the gross acreage from a listing when part of the lot is road right-of-way or wetland that you cannot use.
• Assuming an acre is a fixed square — two lots of the same acreage can have very different frontage and buildable space.