There are exactly 43,560 square feet in one acre. That equals 4,840 square yards or 4,046.86 square meters (about 0.405 hectares). If the acre is a perfect square, each side is about 208.7 feet. To turn any lot into acres, divide its square footage by 43,560.
You are looking at a land listing, a survey or a property tax bill, and you want to know how many square feet in an acre so the numbers make sense. The answer is exactly 43,560, and it has been that number for centuries.
This guide shows where that odd number comes from, how big an acre looks on the ground, a chart for common fractions like a quarter acre, the metric values, and how to work out the acreage of a lot from its dimensions. For a quick conversion, the acres to square feet converter does the math for you.
How Many Square Feet Are in an Acre?
One acre is exactly 43,560 square feet. That is a defined value in US customary units, not a rounded estimate, so you can use it for any calculation.
Acres = square feet ÷ 43,560
Square yards = acres × 4,840
| 1 acre equals | Value | Status |
|---|---|---|
| Square feet | 43,560 | exact |
| Square yards | 4,840 | exact (43,560 divided by 9) |
| Square meters | 4,046.8564224 | exact, international foot |
| Hectares | 0.40468564224 | exact (1 hectare = 10,000 square meters) |
| Square chains | 10 | exact (1 chain = 66 feet) |
| Square miles | 1/640 (0.0015625) | exact (640 acres in a square mile) |
Values from NIST’s revised unit conversion factors, which use the international foot of exactly 0.3048 meter.
Two quick checks are handy. Half an acre is 21,780 square feet, and a lot of 10,000 square feet is about 0.23 acres. If a listing says 0.25 acres, you are looking at 10,890 square feet of land.
Why Is an Acre 43,560 Square Feet?
An acre is 43,560 square feet because it was defined as a strip of land 1 chain wide and 1 furlong long, and those old survey units work out to 66 feet by 660 feet.
1 furlong = 10 chains = 660 feet
1 acre = 66 ft × 660 ft = 43,560 square feet
The long, narrow shape fit farming in strips, where a furrow ran the length of a furlong. Surveyors in the United States used a 66 foot measuring chain for public land surveys, which is why the acre fits so neatly into US land records. NIST still lists the acre as 10 square chains, and 640 acres make one square mile.
The number looks strange only because we measure in feet today. In chains, it is simple: 1 chain by 10 chains is 10 square chains.
How Big Is an Acre in Feet?
If an acre is a perfect square, each side is about 208.7 feet long, because the square root of 43,560 is 208.71. But an acre can be any shape, as long as the area adds up to 43,560 square feet.
| Width | Length | What it looks like |
|---|---|---|
| 66 ft | 660 ft | 1 chain by 1 furlong, the original shape |
| 100 ft | 435.6 ft | a long, narrow lot |
| 150 ft | 290.4 ft | a deep suburban lot |
| 200 ft | 217.8 ft | close to square |
| 208.71 ft | 208.71 ft | a perfect square |
Width times length equals 43,560 square feet in every row. Lengths are rounded to one decimal.
A useful real world comparison is an American football field. The NFL rulebook sets the field at 360 feet long and 160 feet wide, which includes both end zones. That is 57,600 square feet, or about 1.32 acres. Without the end zones (300 by 160 feet), the playing field is 48,000 square feet, about 1.10 acres. So an acre is a bit smaller than the field from goal line to goal line.
How Many Square Feet Are in Half an Acre and Other Fractions?
Half an acre is 21,780 square feet, a quarter acre is 10,890 square feet, and a third of an acre is 14,520 square feet. The chart below covers the sizes you see most in listings.
| Acreage | Square feet | Square meters | Side of a square lot |
|---|---|---|---|
| 1/8 acre | 5,445 | 505.9 | 73.8 ft |
| 1/4 acre | 10,890 | 1,011.7 | 104.4 ft |
| 1/3 acre | 14,520 | 1,349.0 | 120.5 ft |
| 1/2 acre | 21,780 | 2,023.4 | 147.6 ft |
| 3/4 acre | 32,670 | 3,035.1 | 180.7 ft |
| 1 acre | 43,560 | 4,046.9 | 208.7 ft |
| 2 acres | 87,120 | 8,093.7 | 295.2 ft |
| 5 acres | 217,800 | 20,234.3 | 466.7 ft |
| 10 acres | 435,600 | 40,468.6 | 660.0 ft |
Square meters use 1 square foot = 0.09290304 square meter exactly. The last column is the side of the lot if it were a perfect square.
Notice the side length does not grow as fast as the area. Ten acres is 10 times the land of one acre, but a square 10 acre parcel is only about 3.2 times as wide (660 feet versus 208.7 feet). That is why a 10 acre tract can look smaller than people expect from the road.
If you are planning a garden, a patio or a driveway on part of the lot, the square footage calculator handles the smaller areas.
How Many Square Meters Are in an Acre?
One acre is exactly 4,046.8564224 square meters, which is about 0.4047 hectares. Going the other way, one hectare is about 2.471 acres.
That exact metric value depends on which foot you use. Since 1959 the international foot has been exactly 0.3048 meter. For land surveying, though, the United States kept an older US survey foot, which is about 2 parts per million longer. NIST and the National Geodetic Survey retired the US survey foot at the end of 2022, and from January 1, 2023 the international foot applies to all uses, with older records kept as legacy data.
What that means for you: almost nothing. An acre based on the old survey foot was about 4,046.8726 square meters, only 0.016 square meters (about 25 square inches) larger. Across a full square mile, the gap is about 10 square meters. It matters to surveyors working with big coordinate systems, not to homeowners. The 43,560 square feet figure did not change at all.
If you work in metric, use the square feet to square meters converter for areas, the square meter calculator for measuring a plot in meters, and the feet to meters converter for side lengths.
How Do You Find the Acreage of a Lot From Its Dimensions?
To find the acreage of a lot, work out its area in square feet from the measured sides, then divide by 43,560. For a rectangle, that is width times depth divided by 43,560.
Rectangular lot: A lot 100 feet wide and 150 feet deep is 100 × 150 = 15,000 square feet. Divide by 43,560 and you get 0.344 acres, a little over a third of an acre.
Many lots are not rectangles. A common shape is a lot that is wider at the street than at the back, with straight sides that meet the back line at right angles. That is a trapezoid, and you average the two parallel sides.
A lot is 120 feet wide at the street, 90 feet wide at the back, and 200 feet deep, measured straight back from the street. How many acres is it?
- Average the two parallel sides: (120 + 90) ÷ 2 = 105 feet.
- Multiply by the depth: 105 × 200 = 21,000 square feet.
- Divide by 43,560: 21,000 ÷ 43,560 = 0.482 acres.
- Check in metric: 21,000 × 0.09290304 = 1,951 square meters.
Answer: the lot is about 0.48 acres, just under half an acre (21,780 square feet).
For odd shapes, split the lot into rectangles and right triangles, find each area, and add them. A right triangle is half of base times height. If you need help with L shapes and other room style layouts, our guide on how to calculate square footage walks through them.
Edge cases most people miss
- Depth must be straight back. If a side line runs at an angle, its length is longer than the true depth. Use the perpendicular distance, or the average formula will overstate the area.
- Slopes do not add land. Lot area is measured flat, as on a map. A hillside lot has the same acreage as a flat lot with the same boundary.
- Your survey wins. Deeds and plats list the legal acreage. Tape measurements from fences or curbs are a rough check, since fences often sit off the true line.
- Watch your units. Mixing feet and yards, or feet and meters, is the most common math error. Convert every side to feet before you multiply.
Once you have the square footage, the acres to square feet converter works in both directions, so you can confirm the acreage in one step.
Quick Recap
- One acre is exactly 43,560 square feet, or 4,840 square yards.
- It comes from 1 chain by 1 furlong: 66 feet × 660 feet.
- A square acre is about 208.7 feet on each side.
- One acre is exactly 4,046.8564224 square meters, about 0.405 hectares.
- To get acreage, divide a lot’s square footage by 43,560.
Frequently Asked Questions
How many square feet are in a quarter acre?
A quarter acre is 10,890 square feet. That is 43,560 divided by 4. In metric it is about 1,011.7 square meters, and as a square it would be about 104.4 feet on each side.
How many square feet are in half an acre?
Half an acre is 21,780 square feet, or about 2,023.4 square meters. A square half acre lot would measure about 147.6 feet on each side, though most half acre lots are longer than they are wide.
How many acres is 10,000 square feet?
10,000 square feet is about 0.23 acres. Divide 10,000 by 43,560 to get 0.2296. That is a little less than a quarter acre, which is 10,890 square feet.
Is an acre bigger than a football field?
No. An American football field including both end zones is 360 by 160 feet, or 57,600 square feet, about 1.32 acres. Without the end zones it is 48,000 square feet, about 1.10 acres, so an acre is slightly smaller than either.
How many acres are in a hectare?
One hectare is about 2.471 acres. A hectare is 10,000 square meters, and one acre is exactly 4,046.8564224 square meters, so 10,000 divided by 4,046.8564224 gives 2.471.
Did the US survey foot change the size of an acre?
Not in a way you would notice. The acre is still 43,560 square feet. Since NIST retired the survey foot after 2022, the acre is 4,046.8564224 square meters, about 25 square inches smaller than the old survey based value.
What are the dimensions of one acre?
An acre has no fixed dimensions, only a fixed area of 43,560 square feet. A square acre is about 208.7 by 208.7 feet. The original acre was 66 by 660 feet, and 100 by 435.6 feet also works.
Sources
- NIST: U.S. Survey Foot, Revised Unit Conversion Factors, acre = 43,560 ft² = 10 ch², 4,046.8564224 m² exact; chain and furlong lengths
- NIST: U.S. Survey Foot, survey foot retired after December 31, 2022; international foot = 0.3048 m exactly
- NFL Football Operations: NFL Rulebook, field is 360 by 160 feet, end zones 10 yards deep