Acres to Square Feet Converter
Convert acres to square feet — an acre is an area, never a shape.
Updated
square feet
43,560sq ft
1 ac = 43,560 sq ft
In short
How many square feet is one acre?
One acre is exactly 43,560 square feet. Multiply acres by 43,560: five acres is 217,800 sq ft and a quarter acre is 10,890. The number is a definition, descending from 160 square rods, and it fixes the area only — an acre can be any shape at all.
A square acre is about 208.71 feet a side, but nothing requires an acre to be square.
acres to square feet — quick reference
| acres (ac) | square feet (sq ft) |
|---|---|
| 0.1 ac | 4,356 sq ft |
| 0.3 ac | 10,890 sq ft |
| 0.5 ac | 21,780 sq ft |
| 1 ac | 43,560 sq ft |
| 2 ac | 87,120 sq ft |
| 5 ac | 217,800 sq ft |
| 10 ac | 435,600 sq ft |
| 40 ac | 1,742,400 sq ft |
The formula, worked line by line
One multiplication by an exact integer, and no constant to defend. The acre has been 43,560 square feet for as long as the foot and the rod have had fixed lengths, and since 1959 those have been defined against the metre rather than measured against anything.
“Forty perches in length and four in breadth — 160 square rods, and 43,560 square feet.”
The rod at 16.5 feet is the odd number underneath everything here. Four rods make a chain of 66 feet, forty make a furlong of 660, and 66 by 660 is 43,560. Every awkward figure in the imperial land system traces back to that one length.
square feet = acres x 43,560
1 rod = 16.5 ft, 4 rods = 1 chain = 66 ft
40 rods = 1 furlong = 660 ft
66 x 660 = 43,560 sq ft = 1 acre
640 acres = 1 square mile = 27,878,400 sq ft- Acres
- 5
- Times 43,560
- 217,800 sq ft
- As a square
- about 466.7 ft a side
- At 200 ft of frontage
- 1,089 ft deep
- Square feet
- 217,800
Same five acres, and the two layouts are not remotely the same property. A quarter mile of depth behind a narrow frontage is a very different proposition from a square block, in access, in servicing cost and in what can be built.
Precision, and when it matters
For conversation two decimal places on the acreage is plenty. For anything recorded, keep four: a hundredth of an acre is 436 square feet, which is a room. Deeds and plats generally carry more precision than a listing does, and the plat is the figure to trust.
The metric comparison
- 1 acre
- 4,046.8564224 sq m
- 1 hectare
- 10,000 sq m exactly
- 1 hectare in acres
- about 2.4711
- 1 acre in hectares
- about 0.4047
The hectare is a decimal unit and the acre is not, so no useful land size converts to a round number in both. Quote one or the other rather than trying to make both look tidy.
One practical consequence: international listings that give both figures have usually rounded one of them, and the rounding is rarely disclosed. If the two numbers do not reconcile to four decimal places, the acreage is the derived one and the hectare figure is the original.
How to use the acres to square feet converter
Multiply by 43,560. The factor is exact, so the conversion carries no uncertainty and needs no rounding note. The interesting part is what the answer does and does not tell you, because a raw area figure is a much weaker description of land than most people assume when they read it.
An acre fixes area and nothing else. Two one-acre parcels can be a 208-foot square and a 66-foot by 660-foot ribbon, and those are entirely different pieces of property: different frontage, different fencing cost, different building envelope, often different value. The conversion answers "how much" and is silent on "what shape".
43,560
Square feet per acre
exactly, by definition
208.71 ft
Side of a square acre
not 209
640
Acres in a square mile
one survey section
The 208.71 figure is worth carrying because the rounded 209 circulates as though it were exact. The square root of 43,560 is 208.7103, so a 209-foot square comes to 43,681 square feet — 121 over. As a whole-foot approximation 209 is perfectly reasonable; as a stated dimension of an acre it is not.
The grid is why so many rural parcels come in sizes like 10, 20, 40 and 80 acres rather than in round metric numbers or in odd surveyed shapes. Those are the halves and quarters of a section, and a legal description will often name them that way rather than giving an area at all.
- 0.25 acres
- 10,890 sq ft
- 0.5 acres
- 21,780 sq ft
- 1 acre
- 43,560 sq ft
- 5 acres
- 217,800 sq ft
- 40 acres, a quarter-quarter section
- 1,742,400 sq ft
- 640 acres, one section
- 27,878,400 sq ft
The last two are the survey grid rather than round numbers, which is why rural listings cluster on them.
Convert building area between feet and metres
If the figure you are converting is floor area rather than land, the square-metre conversion is usually the one you want next.
Open the square feet converter →Acres converted to square feet at the exact 43,560 factor, with the survey-grid sizes marked where they apply.
| Acres | Square feet | Note |
|---|---|---|
| 0.1 ac | 4,356 sq ft | |
| 0.25 ac | 10,890 sq ft | a quarter acre |
| 0.5 ac | 21,780 sq ft | a half acre |
| 1 ac | 43,560 sq ft | 208.71 ft square |
| 2 ac | 87,120 sq ft | |
| 5 ac | 217,800 sq ft | |
| 10 ac | 435,600 sq ft | |
| 20 ac | 871,200 sq ft | |
| 40 ac | 1,742,400 sq ft | a quarter-quarter section |
| 80 ac | 3,484,800 sq ft | |
| 160 ac | 6,969,600 sq ft | a quarter section |
| 320 ac | 13,939,200 sq ft | a half section |
| 640 ac | 27,878,400 sq ft | one square mile |
What an acre actually looks like
Comparisons are how people build intuition for this unit, and most of the ones in circulation are wrong. The football field is the worst offender: a standard eleven-player tackle field including both end zones is 360 by 160 feet, which is 57,600 square feet, or about 1.32 acres. An acre is roughly three quarters of it.
- As a square
- 208.71 ft x 208.71 ft
- As a chain by a furlong
- 66 ft x 660 ft
- As a suburban lot shape
- 100 ft x 435.6 ft
- As a wide frontage
- 150 ft x 290.4 ft
- Every one of these
- exactly 43,560 sq ft
Four completely different pieces of land, identical on paper. This is why frontage and depth appear separately on a plat, and why an acreage figure alone is not enough to plan anything.
For a checkable metric anchor, an acre is 4,046.8564224 square metres — just over 40 percent of a hectare. A hectare is 10,000 square metres exactly and works out at about 2.471 acres, which is why land outside the United States rarely converts to round acre figures.
Gross acres against the ground you can use
The acreage on a deed is gross area. What you can build on is smaller, sometimes dramatically so, and the difference is not visible in any conversion. Setbacks pull the buildable envelope in from every boundary. Easements for utilities, drainage or access carve out strips you own and cannot obstruct.
- Gross parcel
- 43,560 sq ft
- Perimeter setbacks
- varies by zoning district
- Utility and access easements
- owned, not buildable
- Wetland, slope or floodplain
- often excluded entirely
- What is left
- the only figure that matters
None of these deductions is a fixed percentage. They come from the local zoning code and the survey, and the only reliable source is the plat itself.
This is also where the old survey acre used to matter and no longer does. The US survey foot made a survey acre about four parts per million larger than the international one. It was deprecated at the end of 2022, so for anything measured today there is a single acre and the distinction is a legacy concern only.
Every acres value, worked out
114 common acres figures each get their own page, with the answer, the arithmetic, what rounding costs, and the nearest real-world reference point on the scale.
1 to 9 ac
Questions people ask
Sources
Where the constants and formulas on this page come from. Each line names the figure it backs.
One acre is exactly 43,560 square feet, and exactly 4,046.8564224 square metres under the international foot.
US Survey Foot — Revised Unit Conversion Factors — National Institute of Standards and Technology
Land is divided into six-mile townships and one-square-mile sections of 640 acres under the Public Land Survey System.
The Public Land Survey System (PLSS) — US Geological Survey
One hectare is exactly 10,000 square metres, and the hectare is a non-SI unit used for land area.
The International System of Units (SI), 9th edition — Bureau International des Poids et Mesures
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