Acreage Calculator
Calculate acreage from lot dimensions in feet, yards, chains or meters. Handles rectangles, triangles, circles and four-sided lots, plus hectares and fence perimeter.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Acreage
- 2.755 acres
- Rectangle: length x width. 1 acre = 43,560 sq ft = 10 square chains
- Area
- 120,000 sq ft
- Entered dimensions converted to feet first
- Square meters
- 11,148 m²
- 1 acre = 4,046.86 m²
- Hectares
- 1.1148 hectares
- 1 hectare = 2.4711 acres
- Perimeter
- 1,400 ft
- Boundary length for fencing, before gates and corner posts
Acreage formula
Acres = Square feet / 43,560
Rectangle = Length x Width; Triangle = Base x Height / 2
Four-sided lot = (Front width + Rear width) / 2 x Depth
1 acre = 43,560 sq ft = 4,840 sq yd = 4,046.86 m² = 10 square chainsWorked example
A pasture measured in chains off an old deed runs 12 chains deep by 7.5 chains wide. In feet that is 12 x 66 = 792 ft by 7.5 x 66 = 495 ft, so 792 x 495 = 392,040 square feet. Divide by 43,560 and the tract is 9.000 acres, which is also 12 x 7.5 = 90 square chains divided by 10.
A four-sided building lot is 240 ft deep, 90 ft at the road and 130 ft along the rear line. The average width is (90 + 130) / 2 = 110 ft, so the area is 240 x 110 = 26,400 square feet, or 0.606 acres. At $65,000 per acre that lot is $39,394 of land.
Quick reference
| Lot size | Square feet | Acres | Hectares |
|---|---|---|---|
| 50 x 100 ft | 5,000 | 0.115 | 0.0465 |
| 60 x 120 ft | 7,200 | 0.165 | 0.0669 |
| 100 x 100 ft | 10,000 | 0.230 | 0.0929 |
| 104.36 ft square (quarter acre) | 10,891 | 0.250 | 0.1012 |
| 132 x 165 ft (half acre) | 21,780 | 0.500 | 0.2023 |
| 208.71 ft square (one acre) | 43,560 | 1.000 | 0.4047 |
| 1 chain x 10 chains (66 x 660 ft) | 43,560 | 1.000 | 0.4047 |
| 295.16 ft square | 87,119 | 2.000 | 0.8094 |
| 660 x 660 ft | 435,600 | 10.000 | 4.0469 |
| 1,320 x 1,320 ft (quarter-quarter section) | 1,742,400 | 40.000 | 16.1874 |
Why a quarter acre lot is rarely square
An acre is a fixed area, not a fixed shape. A square acre is 208.71 ft on a side and a square quarter acre is 104.36 ft, but almost no platted lot looks like that. Subdivisions cut narrow, deep lots to spread the cost of the street and the utility trunk over more frontage. A typical quarter acre reads 60 x 180 ft or 75 x 145 ft. All three are 10,890 square feet. The 60 x 180 lot still needs 480 ft of fence against 417 ft for the square one, and the setbacks leave a narrower building envelope.
For an irregular parcel, break it into triangles rather than guessing an average. Pick one corner and run a line to every other corner. Each piece becomes a triangle you solve from a base and a height measured square to that base. Add the pieces. This is what the surveyor's coordinate method does, and it is exact for any straight-sided lot no matter how odd. Curves along a cul-de-sac or a creek are the exception; those get a plat, not a tape.
Chains, rods and reading the deed
The acre was defined off the chain, and the chain survives in deeds because of it. Edmund Gunter's chain is 66 ft made of 100 links, a rod is a quarter chain at 16.5 ft, and a furlong is 10 chains at 660 ft. An acre is one chain by one furlong, which is 10 square chains, 160 square rods, or 43,560 square feet. Ten square chains times 4,356 square feet per square chain is where the odd 43,560 comes from.
Two systems describe US land. In the thirteen original states plus Texas and Kentucky, deeds use metes and bounds. A call reads as a bearing such as N 45 degrees 30 minutes E and a distance in chains from a monument. Everywhere the federal government surveyed, the Public Land Survey System applies. BLM cadastral survey divides land into 6 mile square townships, 36 sections of one square mile each, and quarters down to the 40 acre quarter-quarter. A description reading NE 1/4 of the SW 1/4 is 40 acres. University of Maryland Extension FS-619 walks through following an old metes and bounds call with a compass. Only a licensed surveyor can legally set a corner.
What this calculator leaves out
This is a horizontal area from the dimensions you enter. It does not net out the road right of way, easements, wetland or floodplain, or the setbacks that shrink the building envelope. It does not check the deed against the recorded plat, resolve a gap or overlap with a neighbor, or handle curved boundary lines. Survey costs, perc tests, corner monumentation and the difference between deeded acreage and assessed acreage on the tax card are all outside the result.
Mistakes that cost money
- Reading a deed call of 10 chains as 10 feet. A chain is 66 ft, so the tract comes out 66 times short.
- Measuring along a hillside instead of level. Acreage is horizontal area, so slope distance always reads high.
- Using the tax card acreage as buildable land; it includes the road right of way, easements and any wetland.
- Clicking the tree line on an aerial tool rather than the survey pins. Fence lines and pins routinely differ by several feet.
- Treating a four-sided lot as a trapezoid when the two widths are not parallel; split it into two triangles instead.
- Quoting acreage to four decimals off a tape measurement. Only a licensed surveyor's plat settles a boundary dispute.
Key facts
- One acre is 43,560 square feet, 4,840 square yards, 4,046.86 square meters and 0.404686 hectares.
- A square acre measures 208.71 ft on a side, so a square quarter acre is 104.36 ft on a side.
- A surveyor's chain is 66 ft of 100 links, and a rod is 16.5 ft. An acre is 10 square chains or 160 square rods.
- A Public Land Survey System section is one square mile, 640 acres, and a quarter-quarter section is 40 acres.
- A quarter acre is 10,890 square feet and a half acre is 21,780 square feet.
Frequently asked questions
How many square feet are in an acre?
43,560 square feet. That is also 4,840 square yards, 4,046.86 square meters and 10 square chains.
How big is a quarter acre lot?
10,890 square feet. If it were square it would be 104.36 ft on a side, but platted quarter acre lots are usually long rectangles such as 60 x 180 ft.
What is a chain in a property deed?
A surveyor's chain is 66 ft, made of 100 links of 7.92 in each. A rod is a quarter chain at 16.5 ft. Ten square chains make one acre.
How do I find the acreage of an irregular lot?
Split it into triangles from one corner, solve each as base times height divided by two, add the square feet, then divide by 43,560. Curved lines need a surveyor's plat.
Sources and references
- NIST Handbook 44, Appendix C, General Tables of Units of Measurement (NIST)
- Cadastral Survey and the Public Land Survey System (Bureau of Land Management)
- Fact Sheet 619, How To Determine Your Property Boundaries (University of Maryland Extension)
Next steps for this project
The usual order for a measurement & cost project. See all measurement & cost calculators.
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