Acreage Calculator
An acre is 43,560 square feet, roughly 90 percent of an American football field without the end zones. That one number settles most lot-size questions, but real parcels rarely cooperate: they come as rectangles, triangles, circles, and awkward combinations of all three, and the answer is needed in different units depending on who is asking. Buyers think in square feet, listings quote acres, and international or farm work runs in square meters and hectares.
The Acreage Calculator below handles rectangle, triangle, and circle parcels with measurements in feet, yards, or meters. It returns the area in acres plus square feet, square meters, square yards, hectares, and square miles, and it also reports the older survey units you still meet on deeds (perches, square chains, and roods), the perimeter where the shape allows it, and an optional project cost from your price per square yard, square foot, or acre.
Quick Answer
Key takeaways
- Acres = area in square feet divided by 43,560. Rectangle: length times width. Triangle: half base times height. Circle: pi times radius squared.
- One acre = 43,560 sq ft = 4,840 sq yd = 4,046.86 sq m = 0.4047 hectares. One square mile = 640 acres.
- Irregular lots are handled by splitting them into rectangles and triangles, calculating each piece, and adding the pieces together.
- For a purchase or legal decision, the surveyed area on the deed is the number that counts. This calculator is the fast check before you rely on it.
- Quick Answer
- How acreage is calculated, step by step
- Worked example: a 200 by 150 ft lot
- Common lot sizes at a glance
- Irregular parcels: split, calculate, add
- The units you will meet, including the old ones
- Perimeter and project cost: the two extras that save a second search
- What competing calculators miss
- Frequently asked questions
- Add This Calculator to Your Website
How acreage is calculated, step by step
Every acreage result follows the same two moves: find the area in square feet first, then divide by 43,560. The only thing that changes between shapes is how you get the square feet, and the calculator converts yards and meters to feet before it starts so the division is always consistent.
Measure in one unit and stick to it. Use feet, yards, or meters for every side. Mixing feet for length and meters for width is the most common source of wrong acreage, and it is why the tool asks for a single measurement unit up front.
Apply the shape formula. Rectangle: length times width. Triangle: half the base times the perpendicular height. Circle: pi times the radius squared. The United States Geological Survey explains the underlying land-measurement system in its National Map program resources, where parcel and boundary measurement sits inside the wider federal mapping framework.
Divide by 43,560. That is the definition of an acre in square feet, a figure that comes from the old English survey chain system covered below. Everything else in the result box is a conversion of that same area, not a separate calculation.
Worked example: a 200 by 150 ft lot
The calculator is pre-filled with a 200 ft by 150 ft rectangle in feet, a common large suburban or small rural lot. Here is exactly what it returns when you press Calculate Acreage, checked against its own code:
| Figure | Value |
|---|---|
| Area (200 × 150 ft) | 30,000 sq ft |
| Acres (30,000 ÷ 43,560) | 0.69 acres |
| Square meters | 2,787.09 sq m |
| Square yards | 3,333.33 sq yd |
| Hectares | 0.28 ha |
| Square miles | 0.0011 sq mi |
| Perimeter (2 × (200 + 150)) | 700 ft (213.36 m) |
| Historical units | 110.19 perches, 6.89 square chains, 2.75 roods |
Try the other shapes with the same tool to see how shape changes the answer. A triangle with a 100 ft base and an 80 ft height covers 4,000 sq ft, or 0.09 acres. A circle with a 50 ft radius covers about 7,854 sq ft, or 0.18 acres. If you are pricing ground cover for a lot this size, a sod cost per square foot calculator turns the same square footage into a material bill, and if you are building on the land, a build cost per square foot calculator applies a construction rate to the footprint.
Common lot sizes at a glance
Listings love fractions (quarter acre, half acre) and buyers rarely know what those fractions look like on the ground. This table translates the fractions people actually search for, using square lots so the dimensions are easy to picture:
| Fraction of an acre | Square feet | Square lot, ft per side | What it feels like |
|---|---|---|---|
| 1/4 acre | 10,890 | About 104 ft | A generous suburban lot |
| 1/2 acre | 21,780 | About 148 ft | Room for a house, yard, and outbuilding |
| 3/4 acre | 32,670 | About 181 ft | Large rural residential lot |
| 1 acre | 43,560 | About 209 ft | Roughly 90 percent of a football field playing area |
| 5 acres | 217,800 | About 467 ft | Small farm or hobby parcel |
| 640 acres | 27,878,400 | 5,280 ft (1 mile) | One full section in US surveying |
The bar chart makes the worked example easier to judge: at 0.69 acres it sits well above a quarter-acre lot and about two-thirds of the way to a full acre. Shape matters as much as size for cost, though. Two lots with identical acreage can have very different perimeters, and perimeter is what drives fencing, edging, and boundary costs.
Irregular parcels: split, calculate, add
Few real lots are perfect rectangles. The practical method surveyors and assessors use for an estimate is decomposition: draw the parcel, split it into rectangles and triangles you can measure, run each piece through the calculator, and add the areas. A four-sided lot with no right angles divides cleanly along a diagonal into two triangles; measure each triangle’s base and its perpendicular height, calculate both, and sum them.
Two cautions keep this honest. First, the height of a triangle must be perpendicular to the base you chose. Using a slanted side length as the height overstates the area, sometimes by a lot on a narrow, angled lot. Second, an estimate is not a survey. The Bureau of Land Management’s Cadastral Survey program is the federal authority for the original US land surveys, and its records are what legal boundary work ultimately traces back to. If money, a fence line, or a setback depends on the number, pay for a licensed survey and use the deed figure.
The units you will meet, including the old ones
Modern listings use acres, square feet, and (outside the US) hectares and square meters. The calculator shows all of them at once so you never convert by hand: 1 acre = 43,560 sq ft = 4,840 sq yd = 4,046.86 sq m = 0.4047 hectares, and 640 acres = 1 square mile. The National Institute of Standards and Technology publishes the official US conversion factors in its guide to metric unit conversions, which is the reference behind factors such as the meter to foot conversion this tool uses.
Older deeds and surveys use units from the English chain system, and this calculator is one of the few that still converts to them. A perch (or square rod) is a square 16.5 ft on a side, 272.25 sq ft, and there are 160 perches in an acre. A chain is 66 ft, so a square chain is 4,356 sq ft and there are 10 in an acre. A rood is a quarter acre, 10,890 sq ft, with 4 in an acre. The worked example lot works out to 110.19 perches, 6.89 square chains, and 2.75 roods. If an old deed describes your parcel in any of these units, you can now check the listing acreage against it directly instead of trusting a conversion you did on paper.
Perimeter and project cost: the two extras that save a second search
Area tells you how much land you have. Perimeter tells you how much boundary you have to fence, edge, or maintain, and the calculator reports it for rectangles (2 times length plus width) and circles (2 times pi times radius) in feet and meters. For triangles it deliberately does not guess: a base and a height do not determine the other two sides, so any perimeter a tool invents from those two numbers alone would be fiction. That honesty matters if you are ordering fencing.
The optional price field turns area into a project estimate in the same step. Enter a price per square yard, per square foot, or per acre and the tool multiplies it by the matching area figure. Sod at $4 per square yard on the worked example lot is 3,333.33 sq yd times $4, which is $13,333.33. The same field works for seed, gravel, paving, or a per-acre land price check: enter the asking price per acre and the total it returns is the full parcel price implied by that rate. Growers planning inputs by area can cross-check field size against the application rates in the USDA Natural Resources Conservation Service conservation planning resources, where per-acre rates for seed, lime, and fertilizer all start from an accurate acreage figure.
What competing calculators miss
We reviewed the top-ranking acreage tools before rebuilding this page. Most handle a rectangle correctly and stop there. The gaps below are the ones that send people to a second or third tool.
Winning move 1: three shapes in one tool, with honest limits. Several leading tools are rectangle-only, or handle irregular shapes by asking you to type in a square footage you already know, which assumes the answer you came for. This calculator computes rectangle, triangle, and circle areas from raw measurements, and it tells you plainly when a triangle perimeter cannot be derived instead of printing a made-up number.
Winning move 2: historical survey units alongside modern ones. None of the top tools we checked convert to perches, square chains, and roods, yet those are exactly the units on older deeds across the eastern US. If you are verifying a deed, a tool that only speaks acres and square feet leaves the hardest conversion to you. This one prints all three historical units on every result.
Winning move 3: perimeter and project cost in the same result. Competing pages treat fencing length and material cost as separate searches. Here the perimeter (for shapes where it is knowable) and an optional per-unit project cost appear with the acreage, so a sod, seed, or fencing estimate takes one calculation instead of three. A rectangular focus also misses a common trap the better guides flag: a 200 ft by 200 ft lot sounds like an acre and is not. It is 40,000 sq ft, or 0.92 acres, a full 3,560 sq ft short. Running the actual dimensions, rather than trusting a round-number guess, is the whole point of the tool.
Frequently asked questions
43,560 square feet, by definition. A square lot about 208.71 feet on each side is exactly one acre. Divide any area in square feet by 43,560 to convert it to acres.
Multiply the length by the width in feet to get square feet, then divide by 43,560. A 200 by 150 ft lot is 30,000 sq ft, and 30,000 divided by 43,560 is 0.69 acres, which is the pre-filled example in the calculator above.
About 10,890 sq ft, roughly a 100 by 109 ft lot or a square about 104 ft per side. That is a generous suburban building lot, big enough for a house, a back garden, and parking without feeling tight.
Split it into rectangles and triangles, calculate each piece, and add the areas together. A four-sided lot divides along a diagonal into two triangles. For legal purposes, rely on a professional survey and the area recorded on the deed, not an estimate.
Historical English land units still found on old deeds and surveys. One acre equals 160 perches (square rods), 10 square chains, or 4 roods. A perch is 272.25 sq ft, a square chain is 4,356 sq ft, and a rood is 10,890 sq ft.
Yes, for rectangles and circles, in feet and meters. For triangles it does not, because the base and height alone do not fix the other two sides, so any perimeter would be a guess.
Enter your price per square foot, square yard, or acre in the optional price field and the tool multiplies it by the computed area. Sod at $4 per square yard on a 200 by 150 ft lot is 3,333.33 sq yd times $4, which comes to $13,333.33.
640 acres. A section of land in US surveying is one square mile, and a township in the Public Land Survey System contains 36 sections.
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References
- U.S. Geological Survey, National Geospatial Program, “The National Map” – federal mapping program covering land, boundary, and geospatial measurement resources for the United States. USGS: The National Map. Accessed October 2026.
- Bureau of Land Management, “Cadastral Survey” – the federal program responsible for the official surveys of US public lands and the records legal boundary work traces back to. BLM: Cadastral Survey. Accessed October 2026.
- National Institute of Standards and Technology, Physical Measurement Laboratory, “Metric (SI) Unit Conversions” – official US conversion factors, including length and area conversions between customary and metric units. NIST: Metric Unit Conversions. Accessed October 2026.
- U.S. Department of Agriculture, Natural Resources Conservation Service, “Conservation Planning” – guidance on conservation planning where per-acre application rates start from an accurate field acreage. USDA NRCS: Conservation Planning. Accessed October 2026.
- U.S. Geological Survey, “National Hydrography Dataset and Land Measurement Resources” via the National Geospatial Program – background on how federal land and boundary data are measured and maintained. USGS: National Geospatial Program. Accessed October 2026.
- Bureau of Land Management, General Land Office Records – the official repository of federal land conveyance records, survey plats, and field notes for the Public Land Survey System states. BLM: General Land Office Records. Accessed October 2026.