Acreage Calculator

Turn the measurements of a lot into acres, convert between acres, square feet, meters and hectares, or find the side you are missing.

Part 1

Shape

Length

Width

How to calculate acreage

An acre is 43,560 square feet. To find the acreage of a piece of land, measure it in feet, work out the area in square feet and divide by 43,560.

Shape	Area formula	Example
Rectangle or square	length × width	300 × 200 = 60,000 sq ft
Triangle	½ × base × height	½ × 100 × 80 = 4,000 sq ft
Trapezoid	(side 1 + side 2) ÷ 2 × height	(100 + 60) ÷ 2 × 200 = 16,000 sq ft
Circle	π × (diameter ÷ 2)²	π × 50² = 7,853.98 sq ft for a 100 ft circle

Each measurement can be in feet, inches, yards, meters, kilometers or miles, or written the way you read it off a tape, like 10'6" or 10 ft 6 in. The calculator converts everything to feet first. For a lot that is not a simple shape, press “Add another part” for each rectangle, triangle or trapezoid it can be split into. For rooms and floors, the square footage calculator is a better fit.

Example: a lot with a triangular corner

A lot has a main rectangle of 300 ft by 200 ft and a triangular corner with a base of 100 ft and a height of 80 ft. These are the same figures you get if you type them into the calculator.

Step	Operation	Result
Part 1, rectangle	300 × 200	60,000 sq ft
Part 2, triangle	½ × 100 × 80	4,000 sq ft
Total	60,000 + 4,000	64,000 sq ft
Acres	64,000 ÷ 43,560	1.4692 acres
Square meters	64,000 × 0.09290304	5,945.79 m²
Hectares	5,945.79 ÷ 10,000	0.5946 ha

How big is an acre?

One acre is a fixed area, but it can have many shapes. Its sides only have to multiply to 43,560 square feet. If you know one side and want the other, use the Find a side tab.

1 acre equals	Value
Square feet	43,560 sq ft
Square yards	4,840 sq yd
Square meters	4,046.86 m²
Hectares	0.4047 ha
Square miles	0.0015625 sq mi (1 ÷ 640)

These are some rectangles that make exactly one acre:

One side	Other side
50 ft	871.2 ft
75 ft	580.8 ft
100 ft	435.6 ft
150 ft	290.4 ft
200 ft	217.8 ft
208.71 ft (a square)	208.71 ft

Square feet to acres

Square feet	Acres
5,000	0.1148
7,500	0.1722
10,000	0.2296
20,000	0.4591
21,780	0.5
43,560	1
87,120	2

Acres to square feet, square meters and hectares

Acres	Square feet	Square meters	Hectares
¼	10,890	1,011.7	0.1012
½	21,780	2,023.4	0.2023
1	43,560	4,046.9	0.4047
2	87,120	8,093.7	0.8094
5	217,800	20,234.3	2.0234
10	435,600	40,468.6	4.0469
40	1,742,400	161,874.3	16.1874
160	6,969,600	647,497.0	64.7497
640 (1 sq mi)	27,878,400	2,589,988.1	258.9988

If the lot is a perfect square, each side is the square root of its area. A half acre is 147.58 ft on a side, one acre is 208.71 ft, two acres are 295.16 ft, five acres are 466.69 ft and ten acres are exactly 660 ft.

Where the unit values come from

The metric figures use the international foot, defined as exactly 0.3048 meters. That makes one square foot 0.09290304 square meters and one acre 43,560 × 0.09290304 = 4,046.8564 square meters. NIST lists the hectare as exactly 10,000 square meters (NIST SP 811, Appendix B.8, checked October 2026).

The same NIST table gives the acre as 4,046.873 square meters, but marks it as based on the old U.S. survey foot. NIST says the survey foot should be avoided from January 1, 2023, except for historic and legacy uses, and has been superseded by the international foot (NIST, ending the era of the U.S. survey foot, checked October 2026). This calculator uses the international foot everywhere. The difference is about 0.0004%, or roughly 0.016 square meters per acre, and it only changes the metric figures. Acres worked out from measurements in feet are the same with either foot, because an acre is 43,560 square feet of that same foot. Historic and legacy documents may still use the survey foot.

Tips for getting the number right

Keep the units straight. Mixing feet and yards changes an area ninefold, because 1 sq yd is 9 sq ft. Pick the unit next to each measurement and the calculator does the conversion.
Irregular lots. Split them into rectangles, triangles and trapezoids and add the parts. More, smaller parts follow a curved boundary more closely.
Check against your paperwork. If a survey or plat states the acreage, use that figure for anything legal and use this tool to cross-check it.
Planning materials for the land? Once you have the area in square feet, the sod, grass seed, lawn fertilizer and topsoil calculators take it from there.

Frequently asked questions

How do I calculate acreage?

Measure the length and width of the land in feet, multiply them to get square feet, then divide by 43,560. A lot that is 300 ft by 200 ft is 60,000 square feet, and 60,000 ÷ 43,560 = 1.3774 acres. For an odd shape, split it into rectangles, triangles and trapezoids, find each area and add them.

How many square feet are in an acre?

43,560 square feet. That is also 4,840 square yards, about 4,046.86 square meters or about 0.4047 hectares. A square mile holds 640 acres.

Is 200 ft by 200 ft 1 acre?

No. 200 × 200 = 40,000 square feet, and 40,000 ÷ 43,560 = 0.9183 acres, a little under an acre. To make exactly one acre with a 200 ft side, the other side has to be 43,560 ÷ 200 = 217.8 ft.

How big is a 10,000 sq ft lot in acres?

10,000 ÷ 43,560 = 0.2296 acres, a little less than a quarter of an acre. A quarter acre is 10,890 square feet.

How do I calculate the lot size of a property?

Measure each side, split the lot into simple shapes, find each area and add them up. Use rectangle = length × width, triangle = ½ × base × height and trapezoid = average of the two parallel sides × height. Then divide the total square feet by 43,560 to get acres. In this calculator, add one part for each shape and the total updates as you type.

What are the dimensions of 1 acre?

Any rectangle whose sides multiply to 43,560 square feet. For example 100 ft × 435.6 ft, 150 ft × 290.4 ft or 200 ft × 217.8 ft. If it is a perfect square, each side is 208.71 ft. Use the Find a side tab to try other widths.

How many square meters are in an acre?

4,046.86 square meters, using the international foot of exactly 0.3048 m. One acre is 43,560 square feet and one square foot is 0.09290304 square meters.