Acreage Calculator

A plot size is the extent of a piece of land in acres. This tool calculates the area based on the shape of the plot and converts the result to hectares, square feet, square meters, square yards and square miles.

An acre is 43,560 square feet. This can be visualized as a square with sides of about 209 feet or roughly nine-tenths the area of a football field including end zones. This conversion factor is relevant for almost any type of land area from residential to agricultural so it's worth knowing exactly what it is.

Here's how to use this calculator.

First enter the known dimensions of your property into the tool. For a rectangular lot you need length and width, for a triangular corner lot all three side lengths, and for an irregular quadrilateral you need the lengths of all four sides plus one diagonal that cuts through the lot.

Enter any measurement and select the appropriate unit. You can use feet, meters, yards or even chains. The number of acres will update in real time as you type. If you already know the area but just want to convert units, select "Convert existing area values." In this case, all conversion tables will be automatically populated with the result.

Calculate acres from length and width.

The most common shape of a lot is rectangular and the calculation for area is done in two steps. First length is multiplied by width to get the area in square feet then it is divided by 43560 which is the number of square feet per acre.

Let's take a plot of land that is 100 feet long and 150 feet wide. The area would be 15,000 square feet. Dividing this by 43,560 gives us about 0.344 acres, or just over one-third of an acre.

A piece of land that is 220 feet long by 198 feet wide has an area of exactly 43,560 square feet, which is one acre. A square plot with sides measuring 100 feet by 100 feet has an area of 10,000 square feet, or about 0.23 acres, which is just under a quarter of an acre.

Measuring irregular plots of land:

Since real plots are rarely perfectly rectangular, this tool also supports other shapes that often occur in actual surveys.

When measuring irregular plots of land surveyors usually use the option for quadrilaterals. They measure in turn the lengths of all four sides and then a diagonal that crosses through the plot. The diagonal divides the plot into two triangles whose areas can be calculated from the lengths of their three sides. By adding together the areas of both triangles, one gets the total area of the plot. This calculation gives more accurate results than a rough method which is to take the average of two opposite sides.

If the shape of your property is complex and none of the options are directly applicable, first break it up into rectangles and triangles. Then use this tool to calculate the area of each piece and add them together. If you need to subtract an area such as a pond or building, calculate that area first then subtract it from the total.

Calculating the area of a triangle with Heron's formula:

When measuring a triangular piece of land, it is usually difficult to measure the height directly, but you can always measure the length of all three sides. With these three lengths, you can use Heron's Formula to calculate the area directly.

where s is half the perimeter, or half of the triangle's circumference. So if a lot has sides of 300, 400 and 500 feet respectively, then the semiperimeter is 600. The area would therefore be the square root of 600 times 300 times 200 times 100, or 60,000 square feet, which is approximately 1.38 acres.

What is an acre?

An acre is an old unit of measurement that originated in England and originally had a practical definition: it's the area that can be ploughed by a pair of oxen in one day. It corresponds to a rectangular piece of land with a width of one "chain" and a length of one "furlong", i.e. 66 feet x 660 feet. Multiplying those two values gives us 43,560 square feet, which is ten square chains.

Thus, there is no set shape to an acre. It can be a long piece of land with one side being about 209 feet or it could be nearly square. One quarter-acre, which is common in suburban areas, is approximately 10,890 square feet while half an acre encompasses 21,780 square feet.

Acre and hectare

In most regions outside the US and UK, land area is measured in hectares. A hectare is a square with sides of length 100 meters, and has an area of 10,000 square meters.

A hectare is a relatively large unit of measure. Since one hectare is equal to approximately 2.471 acres, an acre is just over 0.4 hectares. When reading property information from other countries, you can convert hectares into acres by multiplying the number of hectares by 2.471. For example, twenty hectares would be equivalent to approximately 49.42 acres.

Conversion of area measures

Because area scales with the square of length, areas cannot be converted directly from lengths. The following table shows the exact conversion factors used by this tool.

Standard table for land areas

Fence length and perimeter

This tool will show you the perimeter of a plot of land, which is the length that goes around the boundary or in other words the length of fence required to enclose it. The amount of fencing needed depends not only on the area but also on the shape so two plots with the same area can require very different amounts of fencing.

A square one acre lot has sides of about 209 feet and will require approximately 835 feet of fence. A long thin lot with the same area of 43,560 square feet often requires thousands of feet or more of fencing. So the shape of your property is very important when you are budgeting for a fence.

Tips for calculating land area accurately:

Before checking the results, make sure all measurements are in the same units and leave the conversion to the tool. The height and radius must be measured up to their respective definitions. For example, the height of a trapezoid is the vertical distance between two parallel sides and not the length of the slanted side.

Because area increases proportionally to the square of side length, small errors in measurement are magnified in the results of area calculations. When money or legal boundaries are involved, consider the results from this tool as an estimate and have them reviewed by a professional.

This tool is for planning and general estimation purposes only and does not constitute a legal survey. It cannot be used in place of a licensed surveyor to establish property boundaries or to conduct transactions or construction work.