Acreage Calculator

What the acreage calculator does

Land is bought, sold, and talked about in acres, but you measure a plot in feet or meters, so the two need connecting. This does that. You give it the length and width of a piece of land, and it returns the size in acres, along with hectares, square feet, square meters, square miles, square kilometers, and the perimeter.

It turns the dimensions of a plot into the unit the deed uses. Below is how it works and what an acre really comes to.

How to use it

1. Enter the length and width of the plot, each with its unit.
2. Press Calculate for the area in acres and the other units, or Reset to clear it.

For a plot that is not a simple rectangle, measure it in rectangular sections, run each through, and add the acreages.

How the acreage is worked out

It starts with the area, length times width, and then expresses that one area in every unit land is measured in:

Area = length × width, then converted to acres and the rest

The calculator works the area out in square meters internally, then converts it to acres, hectares, and the others, so you get the same plot stated every common way at once. It also works out the perimeter, the distance around the edge.

How big an acre actually is

An acre is a fixed area, but an awkward number to picture, because it is not a tidy square. One acre is 43,560 square feet, which is roughly a square about 209 feet on a side, or close to the size of a standard sports field. It is a historical unit, once the area a team could plough in a day, which is why it does not divide cleanly into feet.

That oddness is exactly why a calculator helps. A plot of a given size in feet rarely comes to a round number of acres, and the conversion is not one most people carry in their head, so turning the dimensions straight into acres saves both the arithmetic and the chance of a slip.

The other units, and the perimeter

The extra units cover whoever you are dealing with. Hectares are the metric equivalent of the acre, used for land almost everywhere outside the United States, with one hectare being about two and a half acres. Square miles and square kilometers suit large parcels, and square feet and meters suit small ones, so the same plot reads sensibly whether it is a building lot or a farm.

The perimeter is a practical extra. The distance around a plot is what you need for fencing it, walling it, or working out a boundary, so having it alongside the area means one measurement of length and width answers both how much land there is and how far it is around.

A worked example: a 200 by 300 ft lot

Say a lot is 200 feet by 300 feet.

The area is 60,000 square feet. Divided by the 43,560 square feet in an acre, that is about 1.38 acres, or roughly 0.56 hectares. The perimeter, the distance around it, is 2 × (200 + 300) = 1,000 feet.

So a lot that sounds substantial in feet comes to under one and a half acres, which is the kind of figure the acre conversion makes clear.

Questions people ask

How do I calculate acreage?

Multiply the length and width for the area, then divide by 43,560 square feet, the size of an acre. A 200 by 300 foot lot is about 1.38 acres.

How big is an acre?

43,560 square feet, roughly a square 209 feet on a side, or about the size of a standard sports field.

How many acres are in a hectare?

About 2.47, since a hectare is 10,000 square meters and an acre is a good deal smaller.

How do I measure an irregular plot?

Split it into rectangular sections, work out each one's area, and add the acreages together.

References

A quick note on the numbers. The area is plain geometry, length times width. The conversions, including that an acre is 43,560 square feet and a hectare is 10,000 square meters, follow the US National Institute of Standards and Technology guide.

1. National Institute of Standards and Technology (NIST), Special Publication 811, Guide for the Use of the International System of Units (SI). https://www.nist.gov/pml/special-publication-811