How to calculate acreage

The basic acreage formula

The conversion itself is simple:

Acres = total square feet ÷ 43,560

If you already know the parcel area in square feet, use the Square Feet to Acres Calculator. If you know acreage and want square feet instead, use Acres to Square Feet.

Calculate acres from length and width

For a rectangular or nearly rectangular parcel measured in feet:

Acres = length (ft) × width (ft) ÷ 43,560

Example: a 200 ft × 300 ft parcel contains 60,000 sq ft. Dividing 60,000 by 43,560 gives about 1.377 acres.

If your parcel is made from several rectangular sections, the Land Square Footage Calculator can total the sections before converting the result to acres.

Calculate acreage for triangles and simple shapes

Triangle

Find the square-foot area first:

Area = base × height ÷ 2

A triangle with a 200 ft base and 150 ft perpendicular height contains 15,000 sq ft. That is about 0.344 acre.

Circle

If you know the radius in feet:

Area = π × radius²

After finding square feet, divide by 43,560 to convert to acres.

Combined shapes

For a parcel made from obvious rectangles and triangles, calculate each section separately and add the square-foot areas before converting to acres.

How to calculate acreage for an irregular lot

Do not use one overall length × width formula for a parcel with angled, curved or many-sided boundaries. A bounding rectangle can include land that is not actually inside the parcel.

For irregular property, use one of these approaches:

• Map trace: outline the known parcel boundary and let the polygon area calculation handle the shape.
• Survey or plat: work from recorded dimensions or calibrate a survey image.
• Split into sections: divide the parcel into measured rectangles and triangles and total them.

For a map-based planning estimate, use the Acreage Calculator & Lot Size Map. For a survey or plat image, use the Survey / Plat Image Tool.

How to calculate acreage when you only know the address

An address by itself does not contain an acreage value. If you need the recorded parcel size, start with the deed, survey, assessor or local parcel/GIS record available for that property. If you need a planning estimate, search the property location on a map and trace the parcel boundary.

Read How Many Acres Is My Property? for the difference between recorded acreage and a map-based estimate.

Common acreage conversions

For more size references, see How Many Square Feet Are in an Acre? and the Acre Dimensions Calculator.

Accuracy: calculation vs legal acreage

A correct formula can still produce the wrong parcel acreage if the dimensions or boundary are wrong. A fence, hedge, road edge or visible mowing line may not match the legal parcel boundary. Map imagery can also be offset.

Use calculators and map traces for planning, screening and material estimates. When acreage affects title, ownership, a sale, a boundary dispute, construction or another legal decision, verify the parcel using the appropriate recorded documents and qualified professionals.

Frequently asked questions