How to Use Handheld GPS Units to Measure Acreage

Get a map of the area you intend to measure and look at its shape. You can easily measure the surface area of rectangles, triangles or squares using only exterior lines, but if you have an irregular polygon, you will need to sub-divide it into something you can work with. If you do not have a map, you will need to create one.

Activate your GPS receiver and walk the outer perimeter of the area you intend to measure. Note the distance traveled for each side of the perimeter. If you need to create a map, take note of the coordinates when you reach the corners, so you can draw your own reasonably accurate perimeter map. This can be done by connecting the dots, using the length of the sides plus the corner coordinates.

Walk and measure any interior lines that need to be measured, if it proved necessary to sub-divide the area into measurable shapes.

Do the math using basic geometry. The area of a square is one side squared, or S x S. Rectangles are the width times the length, or L x W. The area of a triangle is its base times its height divided by two, or B x H / 2. If you measured a rectangle that was 500 feet wide and 866 feet long, the area would be 433,000 square feet. An acre is 43,560 square feet, so that area encompasses 9.9 acres (area divided by 43,560).

Continue working with your math if you had to sub-divide the area measured to derive figures for surface area. Add all the surface areas together to get a combined total for square feet and convert into acreage.