To measure the acreage of an irregularly shaped lot, first measure the perimeter of the entire space in question. Next, divide the property on paper into as many triangles as fit the dimensions, calculate their areas and add them together. The proper tool for such calculations is Heron's formula.
The first step, calculating the perimeter of the lot, can be the most difficult one, and may require sophisticated surveying equipment to complete. When considering dividing the resulting shape into triangles, remember that a four-sided polygon produces two triangles; a five-sided one, three. Next, name each triangle using a three-letter designation, such as ADE and EBC, with each pair of contiguous triangles sharing one letter marker.
To use Heron's formula, first recognize its appearance: the area of the triangle is equal to the square root of (S(S-a)(S-b)(S-c). In this case, A, B and C represent the lengths of each triangle side respectively, and S denotes the semiperimeter, or half of A plus B plus C. It may be easier to first designate all the measurements of the lot in feet, yards or miles, and then convert the final calculation into acres. One acre is equal to 4,3560 square feet, 4840 square yards and .0015625 square miles.