How to Calculate the Area of an Irregular Shape

Most of us can remember the arithmetic classes where we learned how to calculate the area of simple polygons like squares and triangles. While some of the things we encounter every day are those simple shapes – a dollar bill or a Dorito® – many have shapes that at first glance would seem to make it impossible to calculate their area.

Some shapes can be broken down into groups of simple shapes, and the areas of all pieces summed to a single number. Consider an L shape – one vertical and one horizontal rectangle – or an H; two vertical and one horizontal rectangle. Even a block A can be broken down to rectangles and triangles – three rectangles and six triangles. The more complex the shape, though, the more difficult it becomes to chop it into those simple polygons.

Fortunately, the mathematicians have developed a formula you can use to calculate the area of a polygon whether it’s irregular or not and independent of the number of sides. To use this formula, however, you must use the X-Y coordinates of all of the vertices. Depending on the size of the area in question, there are a couple of methods for getting those numbers.