How to Calculate Irregular Area

Math can be a difficult subject for a lot of students, but finding the area of rectangle (base x height) or a square (side squared) can be quite simple. That is, until you have to find the area of an irregular shape. Although it may seem a bit confusing a first, once you understand the formula, you may find that calculating the area is just as easy as it is for any other regular shape.

• 1

  Draw an "L" shaped figure on a piece of paper. Write down the lengths of the sides that were given to you. For this example, let's say that the top base of the "L" is 12 cm, the entire left side of the "L" is 22 cm, the bottom base of the "L" is 6 cm and the small side on the right side of the "L" is 4 cm.

• 2

  Draw a line cutting the "L" into two halves. You'll see that you now have two rectangles. One rectangle has a base of 12 cm, and the other rectangle has a base of 6 cm and a height of 4 cm. But you'll need to find the height of the first rectangle before you begin. You know that the entire left side of the "L" is 22 cm and the small right side of the "L" is 4 cm. You'll use this information to find the first rectangle's height.

• 3

  Subtract 22 by 4 to find the height of the first rectangle.

  22 - 4 = 18 cm

  The height of the first rectangle is 18 cm.

• 4

  Multiply 12 x 18 using your calculator to find the area of the first rectangle.

  12 x 18 = 216 cm

• 5

  Multiply 6 x 4 using your calculator to find the area of the second rectangle.

  6 x 4 = 24 cm

• 6

  Add the two areas together to the entire area of the irregular shape.

  216 cm + 24 cm = 240 cm squared.