How to Calculate Area of Irregular Shapes in Excel(2 methods)

In this article, we will learn how to calculate the area of different irregular shapes in Excel. We can follow two methods based on the criteria mentioned below:

1. If the lengths of the sides of the irregular shape are given
2. If the coordinates of the vertex of the irregular shape are given

Calculate the Area of Irregular Shapes If the Lengths of the Sides of the Irregular Shape are Given

Before jumping to the steps, you should be familiar with the following theory.

Assume you measured the length of an irregular shape’s sides as follows.

Now the complete area of the irregular shape has been divided into triangles.

Step 01: Enter the three sides of the triangle A1 in cell F4, F5, and F6 respectively 

Step 02: Enter the following formula in cell C4 to calculate the perimeter of the triangle A1

=(F4+F5+F6)/2

Step 03: Enter the following formula in cell C5 to calculate the area of the triangle A1

=SQRT(C4*(C4-F4)*(C4-F5)*(C4-F6))

Step 04: Repeat step1-3 to calculate the area of the triangle A2

Step 05: Now, Apply the following formula in cell D13 to add the area of the triangles A1 and A2

=C10+C5

Here, we calculated the total area of the irregular shape by adding the two triangles. If you need to calculate the area of a more complex irregular shape, you may divide the total area into multiple triangles

Calculate the Area of Irregular Shapes If the Coordinates of the Vertex Points of the Irregular Shape are Given

Before jumping to the steps, you should be familiar with the following theory.

Let’s assume you measured the coordinates of the shape and noted them as shown below.

Step 01: Add the coordinates to two new columns with the names X and Y. 

Note: Repeat the first coordinate in the last row of the data table and input the point counterclockwise.

Step 02: Enter the following formula in cell E8

=ABS(SUM(B5:B8*C6:C9-C5:C8*B6:B9))

Step 03: To calculate the area, Enter the following formula in cell E11

=E8*0.5

In this case, we used four points of an irregular shape. You must adjust the formula if you need to determine the area of a shape with more vertex points.