By James Wiley
Updated Aug 30, 2022
Calculating the area of a shape is straightforward once you apply the correct formula. This guide focuses on the two most common shapes—rectangles and circles—and walks you through each step with clear examples.
Multiply the rectangle’s length by its width. For instance, a rectangle that measures 7 ft by 4 ft has an area of 28 square feet.
Divide the circle’s diameter by 2 to obtain the radius. A diameter of 20 ft yields a radius of 10 ft.
Multiply the radius by itself. In the example, 10 ft × 10 ft = 100.
Use a calculator with a π button, or substitute 3.1415 for π. Multiplying 100 by π gives an area of 314.15 square feet.
