How to Calculate Area of a Circle

When working on a building or craft project, you may need to calculate the area of a circle. The area is the part enclosed by the circle. Overestimating the area results in excess materials while underestimating the area results in not enough materials. Learn to calculate the area before you lose time and money.

Difficulty: Easy

Instructions

1. Find the circle's diameter, which is the length of a straight line through the circle's center.

2. Divide the diameter in half. This provides you with the radius of the circle. For example, if the diameter of the circle measures 10 inches then the radius is 5 inches.

3. Square the radius of the circle, or multiply the radius by itself. For example, if the radius is 5 inches, then the radius square is 25 square inches.

4. Multiply the radius square by pi. Pi is the number 3.1416. The result is the circle's total area. If the radius is 25 square inches, the area of the circle is 78.54 square inches.