How to Figure the Cubic Yards in a Circle

Area of a Circle

• 1

  Measure the radius of the circle with a ruler.

• 2

  Square the radius. For example, if the radius equals 3 yards, multiply 3 yards by 3 yards to get 9 square yards.

• 3

  Multiply the result by pi, approximately 3.14, to find the area of a circle. Completing the example, multiply 9 square yards by 3.14 to find the area of the circle equals 28.26 square yards.

Volume of a Sphere

• 4

  Cube the radius of the sphere. To "cube" a number means to multiply it by itself, and then do it again. For example, if the radius equals 3 yards, multiply 3 yards by 3 yards to get 9 square yards, then multiply 9 square yards by 3 yards to get 27 cubic yards.

• 5

  Multiply the result by pi, approximately 3.14. In this example, multiply 27 cubic yards by 3.14 to get 84.78 cubic yards.

• 6

  Multiply the result by 4/3 to find the volume of the sphere in cubic yards. Completing the example, multiply 84.78 by 4/3 to get 113.04 cubic yards.