Calculate the radius of the sphere. If you do not know the radius, the easiest way to calculate it is by first measuring the sphere around the widest part of the sphere to get the circumference. Divide the circumference by 3.14, and then by 2. For example, a sphere with a circumference of 20, divided by pi, produces a diameter of 6.36. Dividing this by 2 produces a radius of 3.18.
Raise the radius to the second power by multiplying it by itself. In this case, that would be: 3.18^2 = 10.11.
Multiply 10.11 by pi. The example produces 31.75.
Multiply 31.75 by 4. So, 31.75 x 4 produces 127. Thus, a sphere with a radius of 3.18 inches has a surface area of 127 square inches, rounded down.