A dome is a geometrical structure that is spherical in shape and functions as the roof of a building. The surface area of a dome is often measured in square feet. Therefore to determine a dome's square footage is to calculate the amount of surface area found along the outside of the dome. To perform this calculation there is a very reliable geometrical formula.
Determine the radius of the dome. The dome's radius is the distance from the center of the dome to any point along the dome's circumference (the distance should be measured in feet).
Multiply the dome's radius by itself. For example, if you knew that the radius was 10 feet you would multiply 10 by 10 to get 100.
Multiply the result from the previous step by 6.28 (6.28 is pi multiplied by 2). Using our example from Step 2, this would give us 100 x 6.28 or 628. The result of this calculation will be the area of your dome expressed in square feet.