A square foot is a unit of measurement describing the area covered by a square. This is a two dimensional measurement and is calculated by multiplying length times width. When you look at a circle, you might imagine a square with the corners snipped off and rounded and wonder how to calculate this area without the missing corners. You’ll need the number represented by pi (~3.14) and a simple equation.

Find the radius of the circle. This is the measurement from the center of a circle to any point on its perimeter. It is also half the diameter, which is the total distance across a circle.

Multiply the radius times itself (this is called “squaring” the radius).

Multiply the resulting number times pi. For example, if you have a circle with the radius of 2 feet, then the equation would be A = pi x r x r = 3.141592 x 2 feet x 2 feet = 3.141592 x 4 square feet = 12.57 square feet.