Enter a radius or diameter into the calculator below to determine the circumference and area of a circle.
The following two formulas are used by this calculator to determine the circumference.
C = pi * D
Where C is the circumference, pi is approximately 3.14159, and D is the diameter
C = 2 * pi * 4
Where C is the circumference, pi is approximately 3.14159, and r is the radius.
Additionally, this calculator determines the area of this circle using the following formulas.
A = pi * r^2
Where A is the area, and r is the radius
A = pi * (D/2)^2
Where A is area and D is the diameter