Free Online Solve area, diameter, and circumference, circle equations. The area of a circle calculator will compute the surface of a circle using a radius or a diameter. Enter the circle area, diameter, or circumference and it will solve for the other two.
Calculate the area, circumference, radius and diameter of circles. Find A, C, r and d of a circle. Given any 1 known variable of a circle, calculate the other 3 unknowns. Circle formulas and geometric shape of a circle.
D = 2R
C = 2πR
A = πR2