This circle equation calculator displays a standard form equation of a circle, a parametric form equation of a circle, and a general form equation of a circle given the center and radius of the circle. Formulas can be found below the calculator.

The calculator takes the equation of a circle in general form, with variables for x, y, and constants a, b, c, d and e, and converts it to the standard form equation for a circle with variables h, k, and r. It then calculates the center of the circle (h, k) and its radius r. If the equation cannot be converted to standard form, the calculator reports an error message.