Circle Calculator

This calculator will find either the equation of the circle from the given parameters or the center, radius, diameter, area, circumference (perimeter), eccentricity, linear eccentricity, x-intercepts, y-intercepts, domain, and range of the entered circle.

To graph a circle, visit the circle graphing calculator (choose the "Implicit" option).

Enter the information you have and skip unknown values

Enter the equation of the circle:
In any form you want: `x^2+y^2=1`, `x^2/4+y^2/4=1`, etc.
Enter the center:
( )
Enter the diameter:
Enter the radius:
Enter the circumference:
Enter the area:
Enter the point on the circle:
( )

For ellipse, see ellipse calculator.

If the calculator did not compute something or you have identified an error, or you have a suggestion/feedback, please write it in the comments below.


Your input: find the center, area, circumference (perimeter), radius, diameter, x-intercepts, and y-intercepts of the circle $$$x^{2} + y^{2}=9$$$.

Graph: to graph the circle, visit the circle graphing calculator (choose the "Implicit" option).

Center: $$$\left(0,0\right)$$$.

Radius: $$$3$$$.

Diameter: $$$6$$$.

Circumference: $$$6 \pi\approx 18.8495559215388$$$.

Area: $$$9 \pi\approx 28.2743338823081$$$.

Eccentricity: $$$0$$$.

Linear eccentricity: $$$0$$$.

x-intercepts: $$$\left(-3, 0\right),\left(3, 0\right)$$$.

y-intercepts: $$$\left(0, -3\right),\left(0, 3\right)$$$.

Domain: $$$\left[-3, 3\right]$$$.

Range: $$$\left[-3, 3\right]$$$.