Circle Equation Calculator

Find the equation of a circle in standard form using diameter endpoints. Visualize the circle and get the equation instantly.

Enter Diameter Endpoints

Endpoint 1 X:

Endpoint 1 Y:

Endpoint 2 X:

Endpoint 2 Y:

Circle Equation:

Circle Visualization

Understanding Circle Equation

The standard form of a circle's equation is (x - h)² + (y - k)² = r², where (h, k) is the center of the circle and r is the radius. Given the endpoints of a diameter (x₁, y₁) and (x₂, y₂), the center (h, k) is the midpoint of the diameter, calculated as h = (x₁ + x₂) / 2 and k = (y₁ + y₂) / 2. The radius r is half the length of the diameter. This tool simplifies finding the circle's equation and visualizing it on a graph. Simply input the coordinates of the diameter endpoints to instantly calculate and see the circle.

For more information on circle equations, you can refer to resources like Math is Fun - Circle Equations.