Circle equation calculator

Circle equation forms

Standard form: (x − h)² + (y − k)² = r² where (h,k) is center, r is radius.

General form: x² + y² + Dx + Ey + F = 0.

To convert general → standard: complete the square for both x and y terms.

Example

Center (2, 3), radius 5: (x − 2)² + (y − 3)² = 25

Expanded: x² − 4x + 4 + y² − 6y + 9 = 25 → x² + y² − 4x − 6y − 12 = 0