The circles overlap if the distance between the centers is less than the sum of the radii: public static boolean checkOverlap (Circle c1, Circle c2) { return Math.hypot (c1.x - c2.x, c1.y - c2.y) < c1.r + c2.r; } If you have many circles and are looking for pairwise overlaps, you might be able to use a k -d tree to do better than O (n 2).

3846