An improved system and method for automatically inspecting the quality of newly-manufactured containers is disclosed that detects containers that are out-of-round by more than a predetermined amount so that they may be rejected to ensure that containers that are passed are of acceptable quality. One or more ultrasonic sensors are located at fixed positions with reference to a container that is rotated. If any sensor detects that the distance between the sensor and the container falls outside of an acceptable range, the container is rejected.