The cup size is calculated by the difference between the 2 measurements Out of the difference of the two measures results the cup size.

Yet the cup alone shows nothing about the size of the breasts, because the breast grows in proportion to the back underbust circumference. The m ost I i mportant measurement is the circumference of the back.

Only knowing with the circumference of the back underbust and the refore the difference in measurements, can you follow s the right bra size.