breast hemicircumference breast hemicircumference breast hemicircumference, also sometimes referred to as breast circumference or as breast width, is an anthropometric measure of the breasts which has been used in studies to assess breast development and breast size, including in transgender women. it is the medial horizontal length (measured with a flexible tape measure) from one side of the breast to the other side and running over the nipple. a measurement of 7 inches is said to correspond to an a cup, 8 inches to a b cup, 9 inches to a c cup, and so on, with each further 1-cm increment or decrement corresponding to one cup size up or down. measurement of breast hemicircumference.