The Problem With Bra Sizes

An often quoted statistic is that 80% of women are wearing the wrong bra size. Is this true? And if so, why?

It may or may not be true, but the truth is it could be because the standard bra sizing system is terrible. Established almost 100 years ago, and originally only meant to go up to a D cup, bra size is designated by a number and a letter: the number is the measurement of the underband, measured in inches around rib cage plus 4 or 5 (4 if the measurement is even, 5 if it is odd). The letter represents the cup size, but here is where the biggest problem lies.

Cup Size

Cup size is based more on art than science. To find your cup size, measure around the fullest part of the breast, and subtract from that the measurement taken around the rib cage. 

If difference is 1 inch, that might equate to an A cup, if there was a 2 inch difference it might equate to a B cup. The uncertainty is because different manufacturers use slightly different systems. Some manufacturers use no difference between the measurements to be an A cup, and some manufacturers a 4 inch difference equates to an A cup.

This is why there are such high stats for women wearing the wrong size bra, because it is so difficult to establish what size you are.

So depending on the manufacturer, an A cup for one could be a C cup for another.

The letter denoting the cup is not a set volume, its describing how much the difference is between breast measurement and rib cage, which means that cup size varies depending on the band size. What this cross grading system means is that a 34A cup has the same volume as a 32B cup, and as a 30C cup. So as your underband size gets smaller, so your cup size increases, even though they are the same volume.

So cup size doesn't actually equate to volume. From a scientific basis it would make more sense if the cup itself was graded into volume.