Bra size

Bra size (also known as brassiere measurement or bust size) indicates the size characteristics of a bra to accurately fit the breasts. While there are a number of bra sizing systems in use around the world, the bra sizes usually consist of a number, indicating the size of the band around the torso, and one or more letters that indicate the breast cup size. Bra cup sizes were invented in 1932 while band sizes became popular in the 1940s. For convenience, because of the impracticality of determining the size dimensions of each breast, the volume of the bra cup, or cup size, is based on the difference between band length and over-the-bust measurement.

Manufacturers try to design and manufacture bras that correctly fit the majority of wearers, while individuals try to identify correctly fitting bras among different styles and sizing systems.

The shape, size, position, symmetry, spacing, firmness, and sag of an individual's breasts vary considerably. Manufacturers' bra size labelling systems vary from country to country because no international standards exist. Even within a country, one study found that the bra size label was consistently different from the measured size. As a result of all these factors, about 25% of bra-wearers have a difficult time finding a properly fitted bra, and some choose to buy custom-made bras due to the unique shape of their breasts.