*breaths deeply*
The size of a bra is commonly described by two values: the band size (a number based on the circumference of the chest at the bust, excluding the breasts), and the cup size (given by a letter, and relating to the volume of the breasts themselves). The size of women's breasts is often expressed in terms of bra size.
Bras are commonly available in cup sizes A-DD, and one generally has to go to a specialist lingerie store to find larger cup size bras. The sizing of cup sizes can be confusing, since some manufacturers use multiple letters such as AAA or FF. A common cup size system amongst European manufacturers, in order of increasing size, is: AAA-AA-A-B-C-D-DD-E-F-FF-G-GG-H-J. It is important to note that the actual size of bra cups vary with band size. As an example, the cup in a 34B is smaller than the cup used in a 38B.
Any system for determining bra size is not without its problems, and the only real way to get the right size is by trial and error or more effectively to visit a certified bra-fitting specialist, usually found in better quality stores. Unfortunately, as is the case with most clothing, not all bras are made alike. Women find that different manufacturers' bras fit differently. However, there are several methods which may be used to provide an approximate size by measuring alone. Bra sizing systems differ widely between countries, and also between companies. Some countries use the metric measurement system rather than the Imperial system used in the UK and U.S, Australia uses dress size instead of band size.
Band size is usually determined by measuring body circumference under the breasts and then adding a specified amount to account for the fact that the ribcage is generally wider at the height of the breasts than at the point one measures at. An alternative method to determine band size involves measuring under the arms and across the top of the breasts. In the United States, various manufacturers and boutiques recommend adding different numbers to the measured circumference to determine band size, generally from 4 to 6 inches. A further complication is that some manufacturers say that when the under the bust measurement is 35" (89 cm) or more, only 3" (7.5 cm) should be added to determine the band size. Still others, particularly stores that specialize in specialty sizes, do not recommend adding anything to the size, as the band is meant to fit around the area measured, not higher.
The cup size is worked out from the difference between the band size and a measurement of the chest circumference over the fullest part of the breasts. A common, though not universal, method suggested by many manufacturers is that a difference of 1" (2.5 cm) requires an A cup size; 2" (5 cm) a B cup, and so on.
