Bra Fitting - Clothing Industry Definitions presented by Apparel Search
Although there are established methods for measuring a woman for a bra, the only real way to fit a bra is by trying them on, and finding the correct size by trial and error. It is well known that many women have difficulty finding a bra to fit, and this must in part be due to a lack of understanding of how a bra works, as well as flaws in the standard measurement system.
It is a common misconception that the shoulder straps should bear the weight of the breasts, in fact the strap around the body should provide most of the support. It should be firm but comfortable. When viewed from the side, the strap that runs around the body should be horizontal and should not ride up at the back at all.
The underwires at the front should lie flat against the rib cage and should not dig in, rub or poke out at the front.
The breasts should be enclosed by the cups and there should be a smooth line where the fabric at the top of the cup ends and meets your bust. There should not be a ridge or bulging over the top or sides of the cups, even if with a 'balconette' style or lower cut shape.
You may want to visit our bra glossary.