Did you know that almost 85 percent of women wear the wrong bra size? Wearing the wrong size can cause sagging, discomfort and stress on your back. The right bra can be flattering to your outfit, comfortable and fitting and make you feel more confident about yourself. A bra size is composed of two measurements: your band size and your cup size. The band size is important and the bra needs to fit snugly around you, not too tight but not loose. The cup size is important to prevent breast damage and to prevent spillage.