You’re bubbling out of the cup
This means your cup size is either too small, or you’ve chosen the wrong style for your shape. For example, full-busted women should steer clear of demi bras, and instead opt for full-coverage bras that allow for a smoother look under clothing. When trying on bras, take a few moments in the dressing room to see how they look under a shirt. If you can see an indent where the bra cuts into your chest, move up a cup size or try a different style.
The band isn’t parallel to the floor
If your bra’s back band creeps up toward your shoulders, it’s likely a size too big and not giving you the proper amount of support, which can lead to shoulder and back pain. Go down a band size.
The underwire pokes and prods
This indicates that your cup size is too small. (Experts say most women are wearing a band that’s too big and a cup that’s too small.) The underwire on your bra should come from behind your breast tissue. If it seems like it’s too narrow or digs into your skin, try on the next size.