You haven’t been fitted in years
Your bra size can fluctuate from year to year with changes in weight, muscle tone, pregnancy, and age. Get fitted in person, suggests Christina Faraj, a professional bra fitter in Beacon, New York. “There are charts that will tell you how to fit a bra, but they’re not fool proof,” she says. “It’s a very individual process.” If you can’t get fitted, start with the standard bra-size formula: 1) Measure your band size by looping a measuring tape from your back to front directly under your bust and across your rib cage. If you get an odd number, round up to the next even number to get your band size. 2) To find your cup size, measure loosely around the fullest part of your chest and subtract your band measurement from this bus measurement. The difference calculates your cup size (a one-inch difference is an A cup; a two-inch difference is a B cup, etc.).
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.