How to find your bra size
Check the fit of your bra in four areas: straps, band, cups and center gore. Straps Adjustable straps allow you to continue to get your best fit as the elastic in the straps loosens due to wear. Your straps should stay in place without digging or slipping. If your straps dig or slip, you may be wearing the wrong band size. Bras with convertible straps may give you a better fit.
The band, not the straps, provides most of the support in the bra. The band should fit securely but not tightly. You should be able to fit a finger between the bra band and your body. A new bra should fit best in the loosest row of hooks, because the bra will loosen with wear. You will switch to the tighter rows of hooks over the life of the bra. The band should not ride up. If there are gaps at the bottom of the cup, the band is too loose, a sign it is time to buy a new bra.
The cups should look full and smooth, without spillage. If the cups look kind of empty, you need a smaller cup size. If you are seeing spillage on the sides or the top of the cups, you may need a larger cup size or a bra designed with more cup coverage or higher sides. If you wear an underwire bra, the underwire should be flat against your chest without pinching anywhere.
You should not be able to stick a finger under the center gore. It should lie flat against your chest. A smaller-busted woman may need to go down a size to fit well in a brand designed mainly for larger women. A large-busted woman may need to go up a size to fit well in a brand designed mainly for smaller-busted women.
A final note:
Bra size is not a constant. You probably do not wear the same bra size you wore five years ago. Many factors can affect your bra size, in addition to the brand or style you choose, including weight gain or loss, aging, exercise routine and pregnancy. We recommend you measure your bra size annually.