Your cup size is the difference between your chest and band measurement. Step 1: Measure the fullest part of your chest. Step 2: Measure the top of your rib cage, just beneath your bust. Step 3: Subtract your band measurement from your bust measurement. Step 4: Match your number to a cup size. For example, 0=AA, 1=A, 2=B, 3=C, and on. Check out our blog post What Does the Letter Mean? Bra Sizes Explained for more information about cup size.
