• Measure around your ribcage, directly under the bust.
• Add 5 to this measurement to obtain your band size. (i.e.: If your ribcage measurement is 29" + (5) = 34" band size.)
CUP SIZE
• Measure completely around the bust at the fullest point.
• Each inch of difference between this measurement and your BAND size = cup size. (i.e.: If your band size is 34" and your bust measurement is 35", you wear an "A" cup.)
If the difference is:
less than 1 inch = AA cup     3 inches = C cup
1 inch = A cup                     4 inches = D cup
2 inches = B cup                     5 inches = DD cup