Question: what is the difference between bra size b c d?
Answer: The combination of BCD and Rib Cage is your pattern size. For example, the BCD might be 4.0 and the Rib Cage of 32. In my BCD system, you would be a 4.0/32. The BCD size increases by 1/4″ (6 mm) per size so if you happen to make a bra cup that is too small, you simply go up to the next BCD size.