Cup size = upper bust-lower bust
A is about10cm, b is about12.5CM, and CMC is about 15CM (and so on, the data will increase by 2.5cm with each additional cup).
Pay attention to lean forward about 45 when measuring the upper chest circumference, otherwise the value is too small and inaccurate.
Generally, the bottom bust of 68-72CM is 70\32, the bottom bust of 73-77CM is 75\34, and the bottom bust of 78-82CM is 80\36.