text: Use a fabric measuring tape and measure around your chest under your breasts (that will be the chest measurement).  Then measure around your chest and over the breasts at the fullest part (don't pull the tape too tight or make it too loose).  Each inch difference between the chest measurement and the breast measurement is a cup size.  For example, if the first number is 34" and the second is 36", then you are a size 34B, if it's 34" and 37" you are a 34C, etc.  If the measurements are 34 and 34, you are a boy!!   Sorry, I couldn't resist...