When I was measured at pre op I was told my size and what size compression bra I’d have – my company supplied an Anita they are quite expensive but very good I found better than my macom as had Velcro bands so easy to open without undoing for a breather x my surgeon also advised size to get if buying another sports bra 34E ms high impact I got a few but found the plain white the comfiest x I was 32a and had 350 and got a medium macom if this helps. The macom site does advise on sizing x