Mammogram won't tell you sizing. Bra size charts are a rough guide, but keep in mind they tend to be off quite a bit for men. Sizing will not only vary from mfg to mfg, but from bra to bra.
Agreed. If you are older when gynecomastia sets in and have a very male shape, the standard way to measure for a bra will often give you too large of a cup size. This is because on average men will have bigger chest and back muscles. According to the standard method I should be a C or D cup. but in reality the actual breast tissue just fills in an A Cup.
^^^^This.
Technically I am now a DD cup according to measurements. I am 43-1/2 on the band and 50 on the bust. (Going to 51) (inches). Technically that makes me an F cup. But barely fill a B.
Also remember that men have wider chests so the same amount of flesh that makes up a 34D on a woman though the same weight, is widely spread out on a mans chest.
Still the same amount, but doesn't protrude like a woman's.