Can't generalise because there are women shaped like anything imaginable. My fiance has this large back, smallish boobs problem and she's got extreme trouble finding fitting bras. Also then what about me? I started out being quite buffed out and muscular, with whole lot of stuff on my back, enough time on HRT and calculators are nearly 100% correct. I must be shaped like a CIS woman then? lol.
My band size has flucutated between 40 to 36 with even some 34 bras fitting when I was slimmer. 32-36 band is average, cis female average. 38 band is slightly above but still within where like +80% of all women land.
Buffed out dude with a barrel chest can definitely have this problem. Also anybody who has upper back shaped like a triange, move the tape just a bit and the difference can be huge. I have some of this so I need to be careful when measuring to make it consistent. If men and women were shaped so much differently, then I wouldn't have a cis woman friend who even after massive weight loss keeps wearing 46 bands comfortably.
It seems that measuring and using calculators tends to get more correct when there's more boob vs. chest present. Also wide rooted breasts can make measuring strange, tape will not lie, the bust - band difference IS correct, but most bra manufacturers do not give a shit about breast shape. They make bras for average woman and that means projected and narrow boobs because they always default to what ever is easiest to get sold. Don't be fooled by bras, it is highly likely the tape is correct, calculator gets close, but a lot of bras might be wrong shape to fit in the said size. Another long post could be written about wire width, shape, height, cup depth, shape and coverage and so on. It is ridiculously complicated because standards do not exist, and they can't because we're all unique.
