I'd think anything under 34 band size is normal, depending on height and whether or not the girl is barrel-chested. Sadly, many stores in the US are only carrying 34 bands in larger cup sizes (A-DDD), and 32 bands in smaller cup sizes (AA/B). So, it's even harder to tell, because a girl who measures 28"-30" inches around beneath the breasts will either have to special order and pay a crap ton or just buy a 32 band and get a smaller than we need cup size. Cup sizes are about 1" for every letter/size up, so an A cup is about 1" larger around then underboob. Blob in the story has 36" beneath her breasts (and it's probably tight), the HH is . . . I dunno, 12-14" larger around, putting her bust at 50" or so. Most shitladies are 4"+ smaller around the band, and for even large breasts, we don't measure more than 40". When I was overweight, I was a 36 band, now I have to buy 32 unless I can find a 30 somewhere.