Measure her.
when you can see their nipples coming from their shirt or when their the size of your palm
There is no "best" bra size.
You can know a woman's bra size by asking her. If you do not think it is appropriate to ask her for her bra size, then her bra size is probably none of your business.
You can know a friend's bra size by asking her. If you aren't comfortable asking, then it's okay for you not to know.
34 b is the average bra size in the us 36 is the best looking size
34 b is the average bra size in the us 36 is the best looking size
You can call your girlfriend and ask for her bra size. If you aren't comfortable asking her, then buy her something that is not a bra.
Your only option is to guess the girl's bra size. If you are not buying her a bra, you don't need to know her bra size. Try to find out something that's important to her instead.
You could measure it. if there are tags on the bra that tell you, then look for it.
I doNt know the average, but I am 16 and my bra size is 34B and my girlfriends is the same ( i an a bisexual)
size 8 wow
carrie underwoods bra size is 36 a carrie underwoods bra size is 36 a