Sandra has a point about the shape of breasts but I have another theory to add to the equation. I don’t think those guides for cup sizes are entirely accurate but then they are just guides, and they are designed for women.
Men’s bodies tend to taper more than women’s, ie the shoulders down to the waist is more like an inverted triangle, so if a man measures his “band size” and his “cup size” there will be a difference even without breasts (or well-defined pec’s) due to the tapering effect.
Certainly I’ve met a lot of transsexuals who swear they are a C-cup but really don’t look it, maybe they’re going by this sort of guide. According to the one Laura posted I should be an A cup, but I don’t look it, and in fact the only bra I have that fits snugly is a double-A (ie smaller).
Despite my modest size I’m happy that I’m actually “showing” now, and I do find that wearing a bra helps, as my ickle boobies are very tender still and it reduces wobbling and rubbing.
I don’t think you have to be able to hold a pencil there to benefit from wearing a bra, even though you may never lose a pencil again. Bra’s are good for your breasts, they prevent sagging, stretching of the Cooper’s ligament (I think), and even with a double-A cup, makes them look better!
The feminists may say that no woman “needs” to wear a bra, or they used to at least, I say start early, can’t hurt. If the bra fits, wear it.
xx

Gosh, it’s nearly a year since my last post on this thread…
My AA bras look a whole lot better on me now, perfectly filled out in fact. AA sounds small and it is, but to me it looks pretty good, at least I’m not totally flat-chested like I used to be. A well-fitting underwired bra now makes a big difference to my shape; so much so that I am happy to go out without any “enhancements”, though when I’m playing with my band I still like to knock ‘em dead, literally if possible…
In answer to the original question on this thread I would say the best way to determine your cup size is to buy a bra closest to the size you think you are and see how far off you are. Buy a few second-hand ones off ebay or from your local charity shop and you will get an idea of what your right size is before you splash out on something special for yourself.
There are lots of bra size calculators on the interweb, but here’s one to get you started (it works for me), note though their comment: “Measuring yourself for a bra is not an exact science, but our bra calculator can provide you with a useful starting point.”
And also, I have no idea if American bra sizes are the same, anyway here’s the link:
http://www.figleaves.com/uk/fitting_room.asp?cat=141&cm_re=fr_brafit-_-calculator-_-textlink
And by the way, sorry Wendy, but… if you can hold a pencil under your breast, you probably needed a bra years ago!
They can work wonders for even the smallest breasted women (bra’s, not pencils).
xx

Addendum:
Tape should be tight when measuring band size, but not when doing cup size.
That’s not cheating, that’s how you’re supposed to do it!
xx

Hi Rae, that’s a good point about us having a wider gap between the breasts, due to our wider frame. For a “push-in” as well as push-up bra I can recommend the Panache Atlantis Delight. A gel-filled bra (not those piddly removable gel pads) that really gives a great cleavage, even with teeny boobs like mine. I have 3, one in each colour, size 36AA, all bought off ebay.
I’m not normally a fan of Panache (their standard Atlantis range is rubbish), but the Delight delivers what it promises; it works really well.
I used to use those “magic” bra’s (invisible bra/Q-bra etc) – self-adhesive cups that pull your breasts together. Although they give a great cleavage I’ve given up using them because they are so fiddly, the silicone ones don’t stick for long and the fabric ones started giving me blisters. Plus you really need to wear breast forms over them to get a natural shape, and I prefer to go au naturel now, with a little help from my gel-bra’s of course.
Gel-filled or not though, you don’t need to be big-breasted to benefit from wearing a bra.
xx