Posted by luvbrace: 
What do you mean?  it clearly says to ad 4 or 5" on the under-bust measurement and then compare it to the bust-top measurement, and there's a chart below for figuring out the cup size according to that. 

I'm not sure how your results became 34A or 34D as that's a pretty big difference, though... try the other link that XtremeArtists posted, my results were the same, 30D.

It actually doesn't say anythign about comparing the two measurements, nor does it sya if that should be the you're comparing the underbust measurement with or without the 5 inches added.  It's not at all clear. My results actually come out differently with every formula.  The link extreme artists posted gives me the correct size.  I measure 33B, so I wear 32B or 34B, depending on the cut.