ok, I found this info on the Victoria's Secret Web site, and got to measuring at home...
"Step One: Band Size
Using a soft tape-measure, measure around the ribcage directly under the bust. The tape should rest on the lower band of your bra. Be sure the tape is snug, smooth across the back and level with the front.
Add 5 to this measurement to obtain your band size. For example, if your ribcage measurement is 29" + (5) = 34" band size. If the resulting band size is an odd number like 33", you can usually go to the next even band size (34"), but you may also want to try the next lower band size (32")."
• So I measured for band size and came out with 32.5. So with the 5 added, that's 37.5, or a 38. Which is what I am now. Weird how every other part of my body is different, OTHER than that number.
"Step Two: Cup Size
Measure completely around the bust at the fullest point, holding the tape measure straight but not tight. The difference between this measurement and your BAND size is your cup size. Each inch of difference is equal to one cup size. For example, if your band size is 34" and your bust measurement is 35", you wear an "A" cup.
if the difference is:
less than 1 inch =AA
1 inch =A
2 inches =B
3 inches =C
4 inches =D
5 inches = DD"
• My measurement was a 36.5...so if I'm doing this correctly, that'd make me an A cup? or an A 1/2....almost B?
Another site put me at a 36AA!!!!
I might cry...



Go find a qualified fitter and let her help you out!
I am a bigger girl than I thought. It is a wonder I don't topple over. 
I guess my breasts are OFF the CHARTS in a BIG way! 
For me, at least after having 2 babies, it's kinda hard to measure them in their natural positions sans bra!