I found this on Maidenforms website. I am going to order it and then update my review but I thought I would post this first so customers can see the size chart:
Size /  Corresponding Bra Size
 2  =  34A, 32B
 3  =  36A, 34B, 32C
 4  =  38A, 36B, 34C, 32D
 5  =  38B, 36C, 34D
 6  =  38C, 36D

Update: OK bra - the back strap is optional but on me it's about 1.5" too big adjusted on it's tightest setting. Haven't tried the tape option yet but I will update when I do. The cups fit great (I'm 32 C and bought the size 3) just the band is a bit too big.

UPDATE: Adhesive did NOT stick for more than 30 minutes in the heat. I put the bra on and started doing my makeup and both sides fell off before I was done! I barely even moved :( It was over 90 degrees but I didn't feel like I was sweating so I wouldn't trust this in cooler weather either. I don't recommend this bra unfortunately