I wear size M in tops and used to buy 36A in other brands of bras, but the grip was still too tight. When I got my ThirdLove bra they still recommended the size 36A and was still too tight. When I let them know that they said I need size AA36 and they don't have it. So if you're a little heavier and have small breasts this company is not for you because apparently your breast are supposed to grow a size larger when you gain a little weight?? Right.