I know its frustrating. Even at the same stores it varies. Like at old navy I"m a size 6 in jeans and I can almost wear a 2 in shorts. At Express I'm like an 8 in thier jeans but at NY&Co I bought a size 2 dress. I put myself at 4/6. I think my problem is my waist is small but I have thicker legs and a big butt, sucks.