I know there is probably not a solution for this issue, I love ThredUP, but I do have to say that the size "L" in one company is sometimes not nearly the same fit as a "L" from another company. I wonder if adding one or two dimensions would be helpful while the garment is lying flat. I will still continue ordering from ThreUP, but maybe I could return fewer items if I knew how consistent the sizing was for similar items.