I'm a 18/20 and ordered a xl and a xxl. The XL fit nice. Mind u, I'm a 36C and not trying to hide my size. But it's not skin tight either. I normally wear a Target XXX or 1X in their plus department. The XXL was too wide in the shoulder area for me but if maybe I was bigger on top I'd kept it. I'll try to remember to update after washing.