Miss Selfridge Asos blue silk-like sleeveless party Dress size 12 USA sizing

ASOS Miss Selfridge blue silk-like sleeveless party Dress with back zipper and ties Tag shows UK size 16 but this is a SIZE 12 USA (see sizing picture) Measurements taken laying flat approximately: 20” inches armpit to armpit 17” inches waist 35” inches Length 100% polyester EUC