Our sizes are not standard US sizes, pls follow the instruction below to choose your fit size. Only wear a bra, pull a tape across the fullest part of your bust, so you could get your bust size. If your bust is about 38.5, so you could choose a size US6 . US0: Bust- 34", US2: Bust- 35.5", US4: Bust- 37", US6: Bust- 38.5", US8: Bust- 40", US10: Bust- 41.5", US12: Bust- 42.5", US14: Bust- 44", US16: Bust- 45", US18: Bust- 46.5".