Measure around your under bust and compare with the cup range below.

Brand Size Cup Under Bust (inch)
S 32C/34A/34B/34C 26.0 - 31.4
M 36A/36B/36C 27.5 - 33.0
L 38A/38B/38C 29.1 - 34.6
XL 40A/40B/40C 30.7 - 36.1

Natural silk has little stretch. Size up for the best fit.