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

Brand Size Cup Under Bust (inch)
S 32C/34A/34B 24.8 - 30.6
M 34C/36A/36B 26.4 - 32.2
L 36C/38A/38B 28.0 - 33.8

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