Measure your bust around the largest part of your chest and your waist around the slimmest part of your waist.

Size Bust (in) Waist (in)
XS 31-34.5 26 - 28
S 34.5 - 37 28 - 30
M 37 - 39 30 - 32
L 39 - 42 32 - 35
XL 42 - 45 35 - 38
2X 45 - 48 38 - 41
3X 48 - 51  41 - 44