Measure around the fullest part.
Measure around the natural waistline (smallest part)

2XS
Bust: 76-80cm / 30-31.5"
Waist: 57-61cm / 22.5-24"
XS
Bust: 80-84cm / 31.5-33"
Waist: 61-65cm / 24-25.5"
S
Bust: 84-88.5cm / 33-34.5"
Waist: 65-69.5cm / 25.5-27.3"
M
Bust: 88.5-93cm / 34.5-36.5"
Waist: 69.5-74.5cm / 27.3-29.3"
L
Bust: 93-99cm / 36.5-39"
Waist: 74.5-80cm / 29.3-31.5"
XL
Bust: 99-105cm / 39-41.3"
Waist: 80-86cm / 31.5-33.8"
2XL
Bust: 105-112cm / 41.3-44"
Waist: 86-93cm / 33.8-36.6"
3XL
Bust: 112-119cm / 44-46.9"
Waist: 93-100cm / 36.6-39.4"
4XL
Bust: 119-126cm / 46.9-49.6"
Waist: 100-107cm / 39.4-42.1"
5XL
Bust: 126-133cm / 49.6-52.4"
Waist: 107-114cm / 42.1-44.9"
6XL
Bust: 133-140cm / 52.4-55.1"
Waist: 114-121cm / 44.9-47.6"
7XL
Bust: 140-147cm / 55.1-57.9"
Waist: 121-128cm / 47.6-50.4"