It's fully adjustable, but it's best to go one size up if you're unsure or between sizes since it can be made smaller.

SIZE WAISTLINE (CM)(INCH) WEIGHT (KG)
S 60-70 (23.62" - 27.56") 27-39
M 70-75 (27.56" - 29.53") 40-49
L 75-80 (29.53" - 31.50") 50-59
XL 80-85 (31.50" - 33.46") 60-70
XXL 85-95 (33.46" - 37.40") 69-84
XXXL 95-118 (37.40" - 46.45") 85-150