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  WEIGHT (KG)
S - EU 36 60–70cm 47–56kg
M - EU 38 70–75cm 57–63kg
L - EU 40 75–80cm 64–74kg
XL - EU 42 80–85cm 75–83kg
2XL - EU 44 85–95cm 84–99kg
3XL - EU 46 95–118cm 100-110kg