It is fully adjustable, but it's best to choose one size up if you're unsure or between two sizes, as it can be tightened.

SIZE WAIST WEIGHT (KG)
S - EU 36 83 cm 52–62 kg
M - EU 38 86 cm 63–70 kg
L - EU 40 89 cm 71–79 kg
XL - EU 42 94 cm 80–89 kg
2XL - EU 44 99 cm 90–100 kg