The abdominal circumference determines the size:

Height> Size> Belly circumference
28 cm | X-small = 65-75 cm
28 cm | Small = 75-85 cm
28 cm | Medium = 56-108 cm
28 cm | Large = 95-108 cm
28 cm | X-large = 108-120 cm
28 cm | XX-Large = 120-135 cm