HIPSI BELT SIZE CHART:

XS/S       0-4 
M           6-10 
L          12-16 
XL        18-22
XXL         24+

All belts are adjustable on the inside of the strap. The adjustable lengths of the belts in inches are as follows:
XS/S      26"-33"
M           30"-37"
L            34"-42"
XL          39"-45"
2XL        41"-48"

Strap Width: 1.25"

hipsi recommends you select the smallest size you typically wear.