As Balletboy has already written, sizes vary even among different models from the same manufacturer. He's already given his sizing guidelines, so I'll continue:I have a 30" waist on a 5'8" 145 pound frame. In terms of sizing that means I can wear a small in the Capezio cotton/lycra dancebelt, but need a medium in their quilted model. I'm a small in Sansha, but a medium in MStevens. I've never had a GWIZ that fit me at all.
Hope this helps[/i]