The sizes are listed in inches next to item picture.
The inch sizes are off on these. I wear a 33” waist and the medium (billed as 35-39 inches, minus 2) barely fits: it buckles only in the first and second hole and would no way fit a waist size bigger than 33. I had already returned the small because it did not even come close to fitting. Go 4” over your waist size, not 2