The best measurement is to take an existing belt you wear and measure from the fold in the leather at the buckle end to the hole you wear the belt on and use that number (to the next highest even number). If you don't have a belt you wear, you can take your pants waist size and add two inches to that number.
We determine the size of the belt by measuring from the fold in the leather at the buckle end of belt to the center hole. We start the holes at 3" from the tip and add 7 holes 3/4" apart for maximum adjustment rather than the typical 5 holes, 1" apart.
All of our belts come with snaps at the buckle to allow you to use different buckles.