Measure a current belt you wear from the FAR end of the buckle to the hole you use most often (to the nearest inch). This is the number to order (to the nearest inch). This will PROBABLY be about two to four inches larger than your waist or pants size. This is the size that will be custom made for you.
Leather is a natural product with unique characteristics that differ from hide to hide. Due to these differences, shade and color variations are to be expected with each belt. A brown belt you order now may not be the exact same shade of brown as a belt you may order a few months from now. This is not a fault or flaw in the leather, only an assurance that genuine natural top-grain leather is used on all belts.