All of our Leather dog collars measure from the topend/center of the buckle to the first and last hole. (Paisley and Euro dog measure different see descriptions)Measure your dogs neck where you want it to sit and about how tight/loose you want it. Most of our Leather collars measure (please check description before ordering)Small - 9.5"-13"Medium 13-18"Large 19-24"We do have a few styles that have a little different sizing so check the description. Padded leather collarsSmall - 9-13"Medium 13-18"Large 18-23"XL 23-28"XXL 28-32"