Thanks for reaching out! Our manufacturers /Saddlers have been building and fitting saddles for almost 60 years now, and have found that gullet measurements are not reliable for fitting saddles. There are many different ways and places that people measure the gullet width, and there is no way to make sure that a measurement is accurate. Additionally, it is not the defining factor of saddle fit. Most importantly, not every saddle with a specified gullet measurement will fit the same. The angle and twist of the bars affect how the saddle will fit. So if you not sure we suggest sending as many photos of your horse as possible and we can show you how to do a back trace ,Once i have this information i can then forward to our experts if their fields.