By trying saddles. You can't ever say, my horse takes a 6.5" gullet in full QH bars, or whatever. Because saddles aren't standardized. A 6.5 might fit a horse perfectly with one, and a 7 or 8 in a different brand is too tight due to shape of the tree--bar angle, twist and flare, rock, etc.
Well I'm definitely NOT an expert, but a Werth fitting saddle will sit level on the horse's back. There will be ideally 3 fingers of space between the horse's withers and the inside if the swell. When you run your hand under the bars of the saddle, there should not be any places where the tree isn't touching or where it's pinching so tight That you can't get your hand under it. Saddle fitting is hard! When in doubt I have posted pictures on here and people have been really helpful with pointing me in the right direction and getting me in touch with professionals that REALLY know what they're doing.
saddle fit
