How Do you measure a western saddle?

I'm looking to by a western saddle for my morgan horse, and I was wondering if there is any special way you have to measure your horse?

Does it really only matter with the gullet size?

How wide would a 7 inch gullet be?

You have to make sure that the whole saddle fits your horse- yes, gullet size, but also the angle of the bars and rocker, wither clearance and spinal clearance etc. It's the same basic stuff as with an english saddle.
If you're unsure how to fit a saddle or don't have much experience, please get a saddle fitter out to help you.
Good luck!

Thanks, I know how to check the wither and spinal clearance. I was just unsure on the different gullet sizes.

Gullet width, unfortunately, doesn't mean a whole lot because there are so many other factors to consider. "Bars" will give you a general idea (narrow horses need Semi-QH, regular horses need QH, and wide horses need Full-QH), but even that is just a starting point that varies greatly between manufacturers.

Thanks, This is a photo of my horse. To me I think he has a short back.