Many vets and trainers take a special interest in saddle fitting. That said, you should be able to roughly assess saddle fit yourself.
Saddles are assessed for fit by placing the saddle on the horse’s back without a pad. The addition of pads is not a substitute for correct saddle fit. Every horse’s trunk and back are a unique combination of anatomy that must be considered when fitting a saddle. English and Western saddle tree widths are defined differently.
A saddle should not cause pain by pinching or focusing pressure in any one location. It should be symmetrical left to right. It should be level from front to back when viewed from the side.
When slid into position at the lowest part of the back, it should conform well to the withers and ribcage. There should always be at least several inches of daylight visible through the saddle at the gullet when viewed from the front.
The saddle should allow free movement of the scapula, loin and hip. It should not interfere with these areas.
Tie the horse on flat and level footing. Start by setting the saddle far forward of the correct position and slide it back into the correct position where it sits in the lowest part of the back. Check the gullet, as there should be 3-4 fingers of room there.
When viewed from the side, the saddle pommel and cantle should be level. The bars and panels of the saddle should conform well to the withers and rib cage of the horse.
Sit in the saddle and assess your fit to the saddle. There should be 3-4 fingers width between your leg and the pommel and between your rear and the cantle. Ride in the saddle and ensure it feels comfortable to you.
Tips for safety & Success
Depending on the circumstances, it may wise to contact a saddle-fit expert that can provide an educated opinion about whether or not there is a problem, and what might need to be done.