There are ten steps to fitting a saddle properly. To evaluate the fit of a saddle on your horse, the horse must be standing squared off on level ground with his head and neck straight ahead. The saddle is evaluated without a saddle pad.
Position of the Saddle
The saddle is placed on the horse's withers and pushed back toward the tail where it will stop at the resting place dictated by the horse's conformation. It should rest behind the shoulder blade so as not to interfere with movement.
Angle of the Points
The points of the saddle tree should be parallel to the withers (or within 10 degrees). If they are not parallel to the withers, the saddle does not fit. Note: the points of the saddle tree determine the width of the saddle.
The deepest part of the seat should be in the center. The seat should be level with a straight line parallel to the ground.
Pommel to Cantle Relationship
The cantle should be higher than the pommel.
Length of the Saddle
The saddle should never go beyond the 18th thoracic vertebra, which is the vertebra corresponding to the last rib.
Gullet Width/Channel Clearance
The gullet is the open space between the panels. There should be adequate clearance over the spine and connective tissue. Stand behind the horse to look down the gullet.
You should be able to fit 2-3 fingers between the top of the horse's withers and the pommel.
The saddle should not shift excessively from side to side or from front to back.
Panel pressure and contact
Check for uneven pressure under the points and panels on both sides of the saddle.
The horse will tell you if he is comfortable by his actions and movement. The horse is the most honest indicator we have when fitting a saddle.
Panels stuffed with wool are almost universally considered superior to foam for the following reasons: 1. wool conforms to the shape of the horses back and 2. wool can be adjusted if necessary.