Choosing the right size saddle pad is crucial for your horse's comfort and the effectiveness of your saddle. The saddle pad should be large enough to extend about an inch beyond the edges of the saddle on all sides. To determine the best size, you'll need to know your saddle's length and width. Typically, saddle pads are categorized by the type of saddle they are used with, such as Western or English, and by the horse's size (pony, horse, or draft). Ensure that the pad covers the horse's back adequately without hindering its movement.