How do you determine what size western saddle you need?
You can determine the size of the western saddle you want by sitting on different saddles. You should be able to put your hand down flat and it should reach the top of the cantle. When you find one that fits, then that is the size you need. Go to http://horses.about.com/od/choosingandusingtack/a/westernseatfit.htm or http://www.horsesaddleshop.com/saddle-help.html#.UiJuQDbDBnM for more details.
f you are small you may want try a youth" saddle..med size..a 14"-15" size..if you are big adult..a 16"..if you are "larger" than normal..a 17"..
Are you asking about sizing for you or the horse?
If you can, the best way is to take you and your horse for a saddle fitting. That way you get one that fits you and your horse :)