*These are rough guidelines only.  Horses can vary greatly by breed, and young horses will vary by foaling date.  To get an exact size you should measure your horse.  Using a measuring tape start at the center of the horse's chest, go around the side of the horse to the edge of the tail.  This works best if you have a helper and one of you can take each end of the tape.  Move it around to be sure you are measuring across the heaviest muscled portions of the chest and hip.