What size saddle is good for a 15.3hh?
The saddle size ie 16inch 17 inch etc tends to be the size that is used for the rider (size of seat) so a young kid might have a 15inch saddle and an adult a 17 inch one. The size of the saddles when it’s measurement for a horse tends to be the gullet size as in narrow,medium and wide but having said that you wouldn’t put a 17 inch saddle on a 10hh pony. Ask at your local saddlery store and they will advise on what would be the best fit for you and your horse.