It depends on the show. I believe 18 in.
how tall pony
If you are too tall for a pony, ride a horse instead.
a pony is a horse under 14.2 hands tall.
Matt Hunter is about 5'10- 5'11 feet tall
pony
Johny Hunter is 6'.
Marlon Hunter is 6'.
Hunter Emery is 6'.
Hunter Clary is 4'.
Hunter Teran is 6'.
Hunter McGilvray is 6'.
Hunter Fite is 6'.