Kai Roloff is 191 cm.
Jeremy Roloff is about 6'1".
Matt Roloff is 4' 2" tall. (As per IMDB.COM)
Roloff de Jeu is 186 cm.
Zach Roloff is about 4 foot 2. Sources:Little People Big World
5'8 1/2
Kai Scheve is 182 cm.
Kai Schumann is 186 cm.
Kai Noll is 186 cm.
Kai Nuuhiwa is 6' 1".
Kai Soremekun is 5' 6".
Kai Shishido is 180 cm.
Kai Vasmel is 180 cm.