Abstract: A random size carton sealer for folding and gluing carton flaps is disclosed which includes an infeed conveyor; three transfer sections; three flap folding, gluing and compressing sections; and an outfeed section. The cartons to be sealed by the apparatus normally have three sets of top and bottom flaps and two minor flaps for sealing. The infeed conveyor conveys cartons onto the first transfer section. The first transfer section transfers cartons to the first flap folding, gluing and compressing section. The first flap gluing, folding and compressing section seals a first set of top and bottom flaps on a carton and then conveys the carton to the second transfer section. The second transfer section folds a first minor flap on cartons and conveys the cartons to the second flap folding, gluing and compressing section. The second flap gluing, folding and compressing section seals a second set of top and bottom flaps on a carton and then conveys the carton to the third transfer section.