Last summer my 3 year old was actually wider than the door opening by a quarter of an inch. He would go in sorta sideways and raise up on one side to fit through the door. It was interesting to watch him go in at night. He had this digging motion with his front legs and would raise one back leg to get through the doorway. Just so you know, I let this go on for about a week or so before I enlarged the door opening.