At 4'' he's probably between 3-10, as you said and yes, he needs a lot more room. If he's being letout into your apartment, please please make sure the floor is safe! No sharp objects, no food, no 'contaminates', no ANYTHING. Tortoises are curios and will take a nibble out of wire if they think it looks yummy they are quick little things... and it can happen before you know it.