In order to keep the passenger compartment uncluttered and safe, the airlines place rules and size limits on the luggage that each traveler can carry on the plane.The primary rule is the size limit stating that bags carried on board must be small enough to store below your seat or in the overhead compartment.Currently the basic rule is that carry on baggage must be no taller than 22 inches, no wider than 14 inches, and no deeper than 9 inches.In many cases, you'll also have to contend with limits on weight.n order to keep the passenger compartment uncluttered and safe, the airlines place rules and size limits on the luggage that each traveler can carry on the plane.