As of 2015, most major U.S. carriers place a limit of between 40 and 50 combined linear inches on carry-on bags, and some carriers place an additional weight limit of between 25 and 50 pounds. Carry-on luggage size and weight restrictions vary from airline to airline.
Some airlines also place size restrictions on the small personal item that each passenger is allowed to take in the cabin. These carriers limit personal item size to between 30 and 40 combined linear inches. A few carriers charge between $50 and $100 for carry-on luggage, but most carriers do not charge for it.