Most airlines allow one piece of carry-on luggage with a maximum size of 22 by 14 by 9 inches, as of June 2015. Airlines also typically allow one personal item, such as a purse, briefcase or laptop.
Each airline sets its own maximum size for carry-on luggage, so certain airlines allow larger pieces. Southwest Airlines, for example, allows one piece of carry-on luggage with a maximum size of 24 by 16 by 10 inches. Airlines provide a bag sizer at the airport, which has these measurements. If a bag appears too large, the airline may require a traveler to place the bag in the bag sizer. If it fits, he may take it as a carry-on; otherwise, he must check the bag.
The maximum size for carry-on luggage usually includes any handles or wheels. Certain airlines also have size guidelines for personal items. Certain items, such as umbrellas, outer garments and food, are typically allowed by airlines and don't count as personal items. Pet carriers are allowed as a carry-on, but whether it counts as carry-on luggage or a personal item varies based on the airline.
Travelers can store carry-on items in the plane's overhead compartments or beneath the seat in front of them. If necessary, the airline can require passengers to check any carry-on luggage.