The standard airline allowance typically provides for one bag or suitcase plus one personal item. Airlines give examples of a personal item as a briefcase, camera, handbag or purse, laptop computer in its own bag, a small backpack or other item not exceeding 36 inches in total dimension of height, width and length.
The allowance varies with airline. Domestic airlines are typically more lenient than international flights.
Each airline determines its own limits in size of carry-on bag allowed. A rule-of-thumb maximum size is 45 inches. This equals the total lineal measurement of height, width and depth. A few airlines allow up to as much as 55 inches. International flight limits may be much less.
A straight-box rectilinear luggage design yields the most internal volume for the greatest carrying capacity. External pouches increase a bag's dimensions without adding quality storage.
A loaded luggage carry-on weight, not exceeding 22 lbs., is accepted by most airlines. Some international airlines such as Singapore Airlines restrict weight to as little as 15 lbs. Check with the individual carriers for their own specifics.
The size restrictions for a carry-on bag, as well as the personal item, allow for a safe fit into the plane overhead compartments or under the seat directly in front of the passenger.
Items considered to be "assistive" devices, such as wheelchairs, crutches and canes, do not count against any limit on the number of pieces of carry-on bags allowed, according to a summary of the Air Carrier Access Act. Assistive devices have priority for in-cabin storage space over other passengers' items brought on board at the same airport, if the disabled passenger chooses to pre-board.
Other airline exemptions that do not count against carry-on limits include outdoor clothing such as a jacket, hat or umbrella, food or drink purchased after clearing the security checkpoint, and duty, or tax-free, merchandise.
Approved infant car seats are allowed on board when you purchase a seat for your child. The seat must be an FAA-approved child safety seat device. Collapsible strollers are exempted by certain airlines as a carry-on. Other airlines require that the stroller by checked in at the gate.
