All airlines are required to adhere to rules established by the Transportation Security Administration (TSA) regarding prohibited items. These items are not allowed in carry-on baggage under any circumstances. For example, knives, box cutters, firearms and explosives are not permitted in carry-on bags. While most of the list is common sense, some everyday items, such as knitting needles, are prohibited as well. Some items can be stowed in checked baggage, so check the list thoroughly before packing.
All airlines restrict the size of hand luggage based on height, weight and depth. While measurements do vary, most airlines are within a few inches of one another. Delta Airlines and United Airlines, for example, require that the dimensions of a carry-on bag not exceed 22 by 14 by 9 inches.
British Airways' hand luggage rules are a bit more generous and state that a bag cannot exceed dimensions of 22 by 18 by 10 inches. It's best to check with the airline and measure bags before heading to the airport to avoid unpleasant surprises at the gate.
Even if hand luggage fits neatly under the seat or in an overhead compartment, airlines may still restrict the bag based on weight requirements. Guidelines vary on this within each airline. Most carriers either require the overweight bags to be checked or charge an extra fee for it.
Airlines based in the United States typically allow a maximum weight of 40 pounds for hand luggage. International carriers are often stricter, as Air Canada allows only a 22-pound maximum weight for hand luggage, and Icelandair allows a meager 13-pound bag.
