The permitted size of carry-on luggage varies by airline. As of October 2015, American Airlines restricts carry-on suitcases to 45 inches or 22 by 14 by 9 inches. Delta Airlines maintains the same dimensions for carry-on luggage. However, Southwest Airlines gives passengers a few extra inches, extending carry-on dimensions to 10 by 16 by 24 inches.
Carry-on dimensions include any handles and wheels. Airlines maintain that each carry-on suitcase must fit easily into the overhead compartment or under the seat. Most airlines have sample bins at the check-in counters where passengers can check to see if their suitcase meets the requirements.
Some foreign airports restrict the weight of carry-on luggage. For example, Singapore's Changi International Airport restricts carry-on luggage to 15 pounds. The Incheon International Airport in South Korea restricts carry-on bags to 22 pounds. The Beijing and Shanghai international airports both limit carry-on luggage to 22 pounds.
Although the majority of airlines permit passengers one carry-on suitcase and one personal item with them on the plane, the Transportation Security Administration restricts the contents of carry-on luggage. On domestic flights, the TSA allows only one quart-sized bag of liquids, gels, creams and pastes in the carry-on luggage. Each bottle may not exceed 3.4 ounces. The TSA also restricts razors and razor blades not in a cartridge. However, it does allow disposable razors in carry-on and checked luggage.