Airline Baggage Rules Southwest among U.S. carriers, allowing passengers to check two bags free of charge. Each checked bag must not exceed 50 pounds and 62 inches in total dimensions. Additionally, passengers can bring one carry-on bag and one personal item onboard without extra fees. The carry-on bag must fit in the overhead bin (maximum size 10 x 16 x 24 inches), while the personal item must fit under the seat (maximum size 18.5 x 8.5 x 13.5 inches). This policy makes Southwest a popular choice for budget-conscious travelers.