Spirit Airlines

Spirit Airlines imposes more extra fees than any other carrier on this list, charging for carry-ons, seat selection, and even water. The airline's average bag fee of $50 per checked suitcase is 30% higher than the industry average, and its seat pitch of 28 inches is the tightest among U.S. carriers. With a 2023 complaint rate of 12.7 per 100,000 passengers—more than triple the average of the top 10 U.S. airlines—Spirit's business model proves that rock-bottom fares come with rock-bottom everything else.