Cheapest Airlines in the USA
The cheapest airlines in the USA often have the lowest base fares but charge for bags, seats, and other add-ons. This guide covers Spirit, Frontier, Allegiant, Southwest, and how to compare total cost so you pick the best option for your trip and budget.
Spirit, Frontier, and Allegiant
Spirit, Frontier, and Allegiant are ultra-low-cost carriers (ULCCs) that offer low base fares and charge for carry-on bags, checked bags, and seat selection. If you travel with only a personal item and don’t care where you sit, you can save a lot. If you need a bag and a seat, add those fees before comparing to other airlines. Use Google Flights and Skyscanner to compare total price; see our How to Get Cheap Flight Tickets for more strategies. Plan your travel budget with our Personal Finance Planner so you know how much you can spend on airfare and add-ons.
Southwest: bags included
Southwest doesn’t charge for two checked bags or carry-on; that can make it cheaper than ULCCs when you’re traveling with luggage. Fares are often competitive on many domestic routes. Southwest doesn’t appear on Google Flights or Skyscanner—check their site directly and use our Track Flight Prices approach by checking periodically or setting a reminder.
Major carriers: when they compete
American, Delta, and United sometimes match or undercut budget airlines on popular routes, especially when they have sales or when you book in the right window. Use our Best Time to Book Flights guide and compare total cost (including bags on ULCCs) before you book. Major carriers offer more legroom and amenities, which can be worth it for long flights or business travel.
Comparing total cost
Always add bag and seat fees to budget airline fares before comparing. A $80 Spirit fare plus $50 for a carry-on and $20 for a seat is $150 total—a $140 major-carrier fare with a free carry-on may be the better deal. Use comparison tools and our travel hub guides to decide. For career-related moves, use our Salary Calculator to weigh pay in different cities so travel cost is part of your decision.
Frequently asked questions
Spirit, Frontier, and Allegiant typically offer the lowest base fares on many US routes. Southwest often has competitive prices with bags included. Compare total cost (base + bags + seats) before choosing.
Yes. US budget carriers meet the same FAA safety standards as major airlines. The main tradeoff is less legroom, fewer amenities, and à la carte fees for bags and seats.
Book early, travel light (personal item only if possible), and compare total cost including bags and seat selection. Sign up for their emails for flash sales. Use Google Flights and Skyscanner to compare with other airlines.