A $39 ticket sounds like a deal until bags, seat selection and boarding fees turn it into a $140 trip. That is the trick with budget airlines in the US: the base fare is only the starting price. What matters is the all-in cost — fare plus bags, seats and any change fees — against what a regular airline would charge for the same trip.
The landscape has shifted, too. Southwest ended free checked bags in May 2025 and started rolling out assigned seating in 2026. Spirit, long the cheapest base fare in the country, stopped operating in May 2026 after its second bankruptcy. Here is how the remaining options stack up in 2026.
1. Frontier Airlines — Lowest Base Fares
Frontier is the cheapest US airline by the most useful measure: average revenue per seat mile, which counts the base fare plus the extras passengers actually pay. Base fares on short domestic routes often start under $50, with sales in the $29–$49 range.
Almost everything costs extra. A carry-on typically runs $59–$99 and a first checked bag $55–$99, depending on route and timing — airport prices are the highest, so add bags during booking. Seat selection starts around $17. Frontier suits light packers on short trips. If you need a carry-on and a checked bag, do the full math first: the total can pass what Southwest or JetBlue charge for the same trip.
Best for: the lowest base fare, short hops, and travelers who pack light.
2. Allegiant Air — Best for Nonstop Leisure Trips
Allegiant is the second-cheapest US airline on the same measure, and it plays a different game: nonstop flights from smaller airports to vacation spots such as Florida, Las Vegas and Phoenix, often on days other airlines do not serve. Skipping a hub connection is the real value — it can save hours on a short trip.
Fees follow the usual ultra-low-cost pattern: carry-on bags typically cost $35–$75, checked bags are extra, and airport prices are higher than online prices — buy online. The trade-off is frequency: many routes run only a few days a week, so a cancelled flight can mean waiting days for the next one.
Best for: nonstop flights to vacation destinations from smaller airports.
3. Southwest Airlines — Best All-Round Value
Southwest is not an ultra-low-cost carrier, but its total cost is often lower than theirs once bags and flexibility are counted. Base fares run higher than Frontier’s, but a carry-on bag is free and there are no change fees.
Two recent changes matter. The famous bags-fly-free policy ended in May 2025 — a first checked bag now costs around $45, a second around $55. And Southwest began assigned seating in 2026, ending 50-plus years of open seating. Its Companion Pass — a designated companion flying with you on nearly every flight — remains one of the most valuable perks in US travel for couples and families.
Best for: families, checked bags, and travelers who may need to change plans.
4. JetBlue Airways — Most Comfortable Budget Option
JetBlue’s fares run a little higher than the ultra-low-cost carriers, but the experience is closer to a full-service airline. Even on its Blue Basic entry fare you get free Wi-Fi and free snacks on every flight, plus 32–34 inches of legroom in standard economy — more than most US carriers offer.
Its network is strongest on the East Coast, especially New York and Boston, and on transcontinental and Caribbean routes. It is not the pick for a $29 hop between small cities, but for a longer domestic flight the small fare premium often pays for itself in legroom and included extras.
Best for: longer flights, extra legroom, and free Wi-Fi without a premium fare.
5. Breeze Airways — Best Newcomer for Underserved Routes
Breeze has grown by flying direct routes between smaller and mid-size cities — places that usually need a connection through a hub — and cutting that connection out of the trip.
The limits mirror Allegiant’s: fewer flights per week on most routes, so a cancellation can mean a longer wait, and the route map does not cover everywhere.
Best for: direct flights between smaller cities that usually need a connection.
6. Avelo Airlines — Simplest Fares from Small Airports
Avelo, flying since 2021, follows a similar playbook: small airports, direct routes, low fares and a simple product, mostly to leisure markets. The appeal is convenience — cheaper parking, shorter security lines and a quicker trip to the gate. The trade-off is a thin schedule — a few flights a week on many routes — so it suits flexible travelers best.
Best for: easy airport experiences and low fares on leisure routes.
7. Sun Country Airlines — Worth Checking from the Midwest
Sun Country, based in Minneapolis, flies leisure routes from the Upper Midwest to Florida, the Southwest, Mexico and the Caribbean. Its network is small, but on the routes it flies it is often the cheapest nonstop option. It charges separately for bags and seat selection, so compare the all-in price.
Best for: leisure trips out of the Midwest, especially to warm-weather destinations.
Fees to Watch Before You Book
The base fare is a starting point, not the price. Add up the same basket for each airline: fare, carry-on, checked bag and seat. Frontier and Allegiant charge the most for bags, and their airport prices are far higher than online prices — buy bags during booking. Southwest includes a carry-on for free, which changes the math wherever you would otherwise pay $59–$99 for one. Also check the change policy: a cheap fare you cannot change is only cheap if your plans hold. Fees change often, so confirm current numbers on the airline’s own site before paying.
How to Get the Lowest Fare
Timing matters more than the airline. Book a few weeks ahead for domestic trips and fly midweek — Tuesday and Wednesday departures are typically cheaper than Friday and Sunday. Our guide to the cheapest months to fly in 2026 breaks down which months offer the lowest fares across the year.
Pack light: a trip that fits in a personal item and a free carry-on costs far less than the same trip with a checked bag, especially on Frontier and Allegiant.
Compare the all-in price, not the headline, and include smaller airports near your destination. A secondary airport can be cheaper and faster than the main hub — the model Allegiant, Breeze and Avelo are built on. Set a fare alert and be ready to move: budget sales are short and the lowest fares sell out fast.
Keep your booking accounts secure, too. Budget fares are usually bought directly on airline sites and apps, where your payment details live — our guide to password managers in 2026 covers the tools that make that safer. And if a trip stretches your budget, a small cushion helps first: see how to build an emergency fund on a low income.
Frequently Asked Questions
What is the cheapest budget airline in the USA in 2026?
Frontier, by average revenue per seat mile — cheapest for light packers. Allegiant is second. But a traveler with a checked bag often pays less on Southwest or JetBlue.
Is Southwest still a budget airline?
Yes, as a low-cost carrier rather than an ultra-low-cost one. Higher base fares, but a free carry-on and no change fees often make its total cost lower, especially for families.
Which budget airline is best for families?
Southwest, for its free carry-on and no change fees. JetBlue is next if comfort and legroom matter more than the lowest fare.
Are budget airlines safe?
All US airlines operate under the same Federal Aviation Administration safety rules. A lower fare comes from unbundled services and denser seating, not lower safety standards.
Should I book directly with the airline or a booking site?
Book directly when the price is the same — changes, cancellations and bag add-ons are easier. Use comparison sites to find the fare, then buy it from the airline.
The Bottom Line
There is no single cheapest budget airline — only the cheapest for your trip. Fly light and short, and Frontier or Allegiant usually win. Check a bag or want to change plans, and Southwest is hard to beat. Want a comfortable longer flight, and JetBlue is worth the small premium. If a direct flight from a small airport saves you a connection, Breeze, Avelo or Sun Country may be the best deal of all. Compare the all-in price every time and buy your bags online.