Cheapest Airlines in the US - Budget Carrier Rankings 2025

Amy Lancelotte

By:  Amy Lancelotte

10 minutes read

Last Updated:  12 November 2025

Flights can be one of the more expensive components of any trip, so it’s useful to know the cheapest airlines in the US if you need to save money. It’s not surprising that most of the budget carriers we reviewed rank higher on our list.

We reviewed the average passenger revenue per seat mile, which takes into account more than the base fare price. It includes things like seat selection and onboard services to get the full picture.

• In 2024, US airlines had over $247 billion in operating revenue.
• The average net 2024 profit margin was 2.7%.
• We reviewed 10 US airlines to determine the average passenger revenue per seat mile in 2023 and 2024.
• The average revenue for airlines per seat mile in both years ranged from $0.095 to $0.18.

Let’s get to our AirAdvisor list of the cheapest US-based airlines to fly in 2025 and explore the outliers. To form our top 10 list, we averaged out the revenue per available seat mile for each carrier in 2023 and 2024. Some airlines billed as low-cost don’t rank as well as you might think.

Top 3 Cheapest Airlines in the US

#1 Frontier Airlines

What is the cheapest airline in the US? Based on our research, Frontier Airlines has the lowest total passenger revenue per seat mile of the 10 airlines we reviewed. Their number of $0.095 per seat mile seems low; in fact, they all do. But think about how many actual miles your plane is flying. Costs can definitely start to mount up.

Frontier Airlines is often referred to as an ultra-low-cost carrier, and this certainly rings true based on our research. US airlines don’t get any cheaper than this as a whole. For destinations in the US, Central America, and Mexico, check with them first – they are more than $0.01 per mile cheaper than the next airline.

#2 Spirit Airlines

The second-cheapest airline on our list is Spirit Airlines, another ultra-low-cost carrier that flies throughout the US, the Caribbean, and Latin America. As for their average revenue per available seat mile, that’s $0.11, which, as mentioned, is more than one cent above our number 1 cheapest airline.

Spirit Airlines is known for promoting the “Bare Fare,” which is simply a charge for your seat and one personal item. There are no frills with Spirit, but that means it’s much easier to keep your overall flight cost low.

#3 Hawaiian Airlines

In the third-place spot, we start to see some anomalies. Hawaiian Airlines is not considered a low-cost carrier in the technical sense, although the AirAdvisor Cheapest Airline Score might beg to differ. As the highest-ranking non-budget airline, Hawaiian Airlines’ seat mile revenue average for both years was $0.12, another full cent above Spirit Airlines.

Hawaiian Airlines is an ideal choice for travel to and from Hawaii from Asia, the South Pacific, and, of course, North America. If you’re planning a trip that involves the Aloha State in any way, Hawaiian Airlines is often a cheap option.

Plus, based on our overall research, Hawaiian Airlines is by far the best combination of reliability and price of any airline we reviewed. You can also dive into the Most Reliable Airlines in the US if reliability is a crucial factor for you.

If you’ve experienced an unreliable airline and your flight has been delayed by 3 hours or more, compensation may be an optionUse our free flight checker to see if you qualifyCheck Your Flight

How the Others Stack Up - Spots 4 Through 10

#4 JetBlue

The fact that JetBlue is a low-cost airline (not ultra) means its position after the top 3 makes sense. It’s just a little surprising that Hawaiian Airlines ranks better than this so-called budget-friendly carrier.

JetBlue’s revenue per seat mile averaged out to $0.131, very close to our next carrier. JetBlue is also among the most comfortable US-based airlines, so this combination of flight comfort and price is ideal!

#5 Allegiant Air

In the number 5 spot, we have Allegiant Air, which, unsurprisingly, is another ultra-low-cost airline. Allegiant’s revenue per seat mile is $0.1313, narrowly missing fourth place.

Allegiant Air is still a good option for budget-conscious travelers and remains one of the cheapest domestic airlines, but this airline only flies within the US. Zero international destinations are available currently, and the best they can do is get you near (not to) Canada.

#6 Alaska Airlines

After Hawaiian Airlines, Alaska Airlines is the next cheapest non-budget airline in the US. The carrier offers domestic flights and flights from US cities to Canada, Mexico, Costa Rica, Guatemala, the Bahamas, and Belize. Their average revenue per seat mile is $0.146, which puts them above the overall average of the 10 airlines of $0.14.

Although Alaska Airlines is above the mid-range of our cheapest airlines, don’t immediately rule them out. The company offers flash sales throughout the year, so it’s worth checking their prices, especially if you want to avoid a no-frills budget airline.

#7 Southwest Airlines

Although Southwest Airlines is technically the world’s largest low-cost carrier, the airline’s total revenue per seat mile is starting to get up there at $0.157. So, travelers who think that Southwest offers the lowest prices are in for a surprise. This brings forth the question of whether Southwest should even be considered a budget carrier.

That being said, at least part of the reason for Southwest’s higher prices is that they don’t just offer customers the basic seat and one personal item. In 2023 and 2024, Southwest offered free checked bags, which definitely added value. Unfortunately, this service is ending in 2025.

#8 United Airlines

At $0.167 per seat mile, United Airlines is certainly not the cheapest airline out there, but it is the top major overseas US airline to appear in the rankings. Although fares may be higher than average with United, the airline offers extensive routes throughout the world, more specifically to the 6 inhabited continents.

If you’re planning to fly long distances, United is a solid option that will balance price and comfort.

#9 American Airlines

The numbers keep climbing, and American Airlines, at number 8, is definitely one of the pricier carriers you can choose. Their 2023 and 2024 revenue per seat mile averages out to $0.172 and is not far off the last entry on our list.

American Airlines is another of the US’s major carriers with an enviable selection of routes. If you need to get somewhere on a certain day at a certain time, check out the fares with American, as the flights are frequent, and over 350 destinations in 60 countries are available.

#10 Delta Airlines

Delta Air Lines is the most expensive of our 10 airlines with a revenue per seat mile of $0.178. As an airline, Delta has many strengths, but price isn’t one of them. Although the carrier ranks the worst in this category, overall, Delta was the best US airline in our study.

Delta offers flights all over the world, so there is a place for them on the itinerary of even the most budget-conscious traveler. Their website has a section for current flight deals, and you can subscribe to their newsletter to be informed whenever new sales start.

Delta is among the most reliable and comfortable airlines we reviewed, which might help explain their higher prices. If you are one of the unlucky ones and experience an interruption on a Delta flight (or a flight from any other airline), we can help. It’s often possible to claim compensation for delayed flights and instances of denied boarding.

According to our extensive research, budget airlines aren’t always the most reliableIf you’ve flown with any of the airlines on our list and encountered a delay, you might be eligible for compensation.
Check now!

Cheapest International Airline in the US

Determining the cheapest international airline is easy if you take “international” in the truest sense of the word. Of the airlines that fly to any country other than the US, the cheapest airline would be the same as our overall winner, Frontier Airlines. They fly to the Caribbean, Mexico, and Central America. But, in truth, their destinations are quite limited.

For anyone searching for the cheapest international airline that flies to destinations like Asia, Europe, South America, and Africa, the frontrunner is United Airlines. Some other airlines fly to one or two of these destinations, but United Airlines is the cheapest carrier that has multiple flights throughout North America and 5 other continents.

AirAdvisor US Airline Affordability Rating - Top Carriers Ranked

Comparison: 2023 vs 2024

Since we have data for both 2023 and 2024, we thought it would be useful to see which airlines’ revenue per seat mile increased year on year and which ones actually went down.

Our comparison reveals a clear trend in the average seat revenue decreasing. The only airline to show an increase was Spirit, and the highest decrease goes to Southwest. As a result, Southwest jumped from 9th place in 2024 to 7th in 2025, and we can’t wait to see what 2026 brings!

Our Data

To determine the cheapest airlines in the US, our methodology was fairly simple. We looked at each airline’s publicly available balance sheet for 2023 and 2024. We used the total passenger revenue per seat mile that they published to rank them, averaging out both years. The lower the dollar amount, the higher the ranking.

Conclusion

Many things go into determining the ideal airline for your next business trip or vacation. If you’d like an overall view of these same 10 airlines and how they rate in 9 different categories, including cost, check out our post on the Top 10 Airlines in the US.

Our AirAdvisor Cheapest Airlines Score should be used anytime you are planning to book a flight. When cost is important to you, check with the highest-ranked airline that flies to your destination first and then expand out from there. Many factors can influence the cost of an individual flight, like when you book and when you fly, and airlines also offer sales and discounts when flights aren’t as full as they want. Keep this in mind, and use our rankings as a guide to start your search.

FAQ

Author:

Amy Lancelotte

Job/Position: Senior Writer & Content Creator

Amy Lancelotte is a Senior Content Writer and editorial contributor at AirAdvisor with more than seven years of experience producing research-driven articles for global audiences. Her work focuses on travel, aviation, and air passenger rights, with an emphasis on factual accuracy, verified data, and clear, reader-first explanations.

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