Cheapest Airlines in the US Ranked

The Quick Ranking

Here's the bottom line: the cheapest airline depends on how you fly. If you travel with just a personal item and don't care about seat selection, ultra-low-cost carriers win every time. If you need a checked bag and want to pick your seat, the math changes fast.

Here's our ranking from cheapest to most expensive, based on realistic total costs for a typical domestic traveler.

Tier 1: Ultra-Low-Cost Carriers (ULCCs)

1. Frontier Airlines

Frontier consistently offers the lowest base fares in the U.S., with one-way tickets starting as low as $19 on select routes. They run frequent sales and serve a wide domestic network.

The real cost: A typical round-trip with Frontier's "Works" bundle (seat selection, carry-on, checked bag, priority boarding, no change fees) adds about $69. So a $98 base fare round-trip becomes roughly $167 all-in. Without the bundle, a carry-on alone costs $7-15 per segment and a checked bag runs $30-60 per segment.

Best for: Travelers who can fly with just a personal item (a backpack that fits under the seat). If that's you, Frontier is hard to beat on price.

2. Spirit Airlines

Spirit has long been the poster child for ultra-cheap base fares. Their model is simple: strip everything out of the ticket price and charge for it separately.

The real cost: Base fares average around $87 round-trip on competitive routes. Their "Works" bundle adds about $84, bringing the total to roughly $171. Carry-on bags cost $28-45 round-trip, and checked bags run $37-65 round-trip. Overweight bags get hit with a $125 fee, and oversized bags cost $150.

Best for: Short domestic trips where you can pack light. Spirit's "Big Front Seat" (their version of extra legroom) is actually decent value if you grab it during a sale.

3. Allegiant Air

Allegiant connects smaller cities to leisure destinations (think: Belleville, IL to Orlando) with rock-bottom fares. They fly less frequently than Frontier or Spirit, often just a few times per week on each route.

The real cost: Base fares average around $77 round-trip. Their seat, carry-on, and checked bag bundle adds about $88, bringing the total to roughly $165. Allegiant's revenue per seat mile of about $0.13 makes them one of the most efficient budget operators.

Best for: Travelers in smaller cities with limited airline options. If Allegiant serves your local airport, their fares to vacation destinations are often unbeatable.

Tier 2: Low-Cost Carriers (LCCs)

4. Southwest Airlines

Southwest isn't technically a budget airline anymore, but they deserve a spot here because of one killer feature: two free checked bags. No other major U.S. airline offers this.

The real cost: Base fares are higher than ULCCs, typically $100-200 round-trip for domestic routes. But with two free checked bags (saving $70-120 versus other airlines), no change fees, and no cancellation fees, the total cost is often comparable to or less than a ULCC with bags.

Best for: Families, anyone checking bags, and travelers who value flexibility. Their no-change-fee policy means you can rebook if fares drop.

5. JetBlue

JetBlue positions itself as a value carrier with a better experience. Their "Blue Basic" fares compete with budget airlines on price, while standard "Blue" fares include a carry-on and personal item.

The real cost: Blue Basic fares start competitive but don't include a carry-on. Standard Blue fares are typically $20-50 more than ULCCs but include more. First checked bag is $35 each way. The experience (more legroom, free WiFi, seatback entertainment) is noticeably better than ultra-budget options.

Best for: Travelers who want a good experience at a reasonable price, especially on East Coast routes and flights to the Caribbean.

Tier 3: Newer Budget Options

6. Avelo Airlines

Avelo launched to fill gaps in underserved markets, flying from smaller airports like Hollywood Burbank (BUR) and New Haven (HVN). Fares are low, and the route network keeps expanding.

The real cost: Base fares are competitive with Frontier and Spirit. Baggage fees apply but tend to be slightly lower. The limited route network means Avelo only works if they serve your airport.

Best for: Travelers near Avelo's base airports who want to avoid crowded major airports.

7. Breeze Airways

Breeze, founded by JetBlue's creator David Neeleman, focuses on underserved routes between mid-size cities. They fly brand-new Airbus A220s, which are genuinely nice planes.

The real cost: Fares are reasonable, and the experience is better than most budget carriers. Their "Nice" fare includes a carry-on, while "Nicer" adds a checked bag and better seats. Limited route flexibility since they serve fewer markets.

Best for: Travelers on routes that Breeze serves exclusively or with limited competition. The A220 aircraft is a comfortable ride.

Tier 4: Major Airlines (Budget Fares)

8-10. American, Delta, United (Basic Economy)

The Big Three all offer "basic economy" fares that strip down to compete with budget carriers. These fares typically include a personal item only (no overhead bin on United and American), no seat selection, no changes, and no upgrades.

The real cost: Basic economy fares are usually $30-80 more than ULCC base fares on the same route. First checked bag is $35 each way on American and United, $35 on Delta for most routes. But you get a more reliable operation, better on-time performance, and actual customer service.

Best for: Travelers who want the reliability and network of a major airline at the lowest possible price. These fares also earn frequent flyer miles (though at reduced rates).

The True Cost Comparison

Here's what a typical domestic round-trip actually costs when you add one checked bag and seat selection:

• Frontier - $167 (base + Works bundle)
• Allegiant - $165 (base + bundle)
• Spirit - $171 (base + Works bundle)
• Southwest - $150-200 (base fare, bags free)
• JetBlue Blue - $180-250 (base + checked bag)
• Major airline basic economy + bag - $200-300

Notice how close the prices cluster when you add bags and extras. The gap between the "cheapest" and "most expensive" airlines shrinks dramatically once you factor in real costs.

How to Actually Get the Lowest Fare

• Pack light - A personal item only (backpack under the seat) on a ULCC is the cheapest way to fly, period
• Book early - Budget carriers raise prices aggressively as departure approaches
• Check Southwest separately - Southwest fares don't appear on Google Flights or most search engines
• Compare total costs - Always add bags and seat selection to the base fare before comparing airlines
• Consider the value of your time - A $40 savings isn't worth it if the ULCC route adds a 3-hour connection
• Sign up for fare alerts - Budget carriers run flash sales frequently, and catching one can cut your fare in half

The Bottom Line

If you're truly optimizing for the lowest possible cost and can fly with just a backpack, Frontier, Spirit, and Allegiant will save you the most money. If you're checking bags, Southwest's two-free-bags policy often makes them the best total value. And if you value reliability and comfort, JetBlue and the major airlines' basic economy fares are worth the modest premium.

The "cheapest" airline is the one that costs least for how you actually travel.