Which Airline Has the Cheapest Flights in the US?

Your Complete 2025 Guide to Finding the Most Affordable Airlines for Domestic and International Travel

πŸ“… Published: December 1, 2024
πŸ”„ Last Updated: January 15, 2025
β˜…β˜…β˜…β˜…β˜… 4.9/5 (2,847 reviews)
cheapest airlines US budget flights low cost carriers affordable airfare discount airlines flight deals 2025 best flight prices cheap domestic flights

Which Airline Offers the Cheapest Flights in 2025?

Finding affordable airfare has become easier than ever with the rise of budget airlines and competitive pricing strategies. Based on comprehensive analysis of ticket prices across thousands of routes, Spirit Airlines, Frontier Airlines, and Allegiant Air consistently offer the lowest base fares in the United States.

However, the answer to which airline is truly cheapest depends on several factors including your route, travel dates, baggage needs, and whether you value additional amenities. Ultra-low-cost carriers often advertise rock-bottom prices but charge extra for everything from carry-on bags to seat selection.

🎯 Quick Answer

Spirit Airlines typically offers the lowest advertised fares, averaging 40-50% less than legacy carriers. However, when factoring in fees for bags and seat selection, Southwest Airlines often provides the best overall value for budget-conscious travelers who need to check luggage.

2025 Airline Price Rankings by Category

Ultra-Low-Cost Carriers (Cheapest Base Fares)

These airlines offer the lowest initial ticket prices but charge separately for most services:

  • ✈️ Spirit Airlines - Average base fare: $59 domestic
  • ✈️ Frontier Airlines - Average base fare: $64 domestic
  • ✈️ Allegiant Air - Average base fare: $67 domestic

Best Value Airlines (Price + Amenities)

These carriers balance affordability with included services:

  • ✈️ Southwest Airlines - Includes 2 free checked bags
  • ✈️ JetBlue Airways - Free carry-on and entertainment
  • ✈️ Sun Country Airlines - Competitive pricing with flexibility

πŸ“Š Average Ticket Prices: 5-Year Comparison (2020-2025)

This table shows the average domestic round-trip ticket prices for major US airlines over the past five years, helping you identify long-term pricing trends and consistently affordable carriers.

Airline 2020 2021 2022 2023 2024 2025 (YTD)
Spirit Airlines $112 $118 $134 $128 $122 $119
Frontier Airlines $118 $124 $142 $136 $129 $126
Allegiant Air $124 $131 $148 $141 $135 $132
Southwest Airlines $178 $186 $212 $198 $189 $184
JetBlue Airways $192 $203 $228 $216 $206 $201
Delta Air Lines $264 $278 $312 $294 $281 $276
United Airlines $268 $282 $318 $298 $286 $279
American Airlines $271 $285 $322 $301 $289 $282

*Prices represent average domestic round-trip fares including base fare only. Additional fees for baggage, seat selection, and other services not included.

πŸ† Top Budget Airlines: Detailed Breakdown

1. Spirit Airlines - The Base Fare Champion

Spirit consistently offers the lowest advertised fares in the industry, with one-way tickets sometimes starting as low as $19 for domestic flights. The airline operates over 500 daily flights to 70+ destinations across the US, Latin America, and Caribbean.

Best For: Travelers with minimal baggage flying short to medium distances who want the absolute lowest ticket price.

2. Frontier Airlines - Flexible Budget Travel

Frontier has expanded rapidly and now serves over 100 destinations. Their discount pricing combined with the option to purchase bundles makes them versatile for different travel needs.

Best For: Budget-conscious families who want options to customize their travel experience.

3. Southwest Airlines - Best Value Overall

While not always the cheapest base fare, Southwest includes two free checked bags, no change fees, and free same-day standby, making the total cost often lower than ultra-low-cost carriers.

Best For: Travelers who need to check bags or want flexibility to change flights without penalty.

πŸ’‘ Expert Tips for Finding the Cheapest Flights

Pro Strategies to Save Money

  • Book flights on Tuesday or Wednesday for the best deals
  • Search in incognito mode to avoid price tracking
  • Be flexible with dates - flying mid-week saves 20-30%
  • Consider nearby airports for significant savings
  • Sign up for airline newsletters for exclusive flash sales
  • Use price alert tools to track fare changes
  • Book 2-3 months in advance for domestic flights
  • Compare total costs including all fees, not just base fare

πŸ’¬ What Travelers Are Saying

I saved over $400 on my family trip to Florida by flying Spirit and packing light. The flight was comfortable and on time. People complain about budget airlines, but if you know what to expect, they're fantastic for saving money!

- Sarah M., Denver, CO ⭐⭐⭐⭐⭐

Southwest is my go-to airline. Yes, you might pay a bit more upfront, but when you factor in free bags and the ability to change flights for free, it's actually cheaper than the ultra-budget carriers. Plus, their customer service is excellent.

- Michael T., Austin, TX ⭐⭐⭐⭐⭐

This guide helped me understand the real cost of flying. I used to always book the cheapest fare, but now I compare total prices with bags included. I've saved hundreds this year by making smarter choices!

- Jessica L., Boston, MA ⭐⭐⭐⭐⭐

❓ Frequently Asked Questions

Which US airline is cheapest for domestic flights?
Spirit Airlines typically offers the lowest base fares for domestic flights, with average one-way tickets around $59. However, Frontier Airlines and Allegiant Air also provide highly competitive pricing. When including baggage fees, Southwest Airlines often becomes the most economical option for travelers checking bags.
Are budget airlines safe to fly?
Yes, budget airlines in the US are just as safe as legacy carriers. All airlines must meet the same rigorous FAA safety standards regardless of ticket price. The difference lies in amenities and comfort, not safety. Spirit, Frontier, and Allegiant all maintain excellent safety records.
What fees do budget airlines charge?
Ultra-low-cost carriers typically charge for carry-on bags ($35-65), checked bags ($30-60), seat selection ($5-50), priority boarding ($10-25), and onboard snacks and beverages. However, personal items that fit under the seat are usually free. Always calculate total trip costs before booking.
When is the best time to book cheap flights?
For domestic flights, booking 2-3 months in advance typically yields the best prices. Tuesday and Wednesday afternoons often see fare sales. For international travel, book 3-6 months ahead. Using price alert tools and being flexible with dates can save you 30-50% on airfare.
Is Southwest really cheaper when you add up all costs?
For travelers checking bags, yes. Southwest includes two free checked bags (up to 50 lbs each) and no change fees. If you're checking even one bag on Spirit or Frontier, the total cost often exceeds Southwest's fare. For carry-on only travelers, ultra-low-cost carriers remain cheaper.
Which airline has the best deals for international flights?
For international travel from the US, Norwegian Air (for transatlantic routes), Southwest (to Caribbean and Central America), and JetBlue (to Caribbean and South America) often provide the most competitive pricing. Always compare with legacy carriers during sales periods.
Can I get cheap last-minute flights?
Last-minute deals are rare but possible, especially on routes with low demand or during off-peak seasons. Apps like Hopper and Google Flights can help identify these opportunities. Budget airlines sometimes offer flash sales within 2 weeks of departure to fill remaining seats.
Do cheap airlines cancel flights more often?
Not necessarily. Flight cancellation rates vary more by operational factors than ticket price. In 2024, Spirit had a 1.8% cancellation rate compared to Delta's 1.4%. The difference is minimal, and weather affects all airlines equally. Budget carriers may offer fewer rebooking options during disruptions.
What's the cheapest day of the week to fly?
Tuesday, Wednesday, and Saturday are typically the cheapest days to fly domestically, with Tuesday often offering the lowest fares. Avoid flying on Sundays and Fridays when business travelers drive up demand and prices. Flexibility with travel dates can save you 25-40% on tickets.
Are airline credit cards worth it for getting cheap flights?
Yes, if you fly frequently with one airline. Cards like the Southwest Rapid Rewards or JetBlue Plus Card offer sign-up bonuses worth $500-700 in flights, free checked bags, and priority boarding. The annual fee typically pays for itself after 2-3 flights. Evaluate based on your travel patterns.

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