Spirit Airlines offers the absolute lowest base fare in the United States domestic market. You pay extra for everything from a carry-on bag to a cup of water.
Southwest Airlines is the cheapest airline for a family of four with two checked bags each. The “Bags Fly Free” policy mathematically destroys the ultra-low-cost carrier pricing model.
This guide calculates the true total cost of a flight after all the fees. Never be fooled by a cheap base fare again.
Cheapest Airlines in USA
Spirit Airlines, Frontier Airlines, and Allegiant Air are the three cheapest base fare airlines in the United States. These ultra-low-cost carriers unbundle every single amenity to lower the advertised price.
A ticket from Chicago to Orlando might show a very low base fare on the search screen. The final price with a carry-on bag and a seat assignment can triple instantly.
Budget travelers with a small backpack that fits under the seat should always choose Spirit Airlines. The personal item is free, and the base fare is the lowest available on the route.
A family of four with a stroller, a car seat, and two checked bags should avoid Spirit completely. The baggage fees on these four tickets will erase any savings from the cheap base fare.
The DOT Air Travel Consumer Report states that ancillary fees now represent nearly half of all airline revenue. The ultra-low-cost carriers are masters of extracting this extra cash.
Cheapest Airlines in the US
Southwest Airlines is the true cheapest airline when you calculate the total cost with two bags. The base fare includes a carry-on, a personal item, and two free checked suitcases.
| Airline | Base Fare | Carry-On Fee | Checked Bag Fee | Seat Selection Fee | Best For |
|---|---|---|---|---|---|
| Spirit | Lowest | High | High | High | Solo backpacker |
| Frontier | Lowest | High | High | High | Solo backpacker |
| Allegiant | Low | High | High | High | Vacation package traveler |
| Southwest | Mid-range | Free | Free (x2) | Free open seating | Family of four |
| Sun Country | Mid-range | High | Medium | Medium | Midwest leisure traveler |
Budget travelers flying solo with a single backpack should always pick Spirit or Frontier. The total cost with zero add-ons beats Southwest on a strict price comparison.
Business travelers who need a carry-on suitcase and a specific aisle seat should price-check Southwest first. The free bags and open seating often beat a Spirit flight with all the added fees.
NerdWallet Travel identifies Southwest as the best value airline for a family checking bags. The math is simple and undeniable when you run the total cost calculation for four passengers.
Key Takeaway: Spirit is cheapest for a solo backpacker. Southwest is cheapest for a family.
Spirit Airlines vs Frontier
Spirit Airlines and Frontier Airlines are nearly identical in their ultra-low-cost business model. Both charge a fee for a carry-on bag, a checked bag, and a seat assignment.
Spirit operates the Airbus A320neo family with the “Big Front Seat” in the first two rows. This is a wider recliner, not a lie-flat bed, but it is a genuine upgrade for a tall traveler.
Frontier flies a mix of the Airbus A320neo and the Airbus A321neo with newer cabin interiors. The thinner “lightweight” seat cushion on Frontier is noticeably firmer on a long flight.
Solo travelers should compare the exact route on both Spirit and Frontier before booking. The base fares fluctuate wildly, and one carrier often undercuts the other by a wide margin on the same city pair.
A family with young children should choose Frontier over Spirit for one specific reason. The Frontier “Kids Fly Free” promotional program is a genuine money-saver for a family with a toddler.
European Low Cost Airlines
Ryanair, easyJet, and Wizz Air dominate the European ultra-low-cost airline market with aggressive pricing. A flight from London Stansted to Barcelona can cost less than a train ticket to the airport.
Ryanair uses a strict Boeing 737-800 fleet with a tight 30-inch seat pitch in standard rows. The non-reclining slimline seats are genuinely uncomfortable for a passenger over six feet tall.
Budget travelers flying around Europe should compare easyJet’s total price against Ryanair’s base fare. easyJet flies to primary airports like Amsterdam Schiphol (AMS) , while Ryanair often uses distant secondary fields.
Solo female travelers should note that Ryanair’s boarding process can feel aggressive and chaotic. Pay the small priority boarding fee to avoid the stampede and secure overhead bin space for your bag.
Skytrax ranks easyJet higher than Ryanair for overall customer experience on a consistent basis. The seat comfort and cabin ambiance are measurably better on the orange-branded airline.
Cheapest Airlines in the World
AirAsia, IndiGo, and Ryanair are consistently the cheapest airlines in the world by base fare per kilometer. These carriers operate massive fleets of high-density narrow-body aircraft with minimal cabin amenities.
AirAsia flies the Airbus A320neo across Southeast Asia with deeply discounted promotional sale fares. A flight from Kuala Lumpur to Bangkok often costs less than a hotel dinner in the city center.
Budget travelers backpacking through Asia should book AirAsia’s “Lite” fare with zero add-ons. Carry only a small backpack that fits under the seat to avoid the checked bag fee.
A solo traveler in India should use IndiGo for the cheapest domestic connections between major cities. The airline operates a massive Airbus A320 fleet with predictable, reliable, and cheap point-to-point service.
IATA reports that the Asia-Pacific region has the lowest average airfare per kilometer globally. The combination of low labor costs and dense aircraft configurations creates these dirt-cheap fares.
Key Takeaway: AirAsia and IndiGo are the cheapest airlines in the world per mile flown.
Ryanair vs EasyJet Comparison
Ryanair is almost always the absolute cheapest base fare on any given European route. The airline sells a non-refundable, no-frills ticket with very strict baggage enforcement at the gate.
easyJet offers a slightly more forgiving experience with a more generous personal item allowance. The airline flies to convenient primary airports, saving you time and a long bus transfer.
Budget travelers on a strict shoestring should pick Ryanair and travel with a single small backpack. This strategy avoids the gate-check fee, which is heavily enforced at the boarding door.
Business travelers on a quick European hop should pay the easyJet “Flexi Fare” for fast track security. The time saved at the primary airport outweighs the marginal fare difference over Ryanair’s secondary field.
The Points Guy identifies easyJet as the more traveler-friendly option for a nervous flyer. The cabin crew training and the less-aggressive gate enforcement create a calmer boarding process.
Spirit Airlines Baggage Fees
Spirit Airlines charges a fee for every single bag except one small personal item that fits under the seat. The carry-on bag fee is higher at the gate than if you prepay online during booking.
A personal item on Spirit must measure no larger than 18 by 14 by 8 inches total. The gate agents actively measure bags in a metal sizer before scanning your boarding pass.
Budget travelers must measure their backpack against the Spirit personal item sizer at home. A single inch over the limit triggers a gate fee that costs more than the original flight ticket.
A family flying Spirit should pay for exactly one checked bag and pack everyone’s clothes inside it. This is significantly cheaper than paying for a carry-on bag for each individual passenger.
Verify the current Spirit Airlines baggage fee chart on the official airline website before booking. The fee structure changes without notice, and the gate fee is always the most expensive option.
Frontier Airlines Personal Item Size
Frontier Airlines allows a free personal item with a maximum size of 18 by 14 by 8 inches. This is the exact same dimension as the Spirit Airlines personal item sizer at the airport gate.
The Frontier gate agents are among the strictest in the industry with the personal item sizer. They will force a bag into the metal cage, and a protruding handle triggers the carry-on fee.
Budget travelers should buy a backpack specifically designed to fit the “Frontier personal item” dimensions online. This single purchase saves hundreds of dollars in gate fees over a year of frequent flying.
Solo travelers with a laptop should slide the computer into a thin sleeve inside the soft backpack. A rigid laptop case in the bag makes it inflexible and harder to jam into the narrow metal sizer slot.
Always verify the current Frontier personal item dimensions on the official airline site before packing. The airline adjusts the allowable dimensions, and an old bag might no longer technically fit.
Key Takeaway: The 18 x 14 x 8 inch personal item is the key to avoiding all bag fees.
Allegiant Air Seat Selection Fee
Allegiant Air charges a seat selection fee for any specific seat assignment, even a standard middle seat. If you skip the fee, a random seat is assigned at check-in, often splitting a family group.
The “Allegiant Extra” seat in the front rows offers additional legroom for an extra upcharge. This is not a premium cabin, just a standard economy seat with a few more inches of pitch.
Budget travelers flying solo should skip the seat fee and accept the random free assignment. A middle seat at the back of the plane is a small price to pay for the lowest total fare.
A family with children must pay the seat selection fee to sit together on an Allegiant flight. The airline’s algorithm frequently separates groups who skip the fee, causing stress at the gate.
Verify the current Allegiant Air seat fee structure on the official airline website before booking. The dynamic pricing model adjusts the seat fee based on the route and the remaining available seats.
Spirit Airlines Seat Pitch
Spirit Airlines offers a tight 28-inch seat pitch in standard economy on the Airbus A320neo. This is the absolute legal minimum space between seats on a US commercial airline.
The “Big Front Seat” at the front of the Spirit cabin provides a generous 36-inch seat pitch. The seat is wider, softer, and a genuine upgrade for a tall traveler on a long flight.
Budget travelers under six feet tall will survive the 28-inch pitch for a flight under two hours. A cross-country Spirit flight from Newark to Los Angeles is a genuinely painful physical experience.
Business travelers on a short hop should pay the Big Front Seat upgrade fee without hesitation. The extra legroom and the wider seat transform the ultra-low-cost experience into a comfortable domestic first-class recliner.
SeatGuru documents the Spirit A320neo layout with the exact row-by-row seat pitch measurements. Always check the specific tail number before selecting your seat on a long Spirit flight.
Frontier Airlines A320neo Seats
Frontier Airlines uses an ultra-thin “lightweight” Acro Series 6 seat on its Airbus A320neo fleet. The seat cushion is noticeably firmer and less padded than a standard economy seat.
The seat pitch is a standard 28 to 30 inches depending on the specific row and aircraft configuration. The slimline design theoretically creates more knee space, but the comfort trade-off is real.
Solo travelers with back problems should absolutely avoid a standard Frontier seat on a long flight. The lack of padding creates a painful pressure point on the tailbone after the first hour.
A tall traveler should upgrade to the “Stretch” seat at the front of the Frontier cabin for the extra legroom. The firm cushion is still present, but the additional pitch makes the flight bearable.
The official Frontier Airlines seat map tool shows the exact pitch and width for each specific row. Use this tool to pick the best possible seat on your particular aircraft for the route.
Allegiant Air Fleet Age
Allegiant Air operates an older fleet of Airbus A319 and Airbus A320 aircraft purchased secondhand. The average fleet age is significantly higher than Spirit or Frontier’s factory-new A320neo family.
The older cabin on an Allegiant aircraft often feels worn, with scratched windows and tired plastic trim. The reliability of the in-seat power outlets, if present, is questionable at best.
Budget travelers focused purely on the lowest fare should accept the older Allegiant cabin without complaint. The plane is safe, meticulously maintained by the airline’s FAA-certified mechanics, and cheap.
Business travelers who need a functional tray table and a clean workspace should avoid Allegiant Air. The worn interior and the lack of Wi-Fi make it a poor mobile office environment.
The FAA safety record for Allegiant Air is fully compliant with all federal maintenance regulations. An older plane is not a less safe plane, just a less comfortable one on the inside.
Key Takeaway: Allegiant’s older planes are safe but uncomfortable.
Cheapest Days to Book Budget Airline Flights
Tuesday and Wednesday afternoons are the cheapest days to book a Spirit or Frontier flight. The fare sales launch on Monday evening, and the discounted seats sell out by Thursday morning.
A midweek departure on a Tuesday or Wednesday is the cheapest day to physically fly. The lowest demand period is a Tuesday afternoon at 2 p.m., and the base fares reflect this.
Budget travelers with a flexible schedule should always search for a Tuesday-to-Tuesday round-trip. This seven-day window captures the lowest fare buckets in both directions of travel.
Business travelers on a corporate Monday morning flight will pay the highest possible budget fare. The demand for a Monday 8 a.m. departure is sky-high, and the budget carriers price accordingly.
Google Flights data shows that booking a flight exactly 21 to 35 days in advance captures the lowest fare. The ultra-low-cost carriers do not follow the traditional 54-day advance purchase sweet spot.
How to Avoid Budget Airline Fees
Buy only the base fare and carry a single soft-sided backpack that fits under the seat. This is the single most effective strategy to avoid every single budget airline fee trap.
Pay for your checked bag online at the time of booking, never at the airport check-in counter. The online bag fee is significantly lower than the airport counter price, and the gate fee is the highest.
Skip the advance seat selection and accept the random free seat assignment at online check-in. A middle seat at the back of the plane is the cost of a dirt-cheap ticket.
Families with children must pay the seat selection fee to guarantee a contiguous group of seats. Skipping this fee on a budget airline will almost certainly result in a split family at the gate.
Always check the fee chart on the official airline website before entering your credit card details. A fee that was optional yesterday might be mandatory for your specific travel dates in 2026.
Norse Atlantic Airways Review
Norse Atlantic Airways is a low-cost long-haul airline flying the Boeing 787-9 Dreamliner between the US and Europe. The base fare is a fraction of a legacy carrier ticket, but the fees add up quickly.
The “Light” economy fare includes only a small personal item on a transatlantic route to London. A carry-on bag, a checked bag, and a meal all cost extra, even on a 7-hour overnight flight.
Budget travelers crossing the Atlantic should price-check Norse against a legacy carrier’s basic economy fare. The Dreamliner cabin pressure and quiet engines make the bare-bones experience physically tolerable.
Solo travelers on a long-haul flight must pay for the “Classic” fare, which includes a checked bag and a meal. The “Light” fare is a false economy for a trip that requires a suitcase at the destination.
The DOT Air Travel Consumer Report lists Norse Atlantic with a mixed on-time performance record. The low base fare reflects a thin schedule with limited rebooking options during a major delay.
Level Airlines Baggage Policy
LEVEL is the low-cost long-haul arm of the International Airlines Group (IAG) , flying Airbus A330-200 aircraft. The base fare is extremely cheap, but the baggage fees are modeled on Spirit Airlines.
A personal item is free, but a full-size carry-on bag costs a significant fee on a Level transatlantic flight. The fee is strictly enforced at the gate at Barcelona (BCN) or Paris Orly (ORY) airports.
Budget travelers flying Level to Spain should prepay for exactly one checked bag at the time of booking. The airport price for a checked bag on a Level transatlantic flight is genuinely punitive.
A family traveling with multiple suitcases should compare the Level “Premium” fare against a legacy airline. The all-inclusive premium fare often costs the same as a basic economy ticket on British Airways.
Verify the current Level Airlines baggage dimensions on the official IAG website before packing. The policy for the personal item and carry-on bag differs slightly from the US ultra-low-cost carrier standard.
Frequently Asked Questions About the Cheapest Airlines
What is the absolute cheapest airline in the United States?
Spirit Airlines offers the lowest base fare in the US for a solo traveler with a small backpack.
The fare triples if you add a carry-on bag, a checked suitcase, and a seat assignment.
Southwest Airlines is cheaper for a passenger with two bags because the bags fly free.
Is Spirit or Frontier cheaper with a carry-on bag?
Spirit and Frontier charge nearly identical fees for a carry-on bag at the gate.
Frontier occasionally offers a “Discount Den” membership that reduces the carry-on bag price slightly.
You must price-check both airlines on the specific route and date to find the lowest total cost.
Which budget airline has the most comfortable seats?
Southwest Airlines has the most comfortable standard economy seat with a 32-inch pitch.
Spirit Airlines has the best premium seat with the “Big Front Seat” in the first two rows.
Frontier Airlines has the least comfortable standard seat with a thin, firm lightweight cushion.
How do I avoid Spirit Airlines’ baggage fees?
Travel with only a small backpack that fits the 18 x 14 x 8 inch personal item sizer.
Prepay for a checked bag at the time of booking if you must take a suitcase.
Never pay for a bag at the airport gate, as this is the most expensive fee option.
What is the cheapest European budget airline?
Ryanair offers the lowest base fare on any given route in Europe.
easyJet flies to more convenient primary airports for a marginally higher base fare.
Wizz Air is the cheapest option for routes to Eastern European destinations.
Is Allegiant Air cheaper than Southwest?
Allegiant Air’s base fare is often cheaper than Southwest for a solo traveler with a personal item.
Southwest is cheaper for a family because the two free checked bags are included in the base fare.
Always calculate the total trip cost with your specific bags before deciding.
A solo traveler with a single backpack that fits perfectly under the seat should always book Spirit or Frontier. You will pay the absolute lowest possible fare for a US domestic flight.
A family of four with suitcases, a stroller, and a car seat should always book Southwest Airlines. The free checked bag policy saves hundreds of dollars on a single round-trip booking.
Budget airline fees, personal item dimensions, and seat pitch configurations shift constantly in 2026. Always verify the specific bag size and fee chart directly on the official airline website before you pack.
