Southwest and Frontier compete on hundreds of domestic routes but sell fundamentally different products. Southwest bundles a carry-on, free changes, and loyalty point earning into every fare. Frontier sells a bare seat and charges for everything else. On paper, Frontier’s base fare is almost always lower. In practice, the total trip cost depends entirely on whether you need a bag.
This distinction used to be sharper when Southwest offered two free checked bags. That policy ended in May 2025. Southwest now charges $45 for the first checked bag and $55 for the second. But Southwest still includes a carry-on on every fare, and Frontier still charges $59 to put a bag in the overhead bin. For the traveler who flies with a roller bag, Southwest’s bundled approach saves $59 per flight in carry-on fees alone before you compare fare prices.
For the minimalist traveler who flies with a backpack that fits under the seat, Frontier is genuinely cheaper. If that is you, Frontier’s base fare plus zero add-ons is the lowest total cost in US aviation. For everyone else, add the carry-on fee to Frontier’s fare, compare it to Southwest’s all-in price, and you will usually find Southwest is the same price or less.
What We Looked For
- Total trip cost, not base fare, because ULCC pricing is meaningless without add-on math
- Carry-on policies, the single biggest cost difference between these two airlines
- Reliability, where the gap is large and clear
- Seat comfort, including Frontier’s 28-inch standard pitch versus Southwest’s 31 inches
- Loyalty programs, Companion Pass versus GoWild Pass for frequent travelers
- Route overlap, where both airlines compete on the same domestic corridors
Which airline charges less for bags, Southwest or Frontier?
Southwest includes a free carry-on on every fare. Frontier charges $59 for one, making Southwest cheaper for any traveler who brings a bag.
This is the section that determines which airline is cheaper for your specific trip.
Carry-on. Southwest includes a carry-on (24x16x10 inches) on every fare. No fee, no bundle required. Frontier charges $59 for a carry-on (also 24x16x10 inches) when added at booking. The price rises at check-in, at the counter, and at the gate, where it can exceed $100. Frontier also enforces a 35-pound carry-on weight limit with scales at the gate. Southwest has no carry-on weight limit.
Personal item. Southwest’s personal item limit is 18.5x8.5x13.5 inches. Frontier’s is 14x18x8 inches. Both fit a standard backpack. Frontier enforces its sizer strictly, so if your bag does not fit the box, you pay the carry-on fee at the gate.
Checked bags. Southwest charges $45 for the first checked bag and $55 for the second (tickets booked from April 9, 2026). Frontier uses fully dynamic pricing, with checked bags typically costing $47 to $63 at booking and more at check-in or the airport. Southwest’s flat rate is comparable or cheaper depending on when you buy.
The math on a round trip with one carry-on:
A Frontier base fare of $49 plus a $59 carry-on each way equals $167 round trip ($49 + $59 = $108 each way, $216 round trip). Wait, let me recalculate: $49 base each way = $98 base round trip, plus $59 carry-on each way = $118 in bag fees, total $216. A Southwest fare of $89 each way with carry-on included equals $178. Southwest is $38 cheaper despite a higher base fare.
The breakeven point shifts when you fly personal-item-only. A Frontier $49 round trip versus a Southwest $89 round trip saves $80 for the traveler who packs light. That is real money.
For details on your specific bag, use our carry-on size checker or see our guide to avoiding checked bag fees.
- Winner for carry-on inclusion: Southwest (free on all fares vs $59 on Frontier)
- Winner for carry-on weight policy: Southwest (no weight limit vs 35 lb enforced)
- Winner for checked bag fees: Southwest ($45 flat vs Frontier’s dynamic $47-63+)
- Winner for personal-item-only travel: Frontier (lower base fares when no extras are needed)
Is Southwest or Frontier more reliable?
Southwest is significantly more reliable, with a 79.92 percent on-time rate and a 0.82 percent cancellation rate versus Frontier’s 74 percent and 1.26 percent.
Southwest is dramatically more reliable.
Southwest’s 2025 on-time arrival rate was 79.92 percent with a 0.82 percent cancellation rate, the lowest cancellation rate in the US airline industry. Southwest finished first in the Wall Street Journal’s 2025 overall airline rankings.
Frontier’s full-year 2025 on-time rate was approximately 74 percent, though monthly performance varied widely (89.3 percent in October 2025, much lower in winter). Frontier’s cancellation rate was approximately 1.26 percent. Frontier tied with American Airlines for last in the WSJ’s 2025 rankings.
The gap is nearly six points on on-time arrivals and Frontier’s cancellation rate is 50 percent higher. Over 20 flights a year, that is the difference between one late arrival and three or four.
Frontier’s lower flight frequency on many routes (often just one or two daily departures versus Southwest’s three to five) makes a cancellation more painful. If your Frontier flight cancels, rebooking options on the same day are limited. Southwest’s higher frequency provides more same-day alternatives.
- Winner for on-time arrivals: Southwest (79.92% vs ~74%)
- Winner for cancellations: Southwest (0.82% vs 1.26%)
- Winner for rebooking options after disruption: Southwest (more daily frequencies on shared routes)
Does Southwest or Frontier have more legroom?
Southwest offers 31 inches of seat pitch versus Frontier’s 28 to 29 inches, a two-to-three-inch gap that is noticeable on any flight over two hours.
Neither airline is luxurious, but Southwest gives you more room.
Standard economy pitch. Southwest offers 31 inches of seat pitch across its all-737 fleet. Frontier offers 28 to 29 inches on its all-Airbus A320 family fleet. That two-to-three-inch gap is significant. At 28 inches, most adults over 5’8” will have their knees touching the seat in front of them.
Extra legroom. Southwest’s Extra Legroom rows (introduced with assigned seating in January 2026) offer 34 to 36 inches. Frontier’s Stretch seats offer 33 to 38 inches. Both are paid upgrades. Frontier’s top-end Stretch rows are roomier, but they cost extra on top of an already fee-laden base fare.
Seat width. Southwest’s 737 seats are approximately 17 to 17.5 inches wide. Frontier’s A320 seats are approximately 17.8 inches. Marginal advantage to Frontier on width, but the pitch difference dominates the comfort equation.
Wi-Fi. Southwest charges for Wi-Fi but offers free streaming entertainment through the app. Frontier offers Wi-Fi for purchase and free on-demand entertainment through the Frontier app. Neither provides free fleet-wide Wi-Fi.
Entertainment. Neither airline has seatback screens. Both rely on streaming through their respective apps. Southwest offers free live TV through the app. Frontier’s streaming library is more limited.
- Winner for standard legroom: Southwest (31” vs 28-29”)
- Winner for extra legroom top-end: Frontier (Stretch up to 38”)
- Winner for seat width: Frontier (17.8” vs 17-17.5”, marginal)
- Winner for free entertainment: Southwest (free live TV via app)
Does Southwest or Frontier fly to more destinations?
Both serve roughly the same number of airports (117 vs 115), but Southwest offers more daily frequencies and flies to Hawaii, which Frontier does not.
Both airlines cover similar domestic territory but with different operating models.
Southwest serves approximately 117 airports in 11 countries with a point-to-point domestic model. Primary markets include MDW, DAL, LAS, DEN, BWI, HOU, MCO, and PHX. Southwest flies to Hawaii, Mexico, Central America, and the Caribbean. No widebody aircraft, no alliance partnerships.
Frontier serves approximately 115 destinations with a hub-light model centered on Denver (DEN), with significant operations from Orlando (MCO), Las Vegas (LAS), Atlanta (ATL), Philadelphia (PHL), and Miami (MIA). Frontier’s network focuses on major domestic markets. International service is limited to Mexico and the Caribbean.
On routes where both compete (Denver to Las Vegas, Orlando to Chicago, Phoenix to Dallas), fares are competitive and the comparison comes down to bags and reliability. Southwest typically runs more daily frequencies on these shared routes.
- Winner for domestic breadth: Tie (both ~115-117 airports)
- Winner for flight frequency: Southwest (more daily departures on popular routes)
- Winner for Hawaii: Southwest (Frontier does not serve Hawaii)
- Winner for international leisure: Southwest (more Mexico, Central America, Caribbean routes)
Is the Companion Pass or GoWild Pass a better deal?
The Companion Pass is better for planned travel with a partner. GoWild is better for solo, spontaneous travelers who can book one day in advance.
Both airlines have a signature loyalty feature, but they work completely differently.
Southwest Rapid Rewards earns points based on fare price with no blackout dates. Points average 1.4 cents each. Free flight changes and cancellations on most fares. The Companion Pass (135,000 qualifying points or 100 flights in a calendar year) lets a designated companion fly free on every flight for the rest of that year and the entire following year. For couples and families who fly Southwest regularly, the Companion Pass can save thousands of dollars annually.
Frontier FRONTIER Miles earns miles on flights and purchases. The loyalty program is less developed than Rapid Rewards but has one unique feature: the GoWild All-You-Can-Fly Pass at $349 to $599 per year. GoWild lets you book unlimited flights for one cent plus taxes and fees (typically $14 to $40 per flight). The catch: domestic flights can only be booked one day in advance. You must be extremely flexible, live near a Frontier hub, and travel with only a personal item to make it work.
The Companion Pass is the better value for planned travel. You know your flights in advance, you book a companion free, and you save money predictably. GoWild is the better value for spontaneous, flexible travelers who can fly on 24 hours’ notice and do not need a bag. These are very different travel styles.
- Winner for planned travel savings: Rapid Rewards (Companion Pass)
- Winner for spontaneous/flexible travel: FRONTIER Miles (GoWild Pass at $349-599/year)
- Winner for flexibility: Rapid Rewards (free changes, no blackout dates)
- Winner for point value: Rapid Rewards (1.4 cents vs lower FRONTIER Miles value)
Is a Southwest fare or a Frontier bundle cheaper overall?
Southwest’s all-in fare is usually cheaper than Frontier’s base fare plus the PERKS bundle, because Frontier’s $138 round-trip add-ons close the fare gap quickly.
Since Frontier strips everything from the base fare, comparing Frontier’s bundles to Southwest’s all-in fares is the most honest way to evaluate total cost.
Frontier The PERKS ($69 per direction) includes a carry-on, checked bag, and seat selection. On a round trip, that is $138 on top of the base fare. Frontier The WORKS ($99 per direction) adds priority boarding, refundability, and free changes, totaling $198 on top of base fare.
Southwest Wanna Get Away includes a carry-on and personal item in the fare. Checked bag is $45. Seat selection is included (assigned at booking or check-in depending on fare level). Changes are free (fare difference or credit applies).
On many routes, a Southwest Wanna Get Away fare is cheaper than a Frontier base fare plus The PERKS bundle, because the $138 in Frontier add-ons closes the fare gap quickly. The only scenario where Frontier is consistently cheaper with a bundle is on routes where Frontier’s base fare is $50 or more below Southwest’s. That happens on some routes but not most.
- Winner for bundled value: Southwest (most inclusions at the base fare level)
- Winner for base fare transparency: Frontier (you see exactly what you pay for)
Who Should Pick Southwest
- You travel with a carry-on and want it included in the fare
- You value on-time reliability (79.92 percent vs ~74 percent)
- You fly with a partner or family and can earn the Companion Pass
- You want free changes and cancellations without penalty
- You prefer 31 inches of legroom over 28 inches in standard economy
- You need higher daily flight frequency for rebooking flexibility
- You fly to Hawaii (Frontier does not serve Hawaii)
- You carry a bag over 35 pounds (no weight limit on Southwest)
Who Should Pick Frontier
- You always fly personal-item-only and never check or carry on a bag
- You want the absolute lowest base fare and are willing to skip every extra
- You have a flexible schedule and the GoWild Pass makes sense for your lifestyle
- You want Stretch seating at 33-38 inches of extra legroom
- You fly routes where Frontier’s base fare is significantly lower than Southwest’s
- You do not mind the risk of a higher cancellation rate and lower on-time performance
The Bottom Line
Southwest and Frontier represent the two poles of domestic US air travel pricing. Southwest bundles everything into the fare and charges a higher base price. Frontier strips everything out and charges a lower base price. The question is not which airline is cheaper in the abstract. The question is which is cheaper for you, on your route, with your bags.
For the personal-item-only traveler who packs light and values the lowest possible total cost, Frontier wins. The base fares are lower, and you pay nothing extra. For everyone else, add Frontier’s $59 carry-on fee to the base fare and compare it to Southwest’s all-in price. More often than not, Southwest is the same price or less, and you get 31 inches of legroom, higher reliability, Companion Pass eligibility, and free changes.
The reliability gap seals it for risk-averse travelers. Southwest’s cancellation rate is 35 percent lower than Frontier’s, and its on-time rate is nearly six points higher. If getting there on time is worth paying a modest premium, Southwest is the clear pick. If saving $30 to $80 per trip is worth accepting more delays and less legroom, Frontier has earned its market.