United vs Southwest 2026

United and Southwest represent the two major models of US air travel in 2026: the global legacy carrier with Star Alliance reach, Polaris business class, and a Basic Economy fare that strips the carry-on, versus the domestic-focused carrier with bigger carry-on allowances, the Companion Pass, and a newly assigned seating system that still gives you more legroom than most competitors.

The comparison has shifted. Southwest now charges for checked bags and assigns seats, removing two of its most distinctive advantages. But the operational data still favors Southwest on reliability, and United’s domestic Basic Economy is the most restrictive of any US legacy carrier when it comes to bags. Those differences matter more than the converging fare structures.

Short version: Southwest is better for domestic-only travelers who value reliability, flexibility, and a larger carry-on. United is better for international travelers, Star Alliance loyalists, and anyone who needs premium cabin options beyond US borders.

What We Looked For

• Basic fare restrictions, because United and Southwest have the widest gap in what their cheapest ticket includes
• Carry-on and checked bag policies, with attention to the new fee landscape after Southwest’s policy change
• Reliability, measured by on-time rates and cancellations
• Route network, domestic point-to-point versus global hub-and-spoke
• Loyalty program value, including Companion Pass versus Star Alliance access
• Seat comfort, pitch and the extra-legroom upsell on each carrier

Which airline charges less for bags, United or Southwest?

Southwest includes a carry-on on every fare for free. United strips the carry-on on domestic Basic Economy, making Southwest cheaper for most bag-carrying travelers.

This is where the comparison gets sharpest, because United and Southwest handle the cheapest ticket completely differently.

United Basic Economy on domestic routes restricts you to a personal item only: 17x10x9 inches (43x25x22 cm), no full carry-on. If you show up at the gate with a roller bag on a domestic Basic Economy ticket, United charges the checked bag fee plus a gate handling surcharge. MileagePlus Premier members and United co-brand credit card primary holders are exempt.

Southwest Basic (the cheapest of its four fare bundles: Basic, Choice, Choice Preferred, Choice Extra) includes a full carry-on at 24x16x10 inches (61x41x25 cm) plus a personal item on every fare. No restrictions, no upsell required, no credit card needed.

That is a significant gap. United’s Basic Economy is the most restrictive of the Big Three legacy carriers on carry-on bags (Delta and American both include the carry-on). For a traveler who does not hold United status or a credit card, this effectively makes the cheapest United fare $45 more expensive after adding a bag.

Checked bags. United charges $45 for the first checked bag ($50 at the airport) and $55 for the second ($60 at the airport). Southwest charges $45 for the first and $55 for the second on bookings from April 9, 2026 onward. Both airlines now charge the same prepaid online rate.

Carry-on dimensions. Southwest’s 24x16x10 inches (61x41x25 cm) is noticeably larger than United’s 22x14x9 inches (56x35x23 cm). Southwest also has a lower gate-check risk thanks to its consistent all-737 fleet, while United’s regional jets (CRJ-200, ERJ-145) cannot fit standard carry-ons.

For details on your specific bag, use our carry-on size checker or see our guide to avoiding checked bag fees.

Winner: carry-on inclusion

Southwest / included on all fares vs stripped on United Basic Economy

Winner: carry-on size

Southwest / 24x16x10 vs 22x14x9

Winner: checked bag fees

Tie / $45 first bag at both airlines

Winner: gate-check avoidance

Southwest / all-737 fleet, consistent bins

Is United or Southwest more reliable?

The two are closely matched. United is marginally ahead on on-time arrivals (78.77 percent vs 77.04 percent), while Southwest cancels less often (0.85 percent vs United’s 1.36 percent).

Both airlines are above average on reliability, and they split the two main measures.

Southwest’s full-year 2025 on-time rate was 77.04 percent (Cirium) with a 0.85 percent cancellation rate (US DOT). That cancellation rate is low, though not the lowest in the US: Allegiant (0.47 percent) and Hawaiian (0.82 percent) both came in lower for the year. Southwest was nonetheless named the best US airline of 2025 in the Wall Street Journal’s annual scorecard, helped by strong completion and the fewest customer complaints among ranked carriers.

United’s full-year 2025 on-time rate was 78.77 percent, roughly one and a half points ahead of Southwest’s 77.04 percent on punctuality. United’s cancellation rate was 1.36 percent, higher than Southwest’s but close to the industry average. Both airlines are solidly reliable in 2026.

Winner: on-time arrivals

United / 78.77% vs 77.04%, marginal

Winner: cancellations

Southwest / 0.85% vs United's 1.36% (US DOT 2025)

Does United or Southwest have more legroom?

Both offer 30 to 31 inches of standard pitch, with Southwest slightly more consistent across its all-737 fleet.

Standard economy pitch. Southwest offers 31 inches (79 cm) across its all-Boeing 737 fleet, reduced from 32 inches in 2026 to accommodate Extra Legroom rows. United’s narrowbody fleet offers 30 to 31 inches (76 to 79 cm) in standard economy.

Extra legroom. United’s Economy Plus provides 34 to 38 inches (86 to 97 cm) of pitch with priority boarding. Southwest’s new Extra Legroom rows offer a few more inches than its standard seats. Both are available as paid upgrades.

Wi-Fi. United offers free Wi-Fi for MileagePlus members on domestic flights (free to enroll). Southwest charges for Wi-Fi but offers free streaming entertainment through the app.

Entertainment. United has seatback screens on newer aircraft and streaming on others. Southwest has no seatback screens but provides free live TV and on-demand content via the app.

Assigned seating. Southwest transitioned to assigned seating on January 27, 2026. Passengers now choose Standard, Preferred, or Extra Legroom seats depending on fare level. United has always used assigned seating with Economy Plus as the paid upgrade tier.

Winner: standard legroom

Tie / both 30-31 in (76-79 cm), Southwest slightly more consistent

Winner: Wi-Fi

United / free for MileagePlus members

Winner: entertainment

United / seatback screens on many aircraft

Does United or Southwest fly to more destinations?

United flies to over 300 destinations on six continents. Southwest covers 117 domestic-focused airports with no transoceanic service.

United flies to over 300 destinations across six continents with major hubs at EWR, ORD, IAH, DEN, SFO, IAD, and LAX. Star Alliance membership connects to 26 partner airlines including Lufthansa, ANA, Singapore Airlines, and Air Canada.

Southwest flies to approximately 117 airports in 11 countries, focused on the contiguous United States, Hawaii, Mexico, Central America, and the Caribbean. No widebody aircraft, no transoceanic flights, no alliance partnerships (though individual codeshares exist).

For domestic flights, both airlines cover most major and mid-size markets. Southwest’s point-to-point model often avoids connections that United’s hub-and-spoke system requires. For international travel, United is the only choice.

Winner: international

United / 300+ destinations, 6 continents, Star Alliance

Winner: domestic point-to-point

Southwest / fewer connections on popular routes

Is MileagePlus or Rapid Rewards the better loyalty program?

MileagePlus is better for international travelers with Star Alliance access. Rapid Rewards is better for families thanks to the Companion Pass.

MileagePlus earns miles based on fare price and partner spending. Miles are worth approximately 1.5 cents each on average, with strong redemption rates on Star Alliance partners. Elite tiers (Silver, Gold, Platinum, 1K) unlock free upgrades, economy Plus, and United Club access. Premier 1K members get the broadest upgrade priority and a complimentary United Club membership.

Rapid Rewards earns points based on fare price. Points average 1.4 cents each, slightly below MileagePlus. The Companion Pass (135,000 qualifying points or 100 flights in a calendar year) lets a designated companion fly free on every flight for up to two years. No blackout dates on award flights. Free flight changes and cancellations on most fares.

Winner: international redemptions

MileagePlus / Star Alliance, 26 partners

Winner: families

Rapid Rewards / Companion Pass

Winner: flexibility

Rapid Rewards / free changes, no blackout dates

Winner: upgrade path

MileagePlus / complimentary upgrades with elite status

Who Should Pick United

• You fly internationally and need a carrier with global reach and premium cabins
• Your home airport is a United hub (EWR, ORD, IAH, DEN, SFO)
• You hold MileagePlus status or a United credit card that waives the Basic Economy bag restriction
• You value Star Alliance partner redemptions
• You want United Club or Polaris lounge access
• You fly enough to earn Premier status and complimentary upgrades

Who Should Pick Southwest

• You fly mostly domestic and want a carry-on included on every fare without needing status or a credit card
• You travel as a couple or family and can earn the Companion Pass
• You want the flexibility to change or cancel flights without fees
• You carry a larger bag that fits Southwest’s 24x16x10 inches (61x41x25 cm) but not United’s 22x14x9 inches (56x35x23 cm)
• You want a low cancellation rate (0.85 percent in 2025, below United’s 1.36 percent)
• Your travel schedule changes often and you value rebooking without penalty

The Bottom Line

United’s domestic Basic Economy is the tightest in the industry. No carry-on on the cheapest fare is a meaningful restriction for travelers who do not hold status or a co-brand credit card. Southwest includes a larger carry-on on every fare, and that alone can be worth $45 per flight in avoided bag fees.

Where United wins is everywhere outside the US border. Star Alliance access, Polaris business class, and 300+ global destinations are capabilities Southwest simply does not have and is not building toward. If you fly internationally even a few times a year, MileagePlus earns and redeems in ways Rapid Rewards cannot match.

For the domestic-only traveler, Southwest’s combination of reliability, carry-on generosity, Companion Pass, and flexibility makes it the better default in 2026. For the traveler who crosses an ocean, United is the clear pick.

For more comparisons, see Southwest vs Delta and United vs American.