Which has the bigger carry-on allowance, Southwest or United?

Southwest: 24 × 16 × 10 in (61 × 41 × 25 cm). United: 22 × 14 × 9 in (56 × 36 × 23 cm). Southwest allows the larger bag.

Which is more reliable, Southwest or United?

In 2025 Southwest arrived on time 77.8% of the time (0.8% cancelled) and United 77.7% (0.8% cancelled), according to U.S. DOT data.

Which has more legroom, Southwest or United?

Standard economy legroom is about 31 in on Southwest and about 30 in on United. Both sell extra-legroom seats.

Which has better Wi-Fi, Southwest or United?

Southwest: Free for Rapid Rewards members since October 2025. United: Free for MileagePlus members on Starlink-equipped planes (fleetwide by end of 2027); otherwise paid.

Which cancels fewer flights, Southwest or United?

In 2025 Southwest cancelled 0.8% of its flights and United 0.8%, close to a tie (U.S. DOT data).

Are Southwest and United partners?

They aren't in the same alliance (Southwest: none; United: Star Alliance), so miles and status generally don't transfer between them.

WN vs UA · 2026 comparison

Southwest vs United

Q: Do Southwest and United include a carry-on on basic economy?

Southwest: Even the Basic fare includes a carry-on and a personal item. Checked bags cost extra on Basic, Choice and Choice Preferred fares. United: Basic Economy includes only a personal item on most U.S. and short-haul flights. A full-size carry-on is allowed on transatlantic, transpacific and South America routes, and for MileagePlus Premier members and eligible United cardmembers.

Southwest wins on a bigger carry-on, a carry-on on its cheapest fare, a bigger personal item, more legroom and better Wi-Fi access; United doesn't clearly win any category. Here's how they compare on bags, fees, comfort, reliability and loyalty.

Verified Oct 17, 2026By Steven MoHow we check Report a correction

Southwest

Wins 5 categories

A bigger carry-on
A carry-on on its cheapest fare
A bigger personal item
More legroom
Better Wi-Fi access

United

No clear category wins

Quick verdict

Southwest wins on a bigger carry-on, a carry-on on its cheapest fare, a bigger personal item, more legroom and better Wi-Fi access; United doesn't clearly win any category. Check the cheapest fare's bag rules before you compare prices.

Carry-on size: Southwest: 24 × 16 × 10 in · United: 22 × 14 × 9 in
Carry-on on the cheapest fare: Southwest: Included on every fare · United: Not on some basic fares
First checked bag (regular economy): Southwest: $45 · United: $45
Standard economy legroom: Southwest: About 31 in · United: About 30 in
Wi-Fi: Southwest: Free for members · United: Free on some planes
On-time arrivals (2025): Southwest: 77.8% · United: 77.7%

Side by side

	Southwest	United
Bags
Carry-on size	24 × 16 × 10 in	22 × 14 × 9 in
Carry-on on the cheapest fare	Included on every fare	Not on some basic fares
Carry-on weight limit	None published	None published
Personal item	16.25 × 13.5 × 8 in	17 × 10 × 9 in
First checked bag (regular economy)	$45	$45
Comfort
Standard economy legroom	About 31 in	About 30 in
Wi-Fi	Free for members	Free on some planes
Reliability
On-time arrivals (2025)	77.8%	77.7%
Flights cancelled (2025)	0.8%	0.8%
Network
Alliance	None	Star Alliance
Loyalty program	Rapid Rewards	MileagePlus
Main hubs	DEN, LAS, MDW, BWI, DAL	ORD, DEN, IAH, EWR, SFO

Highlighted values are better for travelers. Fees are for U.S. domestic economy flights; on-time data is 2025 U.S. DOT figures for each airline's own flights.

Bags and fees

Southwest allows a carry-on up to 24 × 16 × 10 in (61 × 41 × 25 cm), and United up to 22 × 14 × 9 in (56 × 36 × 23 cm), so Southwest's is roomier.

Southwest includes it on every fare, while United's Basic Economy can be personal-item only.

Neither publishes a carry-on weight limit.

Personal items: 16.25 × 13.5 × 8 in (41 × 34 × 20 cm) on Southwest, and 17 × 10 × 9 in (43 × 25 × 23 cm) on United.

A first checked bag on Southwest costs $45 on flights within the U.S. mainland, and a first checked bag on United costs $45 on U.S., Canada, Mexico, Central America and Caribbean flights.

Basic economy

Southwest (Basic): Even the Basic fare includes a carry-on and a personal item. Checked bags cost extra on Basic, Choice and Choice Preferred fares.

United (Basic Economy): Basic Economy includes only a personal item on most U.S. and short-haul flights. A full-size carry-on is allowed on transatlantic, transpacific and South America routes, and for MileagePlus Premier members and eligible United cardmembers.

Seats and Wi-Fi

Southwest gives about 31 in of legroom in standard economy and United about 30 in, an edge for Southwest. Southwest: 31 in standard since assigned seating began; Extra Legroom rows 34–36 in. United: About 30 in in Economy; 34 in or more in Economy Plus.

Wi-Fi on Southwest: Free for Rapid Rewards members since October 2025. On United: Free for MileagePlus members on Starlink-equipped planes (fleetwide by end of 2027); otherwise paid.

On-time performance

In 2025, Southwest landed 77.8% of its flights on time and cancelled 0.8%; United landed 77.7% on time and cancelled 0.8%. That's close to a tie. The figures come from the U.S. DOT and count each airline's own flights, not regional partners.

Loyalty and where they fly

Southwest is not in an alliance and United is in Star Alliance.

Loyalty programs: Rapid Rewards (Southwest) and MileagePlus (United).

Southwest's main hubs are Denver (DEN), Las Vegas (LAS), Chicago (MDW), Baltimore (BWI), Dallas (DAL). United's are Chicago (ORD), Denver (DEN), Houston (IAH), Newark (EWR), San Francisco (SFO). The best choice often comes down to which airline flies nonstop from your airport.

Which should you book?

Choose Southwest if you want…

a bigger carry-on
a carry-on on its cheapest fare
a bigger personal item
more legroom
better Wi-Fi access
nonstops from DEN, LAS, MDW

Choose United if you want…

to earn and use Star Alliance miles and status
nonstops from ORD, DEN, IAH

On a route both fly, the cheaper ticket isn't always the cheaper trip: add the bags you'll actually bring, and check the fare rules before you book.