Southwest Airlines Carry-On Size: Rules and Tips
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Southwest Airlines allows one carry-on bag and one personal item per passenger, both free, on every fare. There is no basic-economy cut that strips the bag. That policy has been in place for decades, and it is a main reason people fly Southwest. What has changed is boarding: Southwest now assigns every seat, and your boarding group, 1 through 8, decides how much overhead bin space is left when you reach your row.
The carry-on size limit is generous compared with budget carriers. The numbers below are what fits, what does not, and what gate agents actually check.
Southwest Carry-On Size Limits
Carry-on bag: 24 x 16 x 10 inches (including handles and wheels). This is larger than many airlines allow. A standard 22-inch carry-on suitcase fits well within these limits. Even some "large carry-on" bags that get flagged on United or American fly fine on Southwest.
Personal item: Southwest does not publish a personal-item inch box. The bag has to go under the seat. A standard backpack, purse, laptop bag, or briefcase fits. Southwest's own examples are a purse, briefcase, laptop case, backpack, blanket or small camera, and a neck pillow doesn't count against your allowance.
Both bags fly free. There's no weight limit for carry-on bags on Southwest (unlike international carriers that enforce 15-22 pound limits). You can pack your carry-on as heavy as you can lift into the overhead bin.
Southwest allows 24 x 16 x 10 inches against the 22 x 14 x 9 legacy box most airport sizers are built to. Our luggage size visualizer draws a bag at true scale inside that standard frame next to a 5 ft 7 in person, which makes Southwest's extra inches easier to see.
What Southwest Enforces at the Gate
Southwest is among the most lenient US carriers for carry-on enforcement. Gate agents rarely pull out measuring devices. If your bag fits in the overhead bin, it's accepted. The sizer boxes exist at gates but are used mainly when flights are full and bin space is tight.
Enforcement still shows up in two cases. On very full flights (holidays, spring break routes), gate agents may check oversized bags and ask passengers to gate-check them for free. And the later you board, the less bin space is left. Basic fares board last, so on a full flight a Basic passenger's carry-on is the one most likely to be gate-checked regardless of size. A Choice Extra fare, an Extra Legroom seat or Priority Boarding puts you on the plane ahead of most of the cabin.
How Southwest Compares to Other Airlines
Southwest's free carry-on is increasingly rare among US carriers, even though Southwest now charges for checked bags on most fares. Compared with other US airlines:
Delta, United, American: One carry-on and one personal item on most fares. United Basic Economy is the exception: on most trips it allows only the personal item, unless you're flying to South America, across the Atlantic or across the Pacific. Delta and American keep the carry-on on their cheapest fares.
Those three publish a smaller overhead box than Southwest (22 x 14 x 9). The under-seat bag is a separate limit. We compared personal item vs carry-on sizes for each carrier.
Frontier: Personal item only for free. The carry-on is a paid add-on or part of a bundle, and Frontier says its price varies with your travel dates and when you buy it. This is where Southwest's policy creates the biggest savings.
JetBlue: One carry-on and one personal item on all fares, Blue Basic included, with a 22 x 14 x 9-inch overhead box like the mainline carriers.
For travelers who fly with a carry-on regularly, Southwest's free carry-on can make it the cheaper trip even when its fare is a little higher than Frontier's. Add Frontier's carry-on price for your dates before you compare.
Tips for Flying Southwest with Carry-On
Pick your fare with the overhead bin in mind. EarlyBird Check-In and the A, B and C groups are gone. Southwest now sets your boarding group from your fare, seat and status, so checking in the moment the window opens no longer moves you up.
Basic fares board last, in Group 8. Choice fares board in Groups 3 to 7, Choice Preferred in Groups 3 or 4, an Extra Legroom seat in Group 2 and Choice Extra in Group 1. Primary Rapid Rewards cardmembers board in Group 5 or earlier. On a cheaper fare, Priority Boarding can be bought 24 hours before departure, when available, and boards you ahead of Group 1. With a full-size roller bag on a packed holiday flight, that's the upgrade we'd pay for.
Use a soft-sided bag if you're worried about fit. Soft bags compress and flex into tight bin spaces. Hard cases either fit or they don't.
Pack a personal item backpack as your "insurance" bag. If your carry-on gets gate-checked, your essentials (laptop, charger, medication, headphones) stay with you under the seat. We covered the best personal item backpacks that maximize under-seat space.
Bags That Fit Southwest's Limits
Southwest's numbers are 24 x 16 x 10 for the carry-on. They do not publish personal-item inches. These three sit inside those figures and follow the advice above: soft sides for the overhead bin, a real backpack for under the seat.
Travelpro Maxlite 5 21-Inch Spinner
23 x 14.5 x 9 inches leaves margin on every side of Southwest's limit, and soft sides give you the squeeze the tips above describe when the bin is nearly full. Southwest sets no carry-on weight limit, so empty weight only matters for how easily you can lift the packed bag into the bin.
This is the insurance bag. At 6.3 inches deep it slides under the seat in front of you with room to spare, so it stays with you even if the carry-on gets gate-checked when you board late. The two inch expansion is the useful part: zip it closed to go under the seat, open it up once you land.
Built to the 18 x 14 x 8 spec that Frontier publishes. Southwest publishes no personal item inches, only that the bag goes under the seat in front of you. In practice it slides under a Southwest seat and no gate agent is measuring a personal item, but check each airline's box if you are buying one bag to use across every airline.
At a Glance: The Three Bags
FAQ
Does Southwest charge for carry-on bags?
No. One carry-on and one personal item fly free on every Southwest fare. No fare class takes that allowance away. The policy has been in place for decades. Checked bags are different: most fares now pay for them, though Choice Extra fares and A-List Preferred members still get two free, and A-List members and Rapid Rewards cardmembers get one.
What size carry-on does Southwest allow?
24 x 16 x 10 inches, including handles and wheels. This is larger than most US airlines allow. A standard 22-inch carry-on suitcase fits easily within these limits.
Does Southwest have a weight limit for carry-ons?
No. Southwest doesn't enforce a weight limit for carry-on bags. The only practical limit is what you can lift into the overhead bin yourself. International flights on partner airlines may have different rules.
What happens if my carry-on doesn't fit on Southwest?
If overhead bin space runs out (common on full flights for late boarding groups), Southwest will gate-check your bag for free. It goes in the cargo hold and you pick it up at baggage claim at your final destination. Take out power banks, spare batteries, e-cigarettes and lighters before you hand it over, as Southwest requires, and keep medication and keys with you. Your personal item stays with you under the seat.
Can I bring a backpack and a suitcase on Southwest?
Yes. The suitcase is your carry-on (overhead bin) and the backpack is your personal item (under seat). Both fly free. The usual Southwest setup is a rolling carry-on plus a backpack as a personal item.
Filed in Travel Tips