Southwest Airlines Carry-On Size: Rules and Tips
Updated September 2026.
This article contains affiliate links. We may earn a commission at no additional cost to you if you make a purchase through these links. See our affiliate disclosure for details.
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 even without assigned seats or first class.
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 personal item dimensions are slightly larger than some competitors, so you get a little extra under-seat room.
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 at boarding group C (the last group), overhead space is often gone, meaning your carry-on may need to be gate-checked regardless of size. Getting an earlier boarding position (A or B group) avoids this.
How Southwest Compares to Other Airlines
Southwest’s free bags policy is increasingly rare among US carriers. Compared with other US airlines:
Delta, United, American: One carry-on + one personal item on most fares. Basic economy on some routes restricts you to personal item only. No free checked bags except for elite status.
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. Carry-on costs $35-$65+ depending on when you pay. This is where Southwest’s policy creates the biggest savings. A round trip with a carry-on on Frontier can cost $70-$130 in bag fees alone.
JetBlue: One carry-on + one personal item on most fares. Similar to mainline carriers. Blue Basic restricts to personal item only.
For travelers who fly with carry-on luggage regularly, Southwest’s free bag policy saves $100-$200 per year compared to Frontier, even if the ticket price is slightly higher. The bag fee savings often make Southwest the cheaper total option.
Tips for Flying Southwest with Carry-On
Get Early Bird Check-In or check in exactly 24 hours before departure to secure an A or B boarding group. Boarding position determines your overhead bin access. A1-A30 always gets bin space. B31+ starts getting tight. C group often means gate-checking.
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.
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. It clears Southwest’s personal item box on every dimension, so it stays with you under the seat even if the carry-on gets gate-checked in the C group. 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, which is half an inch wider than the figure Southwest lists. In practice it slides under a Southwest seat and no gate agent is measuring a personal item, but the half inch is worth knowing 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.
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 the jet bridge or baggage claim upon arrival. 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