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Southwest is more straightforward than most airlines when it comes to carry-ons: you get one carry-on bag + one personal item, and you’re not dealing with the “basic fare means no overhead bag” problem you see with many ultra-low-cost carriers.
The main things that still trip people up are (1) bringing a roller that’s a little too large once you count wheels/handles, (2) overpacking so it won’t stow cleanly, and (3) assuming your “personal item” can be any size as long as you call it a backpack.
Below is the quick cheat sheet, then the details.
Southwest carry-on rules at a glance
If you only read one section, make it this one—these are Southwest’s published carry-on rules and the practical points most people actually need.
- Carry-on bag (overhead bin): 24″ (L) x 16″ (W) x 10″ (H)
- Wheels/handles count: Southwest applies wheels, handles, and attachments toward those dimensions
- Personal item: One smaller item that must stow under the seat (examples: purse, briefcase, laptop case, small backpack)
- Carry-on weight limit: Southwest’s policy focuses on size and stowage; it does not list a separate carry-on weight limit in the carry-on policy
- Liquids: For U.S. departures, the TSA 3-1-1 rule applies (plain-English breakdown in my TSA liquids rule guide)
For quick comparisons across airlines, keep my carry-on size by airline guide bookmarked.
Southwest carry-on bag size limit (overhead bin)
Southwest’s carry-on bag size limit is:
- 24″ (L) x 16″ (W) x 10″ (H)
Southwest also makes the most critical “fine print” explicit: wheels, handles, and attachments count toward the dimensions. In practice, that means a bag that’s advertised as “22 inches” can still be oversized if the exterior depth balloons once you include wheels, a rigid handle housing, or stuffed front pockets.
A simple way to avoid problems
Measure your bag fully packed, from the outside, including anything that sticks out. That’s the version of your bag Southwest cares about.
Use the Southwest Carry-on Bag Sizer
If you aren’t sure if your carry-on will fit, use the Southwest carry on bag sizer located at their ticketing counters and departure gates. If your bag fits in the sizer, you can bring it on board with you. If it does not, you may have to check it.
If your bag is too big, you will have to check it, so it’s better always to know your bag size and the airline size restrictions in advance.
Southwest personal item rules
Southwest allows one personal item in addition to your carry-on. The key rule is storage: it needs to fit under the seat in front of you.
Typical examples Southwest lists include items like a purse, briefcase, laptop computer case, backpack, or small camera. The best way to avoid boarding-area stress is to treat your personal item like an “under-seat only” bag—not a second carry-on in disguise.
Southwest Airlines Carry-On Weight Limit
Southwest’s carry-on policy is centered on size and whether the bag can be stowed in the overhead bin. It does not list a separate numeric carry-on weight limit in the carry-on policy.
Practical guidance: pack your carry-on so you can safely lift it into the overhead bin without help. If you’re traveling with dense/heavy items, you may be better off moving weight into a checked bag.
Recommended Southwest Carry-On Bag
If I’m bringing an overhead-bin carry-on, the bag I’ve used for years (and still swear by) is the Travelpro Maxlite 5 Expandable Spinner. It’s lightweight, rolls smoothly, and it packs efficiently without feeling bulky.
Here are the manufacturer dimensions:
- Overall dimensions (includes wheels and carry handles): 23″ H x 14.5″ W x 9″ D
- Case dimensions (the main body): 21″ H x 14″ W x 9″ D
Does it fit Southwest’s carry-on size rules?
Southwest’s carry-on limit is 24″ (L) x 16″ (W) x 10″ (H), and the Maxlite 5’s overall dimensions (23 x 14.5 x 9) fit within that envelope with some breathing room. The one thing I still do on Southwest (and really any airline) is keep it unexpanded unless I’m confident it stays within the published maximums.
This carry-on bag has been sizer bin tested to accommodate overhead bin space on most major US airlines.
Case Dimensions:
- H: 21 in. W: 14 in. D: 9 in.
Note: If fully expanded it may not meet overhead bin size limits, so be careful to not overpack.
Southwest Liquids Policy for Carry-ons
For U.S. departures, liquids are a TSA checkpoint rule (not a Southwest-only rule). The standard TSA rule most travelers need is the 3-1-1 rule.
TSA 3-1-1 rule (the quick version)
- Containers must be 3.4 oz (100 mL) or less
- All containers must fit in one quart-size clear bag
- One liquids bag per traveler
If you want the plain-English version with examples and the “is this a liquid?” edge cases, use my TSA liquids rule guide.
Exceptions to this rule are certain medications and baby food/child nourishment.
Southwest Airlines Carry-On Pet Policy
Southwest Airlines allows small vaccinated domestic cats and dogs to travel with you in the cabin under the seat in front of you. All pets must be carried in an appropriate carrier as noted below. The pet carrier counts as either a carry-on item or a personal item.
Soft-sided and hard-sided carriers specifically designed as pet carriers are acceptable with maximum dimensions of 18.5” long x 8.5” high x 13.5” wide.
Emotional Support and Service animals have some separate guidelines. Here’s a link to Southwest Airlines’ emotional support animal rules.
TSA-Approved Pet Carrier for Southwest Airlines
If you plan on bringing your pet with you, make sure you follow TSA’s pet policy and have an approved Pet Carrier that conforms to Southwest Airlines’ pet policy.
Features mesh panels so your pet can breathe easily, a non-slip shoulder strap, locking zippers, and a rear storage pocket for treats and other goodies.
Approved for use on most major airlines and the small and medium sizes are included in Sherpa's exclusive Guaranteed on Board program.
Summary: Southwest Airlines Carry-On Policy
In conclusion, Southwest Airlines’ carry-on and checked baggage policy is the best in the industry. Their generous size limits and lack of fees make Southwest a great choice for travelers who want to have the flexibility to either carry on or check a bag without having to worry about added fees.
Here is a link to Southwest’s Carry-On page to make sure you have the most up-to-date information.
More related articles…
- 5 Tips to Travel with Just One Bag
- How to Use Packing Cubes to Travel with Just A Carry-On
- The Best Carry-On Bags for Regional and Small Jets
- Southwest Delay and Cancellation Policy
- The Southwest Low Fare Calendar Hack
Tim White is the founder of milepro.com, a luxury travel resource featured in CNBC, Travel & Leisure, and other major media outlets. With over 2 million miles flown and 30+ years of business travel experience, he holds Hyatt Globalist, Marriott Lifetime Titanium, and Hilton Diamond status — and has spent years decoding the world of luxury hotel programs, preferred partner benefits, and miles & points optimization so you don’t have to.
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What are the carry on rules for medication (pills) and vitamin supplements? Put in separate quart bag as well!
Hi Martha – It is probably a good idea to put them in a separate quart bag, but if they are not liquid, you should be fine as they are. The rule applies to liquids, not pills
I want to bring my daughter two 4in. China containers. I don’t want them to be in my luggage for fear they will break. How do I wrap them and where do I pack them?
ok When will I receive my answer?
As long as there are no liquids in them and they meet the dimensions in the carry-on rules described, you can wrap them and bring them with you as a carry-on.