Carry-On Luggage Size Limits by Airline: What Actually Fits
Carry-on gear worth packing
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Sized at or just under 22 x 14 x 9 inches, this clears the strictest major-carrier limit. A hardside shell holds its shape under overhead-bin pressure better than soft-side when bins fill up fast.
See options on AmazonIf you're sizing down to clear the 22 x 14 x 9 limit, packing cubes compress clothing enough to make up most of the difference versus a looser-fitting bag.
See options on AmazonSouthwest's 24 x 16 x 10 allowance is noticeably bigger than the other majors. An expandable soft-side bag can flex between a compact size for strict airlines and the fuller Southwest allowance.
See options on AmazonCarry-on size limits by airline (inches, including wheels and handles)
| Airline | Carry-on limit | Notes |
|---|---|---|
| American Airlines | 22 x 14 x 9 | Standard major-carrier limit |
| Delta Air Lines | 22 x 14 x 9 | Also stated as 45 linear inches |
| United Airlines | 22 x 14 x 9 | Basic Economy may restrict carry-on on some fares/routes, check before booking |
| Southwest Airlines | 24 x 16 x 10 | More generous than the other majors; two free checked bags also included |
| Frontier Airlines | ~18 x 14 x 8 free (personal item) | Larger carry-on in the overhead bin costs $60 to 100 depending on when you pay |
| Spirit Airlines | ~18 x 14 x 8 free (personal item) | Larger carry-on in the overhead bin costs $65 to 100 depending on when you pay |
The math on carry-on luggage is simple once you see it laid out: three of the four largest US airlines cap you at the same size, one is more generous, and two budget carriers charge extra for anything beyond a small bag that fits under the seat.
The 22 x 14 x 9 standard
American, Delta and United all publish the same carry-on limit: 22 x 14 x 9 inches, measured including wheels and handles, not just the bag's shell. Delta also expresses this as 45 linear inches (the sum of all three dimensions), which works out to the same thing. If you fly any mix of these three, a bag sized to this limit, or slightly under it to allow for wheel housings that stick out, clears all of them.
Southwest gives you more room
Southwest's carry-on allowance is noticeably larger at 24 x 16 x 10 inches. Combined with two free checked bags, Southwest is the one major US carrier where sizing a bag to the strictest standard actually leaves usable room on the table. If Southwest is most of your flying, it's worth considering a slightly larger bag, as long as you're aware it won't clear American, Delta or United's bins.
Frontier and Spirit work differently
Frontier and Spirit don't give you a free overhead-bin bag at all by default. What's included free is a smaller personal item, sized to roughly 18 x 14 x 8 inches, that fits under the seat in front of you. Anything larger that needs the overhead bin is a paid add-on, and the fee depends heavily on when you pay: buying it in advance online runs cheaper (often in the $60 range) than waiting until the gate, where it can run as high as $100.
For these two carriers, the practical move is either sizing your bag to the free personal-item dimensions, or budgeting for the carry-on fee and paying it online in advance rather than at the gate.
Basic Economy and fare-specific restrictions
On American and Delta, Basic Economy fares generally keep the same carry-on allowance as standard fares. United has had route- and fare-specific restrictions on some Basic Economy tickets in the past. Policies on this shift, so if you're booking a restrictive fare class, it's worth a quick check of your specific itinerary before you pack around an assumption.
The practical takeaway
If your flying is a mix of American, Delta, United and Southwest, size your bag to 22 x 14 x 9 inches and you're covered everywhere except you'll have a little room to spare on Southwest. If Frontier or Spirit are regularly in the mix, treat them as a separate case: either pack to their smaller personal-item size, or plan on paying the carry-on fee online in advance rather than at the gate.
Questions people ask
What's the one carry-on size that clears every major US airline?
22 x 14 x 9 inches, including wheels and handles, clears American, Delta and United, and it's well within Southwest's more generous allowance too. It won't get you a free overhead-bin bag on Frontier or Spirit, but nothing short of their small personal-item size will.
Do Frontier and Spirit really not include a free carry-on?
They include a free personal item sized to roughly 18 x 14 x 8 inches, which fits under the seat. Anything bigger that needs the overhead bin is a paid add-on, commonly $60 to 100 depending on whether you pay in advance online or wait until the gate.
Does Basic Economy change carry-on rules on American, Delta or United?
On most Basic Economy fares the carry-on allowance stays the same as the standard fare on American and Delta. United has had route- and fare-specific restrictions in the past, so it's worth double-checking your specific fare before you fly, rather than assuming the standard limit applies.
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Sources
How we write: we research manufacturer documentation, extension-service and agency guidance, and owner discussions, then summarize what matters before you buy. We do not claim hands-on testing unless a pick is marked "We own and use this one." Spot an error? Tell us.