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Will this bag fit? 6 US airlines, 2 carry-on limits and 3 under-seat limits
There is no standard carry-on size. Southwest allows 24 × 16 × 10 inches and Delta stops at 22 × 14 × 9 — so a bag bought for one is two inches over on the other. Enter yours below and every answer is quoted from the airline’s own page, with a link to it.
Inside the carry-on limit American Airlines publishes, on this fare.
“Cannot exceed 22 x 14 x 9 inches (59 x 39 x 23 cm) including handles and wheels”
Smaller aircraft change this answer
American Eagle regional aircraft: “If your carry-on is larger than the personal item dimensions, you must valet your bag before boarding.” (We’ll tag and check your bag at the gate for you at no charge.)
Every published limit, side by side
Largest side first, because a sizer does not care which side an airline calls the length: United writes its limit as 9 × 14 × 22 and American writes the same box as 22 × 14 × 9.
| Airline | Carry-on (in) | Under-seat (in) | Weight | Watch for |
|---|---|---|---|---|
| Frontier Airlines | 24 × 16 × 10 | 18 × 14 × 8 | 35 lb | Base fare includes no overhead bag. |
| Southwest Airlines | 24 × 16 × 10 | Not published | None published | Nothing fare-specific published. |
| American Airlines | 22 × 14 × 9 | 18 × 14 × 8 | None published | Its own cm figure runs 1.4in looser than its inches.American Eagle regional aircraft: personal item only. |
| JetBlue | 22 × 14 × 9 | 17 × 13 × 8 | None published | Nothing fare-specific published. |
| Delta Air Lines | 22 × 14 × 9and 45 linear in | Not published | None published | Delta Connection flights, including flights with 50 seats or less: personal item only. |
| United Airlines | 22 × 14 × 9 | 17 × 10 × 9 | None published | Basic Economy includes no overhead bag.CommutAir, operating as United Express: personal item only. |
Where these figures come from
- Airline policy pageAmerican Airlines carry-on policy· read 30 Jul 2026
- Airline policy pageUnited Airlines carry-on policy· read 30 Jul 2026
- Airline policy pageDelta Air Lines carry-on policy· read 30 Jul 2026
- Airline policy pageSouthwest Airlines carry-on policy· read 30 Jul 2026
- Airline policy pageJetBlue carry-on policy· read 30 Jul 2026
- Airline policy pageFrontier Airlines carry-on policy· read 30 Jul 2026
Sourced information, not legal advice.
Spirit Airlines is not listed. Not an operating carrier. Its own support site states it is winding down all operations and tells guests not to go to the airport, so publishing a bag-fit answer for it would send a passenger to a flight that does not exist. Its notice, read 2026-07-30.
If the bag is going in the hold, the connection changes too
A bag taken at the gate comes off at the carousel, and on a tight connection that turns a walk into a wait. If you are connecting rather than flying point to point, the transfer math matters as much as the sizer.
- Layover guides — published terminal transfer times at LAX, DFW, IAH and MIA.
- LAX terminal transfers — the one hub here that publishes a figure per terminal pair rather than a single airport-wide number, so a gate-checked bag has a knowable cost in minutes.
- Delayed or damaged bag — what the airline owes once a checked bag goes missing.
- Who controls your ticket — booked through an agency, the bag fee is often theirs to fix, not the airline’s.
- Claim letter templates — if a fee was charged against a rule the airline’s own page does not support, the quote above is the evidence and these are the letters.
FAQ
Carry-on sizes, answered
Every answer below is drawn from the same dataset the calculator uses.
Is there a standard carry-on size for US airlines?
No. Across the 6 carriers on this page there are 2 published carry-on limits. Southwest and Frontier allow 24 × 16 × 10 inches; American, United, Delta and JetBlue stop at 22 × 14 × 9. A bag sized to the larger figure is two inches over on the other 4. Under-seat limits diverge further: of the 3 that are published, no two are the same, and Delta and Southwest publish no measurement for a personal item at all.
Why does my bag fit the airline's centimetres but fail its inches?
Because some carriers do not convert their own figures accurately. American publishes 22 × 14 × 9 inches and then gives 59 × 39 × 23 cm, but 22 inches is 55.9 cm, not 59 — its centimetre figure is roughly 1.4 inches more generous than its inch figure. The sizer at the gate is a physical box built to the inches, so this tool compares in inches and converts whatever you type.
Does a Basic Economy ticket include a carry-on bag?
Not on United. It states that on most trips you may bring only one personal item in Basic Economy, and that you cannot bring a carry-on bag unless you are flying to South America, across the Atlantic or across the Pacific. A Frontier base fare is the same shape: the personal item is included and the carry-on is a paid add-on. On those fares a correctly sized bag is still refused, because the ticket rather than the bag is the problem.
What does it cost if my bag is taken at the gate?
United is the only carrier here that publishes the figure: for tickets bought on or after 3 April 2026, bag fees start at $45 prepaid, $50 in the lobby and $75 at the gate. American states it valets bags on regional aircraft at no charge, and Frontier states a bag may be gate-checked at no additional cost when the bin is full. The others describe gate-checking without publishing a price, so no figure is shown for them.
Do wheels and handles count toward the limit?
Yes, on every carrier here. All six say so explicitly — Southwest counts “wheels, handles, and any attachments”, and Frontier adds straps. Measure the bag as it will be presented, not the shell.
Why is Spirit not listed?
Spirit Airlines is excluded because it is no longer an operating carrier. Its own support site states it is winding down all operations and tells guests not to go to the airport, so a bag-fit answer for it would be advice about a flight that does not exist.
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