Airline Carry-On Rules

This is the highest-stakes section on the site, because a wrong number here costs you money at a gate. Every limit in it was read from the carrier’s own published baggage policy on 3 September 2026, every row cites the page it came from, and every row carries the date it was checked. Where a carrier publishes no figure — and several publish no personal-item dimensions at all — the cell reads Not published rather than a guess.

There is no single American carry-on standard. Six of the eleven US carriers we track publish 22 × 14 × 9 in. Southwest publishes 24 × 16 × 10 in. United’s personal-item box is 17 × 10 × 9 in while American’s is 18 × 14 × 8 in — nearly twice the volume. A bag bought to fill one allowance will not fit the other.

What this section answers

• What size is a carry-on, per airline — the full table, and the bags whose published dimensions clear it.
• Whether a backpack counts as a personal item — it does, up to a box that varies by more than you would think.
• How much a carry-on may weigh — most US carriers publish no limit at all, and the ones that do are tighter than most hardshell cases leave room for.
• How to measure a bag the way an airline does — wheels and handles included, which is the step everybody skips.
• How many liters a carry-on holds — the conversion, worked, and why the answer is a range and not a number.

Why this got stricter

Two things happened at once. Carriers unbundled the carry-on from the cheapest fare, which turned bag size into a revenue line rather than an operational detail. And the US carrier field consolidated — Spirit ceased operations entirely in May 2026 — which removed one of the more permissive published boxes from the market. The longer explanation is here, including what it means for what you should buy.

One consequence worth stating: most carry-on size tables you will find online still list Spirit. Ours does not, and says why. Keeping this data genuinely current is the only real asset a new site in this category can build.

How this data is kept

Every figure in this section was read from the carrier’s own published baggage policy, not from another comparison site. Each row links to the page it came from and carries the date of the check, and the rows are re-verified on a monthly cycle. The date you see is the real date of that verification rather than the date the site last deployed — this site redeploys daily for the price refresh, and a build-stamped freshness claim would be a lie told automatically.

Where a carrier publishes nothing, the cell reads Not published. Three US carriers publish no personal-item dimensions at all, and most publish no carry-on weight limit. Those are real answers and we would rather print them than fill a column with a plausible guess. If you find a figure that has moved, tell us — corrections to this section go to the front of the queue.

The two numbers worth memorizing

22 × 14 × 9 in for the overhead bag, and 18 × 14 × 8 in for the under-seat bag. The first is published by seven of the carriers here and a bag inside it fits every one of them. The second is the largest personal-item box any major US carrier publishes, and on the four airlines that charge for the overhead bag it is the entire free allowance — around 30 L of usable space for nothing.

The one number that will catch you out is United’s personal-item box at 17 × 10 × 9 in, which is 24% less volume than American’s. If United is in your rotation, size for United and everything else fits automatically.