Carry-on size rules by airline (2026 guide)

Airline carry-on rules look simple until they bite you at the gate. A bag that cleared the sizer on your last trip can get pulled on a full flight, and a basic economy fare that seemed like a deal can turn into a checked-bag fee you didn't budget for.

Airline carry-on size limits at a glance

The four largest US carriers share a common standard, with one outlier and one policy trap that catches travelers off guard.

Delta, United, and American all use the same 22 x 14 x 9 inch maximum. That figure is the FAA-referenced benchmark most major US carriers have adopted, and bags like the Travelpro Maxlite 5 are built to clear it. TSA does not set or enforce bag size limits at all; enforcement is entirely the airline's responsibility at the gate. Southwest's larger allowance means a bag that technically exceeds the 22-inch standard can fly free on Southwest but get snagged on the others.

For personal items, the limits tighten considerably. United allows up to 17 x 10 x 9 inches. Delta and American both allow up to 18 x 14 x 8 inches. Southwest's personal item limit is 16.25 x 13.5 x 8 inches. In every case the personal item must fit under the seat in front of you.

If you are shopping for a bag that works across all four airlines, see our picks for the best carry-on luggage sized to the 22 x 14 x 9 inch standard.

Basic economy carry-on rules, broken out by airline

This is where the real variation lives, and where a $30 fare difference can cost you $75 at the gate.

United Basic Economy is the strictest. On domestic United Basic Economy fares, you are limited to one personal item (max 17 x 10 x 9 inches) that must fit under the seat. If you bring a full-size carry-on to the gate, United charges the standard checked bag fee plus a $25 gate handling fee, which totals roughly $75. The fee applies even if bins have space. Exceptions apply on select international routes and for elite-status passengers, but the domestic rule is firm.

Delta Basic Economy (sold as "Main Basic") technically allows a carry-on on all fare classes. The practical catch is boarding position: Main Basic passengers board last. On busy routes, overhead bins are frequently full by then, and the bag gets gate-checked for free. Free is better than $75, but you still lose it until baggage claim. If staying out of the checked-bag queue matters, either pay for an earlier boarding group or pack everything into a personal item.

American Airlines includes a full-size carry-on for all fare classes including Basic Economy, making it noticeably more generous than United on this point. You board in the last group on a basic fare, so the same bin-space risk exists, but there is no fee if your bag gets gate-checked.

Southwest has no basic economy tier. All fares include a carry-on plus a personal item, and two checked bags are also free. The carry-on limit is 24 x 16 x 10 inches.

United Basic Economy charges you roughly $75 at the gate for a carry-on you thought was free. Know this before you book.

How to measure your bag correctly

Manufacturer-listed dimensions are often measured empty, handle retracted, expansion zipper open, and sometimes without wheels. None of those reflect what a gate agent sees. Measure your bag the way it will actually be carried.

Avoiding a gate check

A gate check is rarely a disaster, but it costs time at baggage claim and, on United Basic Economy, real money. These habits reduce the risk.

Board as early as you can. Credit card priority boarding (available on most co-branded airline cards at no annual boarding-group cost) puts you on the plane before the overhead bins fill. This matters most on Delta and American Basic Economy, where you would otherwise board last.

On Southwest, the boarding position you earn from check-in time (or purchase with EarlyBird) determines overhead bin access. Check in at exactly the 24-hour mark if you did not pay for EarlyBird.

If you are connecting through a hub airport on a full flight, the inbound connecting flight often offloads carry-ons involuntarily at the gate before the final leg. Flag your bag as a "gate-return" item so it comes back to you at the jetbridge rather than baggage claim.

Pack to your bag's closed nominal dimensions, not the expanded ones. If you consistently need the expansion zipper to close your bag, the bag is the wrong size for the amount you pack; a fixed-shell hardside like the Away Carry-On 22 removes the temptation entirely.

FAQ

For gear that clears these limits across every major carrier, browse our travel gear hub. Curious how we vet these specs and where the numbers come from? See how we research and rate.