Carry-On Size Limits by Airline: The Numbers Every US Carrier Publishes

The number most US airlines publish for a carry-on is the same number: 22 × 14 × 9 inches. American, Delta, United, Alaska, JetBlue and Hawaiian all state it on their own baggage pages, and all of them specify that it includes wheels and handles. Southwest publishes a larger allowance, and the ultra-low-cost carriers publish their own figures alongside a fee.

That is the part everyone agrees on. The part that trips people up comes later, when the bag they bought — sold as “carry-on compliant” — turns out to be an inch over in one dimension.

What each airline publishes

Airline	Carry-on limit (in)	Personal item (in)	Weight limit
American Airlines	22 × 14 × 9	18 × 14 × 8	None enforced on most fares
Delta Air Lines	22 × 14 × 9	Not published as dimensions	None enforced on most fares
United Airlines	22 × 14 × 9	9 × 10 × 17	None enforced on most fares
Alaska Airlines	22 × 14 × 9	Not published as dimensions	None enforced
JetBlue	22 × 14 × 9	17 × 13 × 8	None enforced
Southwest	24 × 16 × 10	Under-seat only	None enforced
Spirit	22 × 18 × 10	Small personal item	40 lb
Frontier	24 × 16 × 10	Small personal item	35 lb

Figures are those published by each airline on its own baggage information pages. Check your fare before you rely on any of them: basic economy on American, Delta and United restricts the overhead carry-on, and on some routes a bag that meets the dimensions still gets gate-checked because the bins filled.

The table is the headline, and the fare is the rule. The same airline holds a bag to the sizer on a basic economy ticket that would pass on a standard one, and the ultra-low-cost entries come with a fee attached rather than an allowance. Neither the dimensions nor the enforcement attaches to the airline alone, which is why the baggage page for the specific fare class is the one worth bookmarking.

How gate sizers actually decide it

A sizer is a metal frame cut to the airline’s published dimensions, and the test is simpler than any policy document: the bag goes in, and either it fits or it does not. Wheels count, handles count, external pockets count, because the frame measures the bag at every point that touches it. A bag that needs a shove or sits proud of the frame is over, no matter what the tag says.

In practice the frame is a formality as often as an instrument. At a busy gate the decision is usually made at a glance, which favours bags that look close to the limit and disfavours bags that look over it even when they are not. Soft shells hold an advantage in that moment for a second reason: they compress into the frame where a hard shell keeps its shape.

The seat at the gate is also where the penalty gets decided. A bag refused at the sizer is gate-checked, which on the fee-charging carriers means paying the fee at the worst possible moment, with a queue behind you and the boarding order already moving.

The personal item column runs on the same logic with smaller numbers. An under-seat limit of 18 × 14 × 8 or 17 × 13 × 8 describes a bag that has to disappear under the seat in front of you, and the space down there is shaped by the aircraft, not the policy: a seat with an entertainment box in it accepts less than the published figure, and an exit-row seat accepts more. That is why a backpack that “counts as a personal item” in one aircraft wedges badly in another, and why the personal item is measured more often than the carry-on — it is checked on every boarding, not just the suspicious ones.

Why your bag’s spec sheet disagrees with the airline

Two reasons, both common.

The brand measures the shell; the airline measures the bag. Manufacturers frequently publish the body dimensions and list wheels, handles and external pockets separately, or omit them. Airlines measure the whole thing at its widest points. A “22-inch” bag with a 2-inch wheel housing and a flush handle is often 23 or 24 inches as the airline measures it.

Sources disagree with each other. Published dimensions for the same suitcase vary between the brand page, retailer listings and third-party reviewers — sometimes by more than an inch in a single dimension. When you see two different figures for the same bag, the larger one is usually the one that includes everything protruding, and that is the one that matters at the gate.

The practical rule: measure your own bag. Extend the handle, stand it on its wheels, and take the number at the outermost points. If that number is over the airline’s figure, the bag is over — regardless of what the product page says.

The regional jet problem

A bag that fits a mainline overhead bin can fail on a regional jet. Embraer 175 and CRJ-series aircraft have smaller bins, and roll-aboards that pass the sizer are routinely gate-checked on those aircraft anyway. Soft-shell bags have an advantage here: they compress. A hard-shell case either fits or it doesn’t.

Regional aircraft also flip the usual incentive. On a mainline flight the bin space is generous enough that an inch rarely matters; on a regional jet it never is, and valet-tagging happens at the jet bridge before anyone measures anything. Travellers who connect through regional hubs more than a few times a year end up packing for the smaller aircraft rather than the mainline one, because the smaller aircraft is the binding constraint on the itinerary.

What actually gets enforced

US carriers rarely measure bags at the gate. The airlines that do enforce dimensions and weight consistently are the European budget carriers — Ryanair and Wizz Air keep sizers at many gates and charge at the gate — and Spirit and Frontier, for whom carry-on fees are revenue. Several Asian carriers enforce weight rather than size.

None of this means the limit doesn’t apply. It means the risk is asymmetric: a bag a little over the line usually sails through on a US domestic flight, and usually doesn’t on a budget carrier in Europe.

The asymmetry is also why the anecdotes contradict each other. Two travellers can own the same over-limit bag and report opposite experiences, because the outcome depends on the route, the aircraft, the fare and the mood at the gate. The published limit is the only number that holds across all of those variables.

Enforcement style differs as much as enforcement frequency. A sizer checks shape; a hand scale checks weight; a full flight checks neither, because the binding constraint becomes bin space and every bag over a soft count goes below anyway. Reading the policy is therefore only half the preparation. The other half is knowing which constraint the flight you are on will actually apply.

The weight limits nobody reads until the counter

The dimensions column gets all the attention and the weight column does the damage where it is enforced. Spirit caps the carry-on at 40 lb and Frontier at 35 lb, and both are known to weigh bags, which turns the limit from fine print into a number at the counter.

Clothing is light; the dense cargo is not. Footwear, a toiletry kit, chargers and a laptop push a packed 22-inch case toward its weight limit faster than the volume suggests, and a bag that feels manageable by its handle can be several pounds past the line once it is full. The cheap check is a bathroom scale: weigh yourself, weigh yourself holding the packed case, and subtract.

Weight limits also bite at the jet bridge rather than the sizer, where a hand scale settles the question in seconds. A bag refused on weight cannot be fixed by rearranging anything, because the problem is mass, not shape.

Measuring before you buy

If you’re choosing a bag rather than checking one you own, the useful number isn’t the capacity in litres. It’s the external footprint with wheels and handles included, compared against 22 × 14 × 9. Capacity figures are useful for deciding between two bags that already fit; they say nothing about whether either one does.

Measure in the store where the bag stands, not from the listing. Two minutes with a tape against the manufacturer’s published footprint settles whether the listing numbers can be trusted at all, and a listing that disagrees with the bag in front of you has told you something about every other figure on that page.

Take three numbers, all with the case standing on its wheels: height to the top of the collapsed handle, width at the widest point including any side pockets, and depth at the thickest point including the wheel housings. A bag that tapers or bulges is judged at its maximum in each dimension, which is the same standard the sizer applies. Write the three down; they are the numbers every future airline comparison runs against, and they outlast the product page that may not. A bag that clears all three at its widest points clears the sizer, and a bag that misses by an inch in one of them is already known before the airport.

Three cases, three footprints

It helps to have reference points, so here are three that sit at different places on the range.

Away The Carry-On publishes 21.7 × 13.7 × 9.0 inches — inside the standard limit on paper, with a textured shell that hides scuffs better than glossier finishes. The recurring complaint in long-term owner reports is handle wobble after heavy use.

Monos Carry-On Pro publishes 22.0 × 14.0 × 9.0, which is exactly the limit rather than under it. Its Hinomoto wheels are the part reviewers single out, and the front laptop compartment means security without unpacking — though that compartment is space taken out of the main cavity.

Travelpro Maxlite 5 21” publishes 21.75 × 15.75 × 7.75 — the widest of the three and by far the lightest at roughly 5.4 lb. Fabric compresses, which matters on regional jets, but there’s no rigid protection for anything fragile.

Published dimensions for all three vary between sources by up to an inch in a single dimension. That variance is itself the argument for measuring the bag you actually receive rather than trusting any listing.