Why bags get stopped at the gate

Almost none of it is because people failed to read the rules. Here is what actually goes wrong, and what to do about each one.

Every figure below is computed from 83 airlines and 58 bags · sources read through 1 September 2026

1. The label is not the number at the gate

This is the most common reason a compliant-looking bag gets turned away, and most guides never mention it.

A suitcase has two honest sizes. There is the space you pack into, and there is the outside of the object — wheels, feet, handle housing and all. Both are real measurements of the same bag, and they can differ by several centimetres. An airline only ever uses the second one.

The better manufacturers publish both and say which is which. Travelpro states outright that the overall figure is the one to compare against an airline's limit; Rick Steves lists packing and with-wheels dimensions side by side. The number degrades as it travels: by the time the same bag reaches a marketplace listing, it often carries a different set of dimensions from every seller, with no indication of which measurement anyone took.

Even the airlines are not immune. United publishes its carry-on limit in inches and in centimetres on the same page, and the two figures disagree: a bag can pass one and fail the other. Where that happens we take the stricter number on each side.

We take dimensions from the manufacturer's own overall figure, never a reseller listing, and we name the source on every bag. Our methodology→

2. Three bags, three places

Most bad outcomes start with treating "carry-on" as one category. It is three, and the difference is about where the bag physically goes.

A personal item is much smaller than people picture, and on the cheapest ticket from some airlines it is all you get — not a smaller suitcase, no suitcase. That catches more people than any size limit does, and it is section 5.

3. How to check your own bag

Two minutes and a tape measure. Worth doing once for a bag you will fly with for years.

1. 1
   Empty it and stand it upright

   On a hard floor, against a wall. A packed bag bulges, and the bulge is what gets caught.

2. 2
   Push the handle all the way down

   An extended handle is not how it is measured. Leaving it up will frighten you for no reason.

3. 3
   Measure the widest point on each side

   Not the flat face. Wheels, feet, handle housing, and any pocket that sits proud when the bag is full.

4. 4
   Write it down to the nearest half centimetre, rounding up

   Rounding down is how you talk yourself into a fee.

5. 5
   Compare it against the airline, not the label

   And against the airline you are actually flying, on the fare you actually bought.

We do not do this ourselves — we are not a testing lab and we have not had 58 suitcases through the door. Our figures come from each manufacturer's own published overall dimensions, and every bag on this site names where its number came from.

4. Who actually checks

Knowing a limit is not the same as knowing whether anyone enforces it. A bag a centimetre over is a non-event at one airline and a fee at another.

At the strict end, catching bags has been paid work. A US Senate subcommittee found that two ultra-low-cost carriers paid $26 million to gate agents and other personnel across 2022 and 2023 for catching passengers with bags that allegedly broke the policy, with staff able to earn as much as $10 for each bag a passenger was forced to check at the gate.

Senate Permanent Subcommittee on Investigations, press release, 26 November 2024 — read in full. The $26 million is a joint figure and belongs to neither carrier alone.

So we score every airline on how likely its published limit is to be enforced — not on how tight the limit is, which is already the box we compare against. Where nobody has researched an airline yet, it starts strict, because being over-cautious costs you convenience and the other direction costs you a fee.

Most of these are still the starting prior for the airline's business model and region rather than researched enforcement. That is stated on each airline rather than smoothed over.

There is a third case worth knowing: regional jets. On a CRJ-200 or an ERJ-145 the overhead bins are smaller than the airline's own published limit, so a completely legal bag can still be taken at the aircraft door. It is handed back at the door on arrival and it costs nothing — but if you were relying on having it with you, plan differently.

5. The ticket trap

The same bag, the same airline, the same aircraft — and a different answer, because of which fare you bought.

Only differences we have read from the airline's own page appear here. A fare with no cabin row in our data is a page nobody has read yet, not a fare that forbids a bag, and we will not print one as the other.

6. Weight against pieces

Two different systems for checked bags, and mixing them up on a connecting trip is expensive.

The trap is the connection. Put both systems on one trip and the rules change between legs. The strictest one is what you have to pack for.

Weight catches people out in the cabin too. Cabin weight caps in our data run from 5 kg at Air China, UTair, XiamenAir upwards, and 18 airlines cap a cabin bag at 7 kg or less. That matters more than it sounds: 23 of the 57 bags we hold a weight for use more than half of a 7 kg allowance while completely empty. The heaviest is 4.94 kg before you put a single thing in it.

7. If you're already over

Usually fixable, and rarely by buying anything.