Airline baggage sizes

What it's for

Every airline has different carry-on limits: going over means paying a fee at the airport. Here you check the sizes before you go.

Note

Rules change often and depend on the fare you bought: always check the airline's official website before your flight.

The three measurements that decide, and the fourth that surprises

The stated limits are length, width and depth, but the number that counts is the third, the thickness: that is what decides whether the case fits the sizer, and nearly every bag that gets stopped is over on that dimension and not on the two large sides. The sizer at the gate is a rigid cage, and it does not grant a single centimetre.

The fourth measurement is the one nobody checks: wheels and handles are included in the stated dimensions. A case sold as «cabin size» can turn out to be oversized precisely because of the two centimetres of the wheels, and that is the commonest cause of fees paid at the gate.

Why the same case passes and then does not

Because the limit depends on the fare and not on the airline: the same airline with the basic ticket allows only a small bag under the seat, and with the higher fare a trolley in the locker too. Someone who has flown ten times without trouble and pays on the eleventh has not changed case, they have changed fare.

The second reason is a full flight: when the lockers are full, excess bags are put in the hold, often free but not always. And it is why fragile items, medicines and documents belong on your person or in the small bag, not in the trolley.

Weight, which is the second trap

Many airlines state a weight limit as well as a size one, and some hardly ever check it until there is a reason to. But when they do, the scales are at the check-in desk and the fee is more expensive than the one paid online: adding a bag at the airport costs double or triple.

A calculation hardly anyone makes: an empty hard-shell case already weighs between two and four kilos, that is up to a fifth of the allowance. On a ten-kilo limit the difference between a light case and a sturdy one is almost two kilos of extra belongings, which is more than rolling your clothes will ever gain you.

Liquids, and the exceptions hardly anyone knows

The hundred-millilitre rule concerns the capacity of the container, not how much is in it: a 200 ml bottle half empty is confiscated, a full 100 ml one passes. They all have to fit in a transparent resealable bag of about a litre, one per passenger.

The exceptions exist and must be declared at security: medicines with a prescription, baby food and special diets. Some airports have installed new-generation scanners that let you leave liquids and laptop in the bag, but the rule is not uniform even within one country: it is always wise to prepare for the stricter case.

Nearby tools

For what may be carried there is What to take on a plane, and to pack Packing checklist. For the journey Flight duration, Jet lag and Plug sockets around the world.