What Is IATA’s Recommended Cabin Bag Size?

A suggested optimum of 55 x 35 x 20 cm, not a mandatory limit. Your airline sets the real rule.

Published October 31, 2026 · 3 min read · Topic: Travel & Airline Rules · Travel rules

Typical situation

You are shopping for a carry-on bag and have seen “IATA approved” on a product page. You want to know what that means, and whether the bag will be accepted by your airline.

Main answer · berabags Editorial Team · Rules view

IATA’s Cabin OK guideline recommends a cabin bag of up to 55 x 35 x 20 cm (about 21.5 x 13.5 x 7.5 in). It is a suggested size, not a mandatory limit, and each airline sets its own rules. IATA says the aim is to make better use of the space in the overhead bins.

What Cabin OK is and is not

It is an optimum size recommendation from the airline industry’s trade body.
Airlines that take part may give priority to bags that meet it when bin space is limited.
It does not replace an airline’s own size and weight limits, which can be larger or smaller.
It does not guarantee that your bag will stay in the cabin. Airlines can ask for a bag to be gate-checked for operational or safety reasons.

What this means when you buy a bag

A bag that fits the Cabin OK size is likely to fit in a bin on many aircraft, but it is no guarantee of acceptance. If you fly several airlines, compare their published limits with the bag’s outside measurements. Some low-cost airlines allow only a smaller bag under the seat on the cheapest fares.

How to check

Find the airline’s cabin baggage page and note the maximum size and weight.
Measure your bag in all three directions, including handles and wheels.
Weigh it when it is packed.
Check again just before you fly.

Where this answer stops

This explains IATA’s guideline as published by IATA. It does not state any airline’s current rules. Limits change, so use the airline’s own page.

Sources and further reading

Three more perspectives

berabags Editorial Team · Purchasing view

Treat “IATA approved” on a product page with care. IATA’s guideline is a recommended size, not a certificate for individual bags. Ask what the seller’s claim rests on, and compare the stated dimensions with your airline’s page.

berabags Editorial Team · Selection view

Measure the outside of the bag, including wheels, handles and pockets, not only the main body. A bag that is just inside the limits on paper can be too big when it is full, so leave a little room and avoid overstuffing.

berabags Editorial Team · Use view

Check the airline’s own page for the size and weight limit on the day you book, and again before you fly, since limits can differ by fare and by route. Keep the page or a screenshot, in case the staff at the gate ask.

Independent and unofficial. berabags is an independent editorial site. It is not affiliated with, endorsed by or sponsored by any bag brand, retailer, airline or agency named on this page. This page contains no affiliate links; if berabags adds any in future they will be labelled. Rules and policies change, so check the linked source before you act. This is general information, not legal, medical or professional advice.