A "cabin size" label on a bag listing is the seller's claim, not a rule. The limit that counts is your airline's. This guide covers what the airline trade body IATA says about carry-on bag sizes, so you can check a bag before you buy it. It is general information: allowances change, so confirm them with your airline.

This guide is based on the public source listed below. We have not tested any bag or store. Our guides to choosing a handbag or backpack and liquids in hand luggage cover related points.

What IATA says

Source: IATA, Passenger Baggage Rules page (shows a 2026 copyright and mentions a June 2026 event, but no explicit date). Last checked: 17 October 2026.

  • Airlines set their own rules. IATA develops baggage rules and standards for the industry, but each airline sets its own allowances and conditions of carriage. National regulations govern security screening.
  • A typical size. Many airlines use a maximum of 56 × 45 × 25 cm (22 × 18 × 10 inches). IATA presents this as a general reference only.
  • A typical weight limit. Some airlines also set a weight limit, often starting at 5 kg (11 lb).
  • Wheels and handles count. The size limit includes wheels and handles.
  • Allowances vary by airline, cabin class and aircraft type, so confirm them before you travel.

How to check a bag listing

  1. Find the outside dimensions, including wheels, handles and side pockets. If a listing gives only the inside size, ask the seller for the outside size.
  2. Compare with your airline's published limits for your fare, cabin class and aircraft, not with a typical size. Budget fares often have tighter limits.
  3. Check the empty weight. A heavy bag leaves less for your things if your airline caps weight.
  4. Allow a margin. Bags that are packed full can bulge beyond the stated size.
  5. Read the return policy before you order, because used luggage is often not returnable.
  6. Plan the contents. Liquids in carry-on follow separate rules (see our liquids guide), and power banks must go in the cabin under UK CAA rules (see our Compare table).

What we could not confirm

  • The IATA "Cabin OK" size, which we could not read, and the limits of any particular airline.

Source: IATA, Passenger Baggage Rules.