There is no single airline baggage rule to memorize. Your allowance varies by airline, cabin class, elite status, ticket type, and even the origin and destination of the flight — and a connection can change it again. The one habit that never fails: read the baggage conditions printed with your ticket before you pack.
Still, the industry has reference points. Here is how checked and carry-on rules differ, what the standard numbers are, and how the two counting systems work.
This article is general information, not travel or legal advice for a specific trip.
Two bags, two sets of rules
Airlines treat checked and cabin luggage differently, per the Wikipedia article on baggage allowances. The hold bag is judged mainly by weight: it gets weighed at check-in, and if it runs over the limit you will hear about it on the spot — the classic fix is moving items to another bag or carrying them on. The carry-on is judged primarily by size, measured by dimensions or by total linear measurement: length plus width plus height.
The reference numbers worth knowing
The International Air Transport Association publishes recommendations that many carriers lean on. For checked bags, the advised maximum weight is 23 kg against a hard limit of 32 kg, with an advised size of 158 cm in linear dimensions and a 203 cm cap — the lower weight figure exists because of health and safety rules, according to Wikipedia. For cabin bags, a 2015 IATA recommendation set a maximum of 55 by 35 by 20 centimeters; bags that fit can carry an "IATA cabin OK" logo, and since that figure is tighter than most airline limits, such bags are practically allowed everywhere, per the same source.
Europe runs on a rough consensus: European carriers follow a similar cabin size limit of 22 by 16 by 8 inches — 56 by 41 by 20 centimeters — with cabin weight limits between 15 and 22 pounds, though the actual limits vary by airline, per Wikipedia's summary. The lesson: a bag that satisfies one European airline usually satisfies the region, but the scales are the final word. For related coverage, see TSA PreCheck vs. Global Entry vs. CLEAR: What Each One Actually Skips.
Piece or weight: the two counting systems
Under the Piece Concept, you check a set number of suitcases, each weight-capped — up to 23 kg in economy and up to 32 kg in business or first, per the Wikipedia summary — with the count and the cap set by airline, class, status, ticket type, origin, and destination. This system applies to passengers traveling to or from the Americas; Vietnam Airlines adopted it from 1 August 2019, according to the source. Under the Weight Concept, you get a total weight to spread across as many bags as you like, and groups traveling together can often pool their allowances.
Where the money comes in
Baggage is also a business line. The 23 largest US airlines reported 4.6 billion dollars in baggage fees in 2017, a figure that reached 33 billion dollars in 2023 — an increase of 15 percent over the prior year — per the source's tally. Fees have long been the norm among US carriers and were predicted to spread to low-cost trans-Atlantic tickets and then globally. In Europe, consumer groups and lawmakers have pushed back against carriers charging for hand luggage, arguing for standardized carry-on dimensions and fees across EU airlines. The direction is clear: what used to be included now tends to be priced, so check whether your fare bundles a bag at all. This connects to our earlier piece, Do You Need a Visa for a US Business Trip? The ESTA and B-1 Rules, Fees, and Timing.
The personal item and the small print
Beyond the roller bag sits the small personal item — a purse, backpack, or laptop bag — and its rules are exactly as variable as everything else on this page. Treat every cabin piece as sized and counted, check that your fare includes it, and measure the bag at home rather than discovering the sizer at the gate. When flights connect, remember that a ticket can carry different limits per segment, including when one leg is long-haul.
Conclusion: read your ticket, weigh your bag
Baggage allowances look chaotic until you see the structure: hold bags are ruled by weight, cabin bags by size, and every figure shifts with airline, class, fare, and route. Anchor on the conditions in your ticket, borrow the IATA reference numbers as a sanity check, weigh everything at home, and treat any bundled bag as money you already spent. That is the whole game.
