Baggage Knowledge
Whose baggage rules apply when two airlines carry you
For a multi-airline checked journey, start with the allowance disclosed on your ticket or itinerary receipt. IATA Resolution 302 normally selects one carrier's published provisions using a documented sequence; if the relevant carriers have not published rules, the sequence can ultimately fall back to each operating carrier's rules sector by sector.
- Start with the baggage allowance printed on your own ticket or itinerary receipt, not on the airline you searched last.
- IATA Resolution 302 picks one "Most Significant Carrier" through a documented sequence when airlines disagree.
- On a codeshare, the Marketing Carrier’s policy usually wins unless it says the Operating Carrier’s applies instead.
- If your itinerary touches the US or Canada, national law overrides all of this: the first-coupon Marketing Airline governs.
My two airlines show different baggage allowances. Which one applies?
Neither website is necessarily wrong: each may describe that airline's general policy rather than the provisions selected for your ticketed itinerary. IATA's interline guidance says the applicable provisions come from regulation, a bilateral agreement, or the default Resolution 302 sequence.
Read the allowance disclosed on your itinerary receipt or e-ticket first; if it is missing or unclear, ask the booking source or carrier to identify the applicable provisions.
How does the industry decide which airline's rules win?
Resolution 302 first applies shared rules when all participating carriers publish the same provisions. If their published rules differ, it applies the Most Significant Carrier's published provisions; the MSC is generally identified from the first geographic boundary-crossing sector.
If the MSC has not published baggage rules, the sequence falls back to the check-in carrier and can ultimately apply each operating carrier's rules sector by sector.
Begin with the rule disclosed for the ticketed itinerary
An airline's general baggage page may not show the provisions selected for your ticketed itinerary. IATA's guidance says the applicable provisions may come from government regulation, a bilateral agreement between carriers, or the default Resolution 302 process.
The practical starting point is the allowance disclosed when the booking is confirmed and stored or shown on the itinerary receipt or e-ticket. This is usually an itinerary-level answer, but Resolution 302 includes a final sector-by-sector fallback when neither the Most Significant Carrier nor the check-in carrier has published rules.
How the Most Significant Carrier is actually chosen
Resolution 302 starts by checking whether the participating carriers publish the same baggage rules. If they do, those shared rules apply.
Where they disagree, the resolution reaches for geography. IATA divides the world into Traffic Conference Areas: TC1 covers the Western Hemisphere (the Americas and the Caribbean), TC2 covers Europe, the Middle East and Africa, and TC3 covers Asia and Asia Pacific. The Most Significant Carrier is generally the airline operating the first flight segment that crosses from one of these areas into another.
For journeys that stay within one area but cross a sub-area, it is the first segment crossing that sub-area boundary; for journeys within a single sub-area, it is the first international segment.
If the MSC has not published baggage provisions, the sequence does not stop: it uses the check-in carrier's published provisions. If that carrier has not published them either, each operating carrier's rules apply sector by sector. Price does not determine the MSC, and codeshare or regulatory rules can alter which carrier's provisions govern.
Reading the number correctly once you have the right airline
Even the governing allowance can be expressed two different ways, and mixing them up is its own source of confusion. IATA recognises two standard concepts: the Weight Concept, where your allowance is a total weight such as 20 kg or 45 lb, and the Piece Concept, shown as PC, where your allowance is a number of bags rather than a weight.
Some carriers combine them — for example, two pieces with a combined limit of 32 kg.
Airlines are recommended to disclose their allowance through ATPCO's shared database, which many airline systems use when determining excess, oversize and overweight charges and embargoed items. IATA also says baggage information should be disclosed when the booking is confirmed, commonly on the passenger itinerary receipt, and may be stored in the e-ticket record.
What to actually check before you pack
The determination is intricate, so use the booking record and a direct clarification rather than trying to reverse-engineer it from two general policy pages:
- Read the baggage allowance disclosed on your itinerary receipt, e-ticket or booking confirmation before consulting a general airline policy page.
- If your trip starts or ends in the US or Canada, that regulatory rule overrides the geographic method: check the Marketing Airline on your first ticket coupon.
- On a codeshare flight, start with the Marketing Carrier's policy and only look at the Operating Carrier's if the Marketing Carrier explicitly defers to it.
- Confirm whether your allowance is weight-based or piece-based before you pack, since packing to the wrong concept is a common way to arrive at the airport already over the limit.
- When the allowance is absent or ambiguous, ask the booking source or carrier to identify the provisions for the checked portion before travel.
FAQ
Does the cheaper airline's baggage rules apply if I paid less for that leg?
No. Price paid does not enter into Resolution 302's determination. The Most Significant Carrier is chosen by which airline operates the flight segment that crosses a geographic boundary, regardless of fare.
What if my whole trip is with airlines that publish identical baggage rules?
Then there is nothing to resolve: IATA's guidance states that when published rules are the same across all carriers on the itinerary, those shared rules simply apply, and the Most Significant Carrier question does not arise.
Can two airlines just agree privately on whose rules apply?
Yes. Bilateral agreements can select the applicable baggage provisions instead of the default Resolution 302 sequence. Because a traveller may not be able to inspect such an agreement, use the allowance disclosed for the booking and request clarification when it is missing or ambiguous.
Sources
- IATA: Interline Considerations on Baggage Standards (Resolution 302, Most Significant Carrier) (checked 2026-08-19)
This article states the baggage-selection sequence in IATA's interline guidance, including its unpublished-rule fallback. Regulations and bilateral agreements can replace the default sequence. The booking source and carriers remain responsible for disclosing and clarifying the applicable allowance; this page is explanatory, not a baggage entitlement.
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Mubboo Flights Editorial · Reviewed by mubboo-editorial-review (2026-08-20)