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How to Compare Baggage Rules Across Airlines
Manesh Jayawardhana
CIO & Co-founder
Your bag cleared the sizer in London. In Frankfurt, connecting onto a different carrier, it’s two kilograms over and the gate fee is more than the second flight cost.
Baggage rules are per-carrier, they vary more than anyone expects, and the rule that catches people is which carrier’s applies on a connection.
Which carrier’s rules apply
Generally the operating carrier for each leg, which isn’t always the airline whose name is on the booking. Codeshare flights are sold by one airline and operated by another, and the operator’s baggage rules apply.
On a single ticket, some alliances and interline agreements apply the first carrier’s allowance throughout the journey. Sometimes. It depends on the agreement, the alliance, and occasionally on the direction of travel.
On separate tickets, each leg is independent. Your bag is checked in again, sized again, weighed again, and the second carrier’s rules apply with no reference to the first. This is the case that costs people money, and it’s increasingly common as travellers self-connect to save on fares.
The safe approach: identify every operating carrier on the itinerary and plan to the strictest of them.
| Booking | Whose rules | Risk |
|---|---|---|
| Single ticket, one carrier | That carrier | Low |
| Single ticket, interline | Often the first carrier | Check — varies |
| Separate tickets | Each leg independently | Highest |
| Codeshare | The operating carrier | Often surprises |
Dimensions include everything
Sizers measure the bag as it is. Wheels, handles, external pockets and anything strapped to the outside all count.
A bag advertised as “cabin size” is frequently measured without wheels, or at its nominal empty dimensions before anything is packed. A soft bag that’s within limits empty can fail once full, because it bulges.
The practical test: if the bag doesn’t drop into the sizer under its own weight, it’s over. Pushing it in doesn’t count, and gate staff know exactly what that looks like.
Weight limits vary more than size
Cabin weight limits differ enormously — some carriers barely check, some enforce strictly, and the permitted figure varies by a factor of two or more between airlines on the same route.
Low-cost carriers in particular tend to have strict cabin limits, tightly enforced, and gate fees priced to discourage.
The pattern worth knowing: a bag that’s fine everywhere on the outbound can fail on the return, if the return is with a different carrier.
Pre-pay rather than pay at the gate
Gate baggage fees are typically much higher than pre-paid checked baggage — often several times higher — and paying at the gate happens under time pressure, sometimes in a queue, occasionally with payment method restrictions.
If you suspect you’re close to the limit, pre-paying online is nearly always cheaper. The exception is where you’re confident and the pre-pay fee is substantial, which is a gamble with known odds.
Common mistakes to avoid
- Assuming the first carrier’s allowance applies throughout a multi-carrier itinerary.
- Measuring a bag empty.
- Forgetting that personal items have their own size limits, which are also enforced.
- Booking separate tickets to save money without checking the second carrier’s baggage rules.
- Discovering the limit at the gate, where the fee is highest and the options fewest.
How to do it with Baggage Allowance Comparison
The Baggage Allowance Comparison compares limits across every carrier on the trip.
- List every operating carrier, including codeshare operators.
- Enter your bag’s real dimensions with wheels and handles, and its packed weight.
- Plan to the strictest allowance on the itinerary.
- Pre-pay for checked baggage if you’re anywhere near a limit.
Each airline’s own site is the authority on its current rules, which change. Other travel tools are in the tools directory.
Frequently asked questions
Which airline’s rules apply on a connecting flight?
Generally the operating carrier for each leg, though a single ticket sometimes applies the first carrier’s allowance throughout. On separate tickets, each leg’s rules apply independently.
Do dimensions include wheels and handles?
Yes, almost always. Sizers measure the bag as it is, and a bag advertised as cabin-sized can fail once its wheels and external pockets are included.
Why is being checked at the gate worse?
Because gate fees are typically much higher than pre-paid checked baggage, and payment at the gate is stressful and sometimes restricted. Pre-paying is nearly always cheaper.
Final thought
Find the strictest carrier on your itinerary and pack to that. The first airport tells you nothing about the sizer waiting at the connection.