Do airline alliances share a personal-item rule? We compared Star, Oneworld and SkyTeam

Short answer: alliances do not harmonise personal-item sizes. Within Star Alliance our sample spans 15 cm (Lufthansa, SWISS) to 22.9 cm (United). Oneworld runs 15 cm (British Airways, Iberia) to 20.3 cm (American). SkyTeam is a uniform 15 cm (Air France, KLM). The tightest number in each alliance is still 15 cm — so a 14 cm-deep bag clears them all.

Alliance membership, local rules

A frequent-flyer alliance is a marketing and network agreement. Baggage rules stay with the operating carrier. We grouped the carriers we track by alliance and looked at the spread.

Alliance	Carriers in our set	Depth range	Share clearing 15 cm
Star Alliance	Lufthansa, SWISS, United, ANA*, Condor	15 – 22.9 cm	2 of 4 published (50%)
Oneworld	British Airways, Iberia, American	15 – 20.3 cm	2 of 3 (67%)
SkyTeam	Air France, KLM	15 cm (both)	2 of 2 (100%)

*ANA publishes no personal-item size (under-seat test only).

The useful takeaway

If you fly one alliance exclusively, the relevant number is still the operating carrier's, not the alliance's. But the floor is consistent: every alliance contains carriers at 15 cm, and none goes below it. A bag that clears 15 cm clears the strictest member of every alliance we looked at.

Where alliances actually help

The value of alliance status is lounge access and priority handling, not baggage leniency. Don't assume your Star Alliance gold card widens the sizer — it does not. The 25 × 17 × 14 cm bag's edge is that its 14 cm depth is below the alliance floor, so status is irrelevant to whether it fits.

Should you buy the Jelkin 25 for this?

Alliance status does not widen the sizer — but every alliance in our set has a 15 cm floor, and none goes below it. A 14 cm-deep bag therefore clears the strictest member of Star, Oneworld and SkyTeam alike, which means you can switch carriers without switching bags. That is the reason to buy it if your flying is spread across alliances.

How to check this yourself before you fly

1. Look up the operating carrier, not the alliance you hold status with. Baggage rules stay with the airline that flies the plane.
2. Take the strictest member's number as your working limit. In Star Alliance that is 15 cm (Lufthansa, SWISS), not United's 22.9 cm.
3. Measure depth packed. Status, lounge access and priority boarding change nothing about the sizer.
4. If a carrier in your mix publishes no number at all (Delta, ANA, JAL), fall back to the under-seat test and keep the bag visibly shallow.

Keep reading:

• airline personal item size checker — all 19 carriers side by side
• one-centimetre depth cliff — why 15 cm decides six airlines
• the 25 cm bag that fits every sizer — length-vs-depth end to end
• why external dimensions lie about capacity — how we measure bags
• Jelkin 25 — the 25 × 17 × 14 cm bag measured on this page