One-bagging Europe for three weeks — is 40L overkill now that the personal item rules are changing? Bag Question

Three weeks in 26L, twice. It is absolutely sink laundry every three or four days. Four shirts, two bottoms, one warm layer, one shell, and that's it. The thing that makes it work is not the bag, it's deciding you're genuinely fine washing socks in a hostel bathroom. If that sounds miserable rather than neutral, take the 40L and pay a gate fee twice — it's cheaper than three weeks of resenting your own decision.

Do not plan a September trip around the new rule. The reform was approved in July 2026 and the reporting has it entering into force in 2027, pending formal adoption — so for this trip you are on each airline's published dimensions, which still vary a lot. Print the allowance for all five carriers, find the smallest one, and buy to that. That's a boring twenty minutes that saves you a gate argument.

A 40L that genuinely compresses is the compromise I landed on — mine goes on as a personal item when it's half empty and as a cabin bag when it isn't, and it cost about $180. The trap is that a soft 40L will happily swallow 45L of stuff and then it fits nothing. If you buy the bigger one, put a rule on yourself: it travels half empty on the outbound.

Counterpoint to the 26L crowd: I did 22 days in 30L and the thing I'd change isn't the capacity, it's the opening. Get a clamshell that lies flat, not a top-loader. I wasted an enormous amount of the trip digging for the thing at the bottom, and no amount of packing cubes fixes a bad opening.

If you're carrying camera gear none of this applies and the maths changes completely. Two bodies and three lenses is a 30L problem before you've packed a single shirt.