Two bags, no add-on

British Airways includes both an underseat bag and a full cabin bag on every fare, with nothing to buy at booking. Among UK carriers that is genuinely generous, and it changes which case you should buy.

The cabin allowance is 56 × 45 × 25cm with a 23kg limit. That 23kg figure is the one worth noting: most low-cost carriers cap cabin bags at 10kg, so a hard-shell case that would be too heavy elsewhere is comfortable here.

The underseat allowance is unusually shallow

British Airways sets its underseat bag at 40 × 30 × 15cm. At 15cm deep it is shallower than any wheeled case — a wheeled hard-shell needs around 20cm before you have packed anything.

That allowance is designed for a laptop bag, handbag or slim rucksack. It is not a suitcase allowance, and no ATX case fits it. We would rather say so than sell you something that will be refused.

Buy for the cabin allowance instead

Since the 56 × 45 × 25cm cabin bag is included free, that is the allowance to buy for. It takes a full cabin suitcase, and the 23kg limit means you can pack it properly.

If the lockers fill

British Airways will place your cabin bag in the hold free of charge if overhead space runs out. Pack anything valuable, fragile or essential — medication, documents, chargers — in your underseat bag so it stays with you.