Carry-on versus personal-item limits
Decide whether the bag is meant to be your main cabin luggage or the smaller companion item. That determines which airline allowance matters. Request external measurements and check how filled pockets affect the shape. A capacity figure alone cannot establish that one bag meets both roles across different carriers.
Clothing access during the trip
Think about whether you unpack on arrival or live from the backpack during the trip. Inspect the main compartment opening and any internal divisions accordingly. Pack shoes and toiletries in the intended arrangement, then check that the items you need during transit remain reachable without disrupting the clothing layer beneath them.
