“Cabin size” is not a universal standard. Check the current allowance for every operator on the route and compare it with the bag’s external measurements, including wheels, handles, feet and overfilled pockets. Allow a margin rather than assuming a soft bag can always be compressed.

Capacity figures are useful for comparison only when brands measure them consistently. A rectangular opening and a simple interior may hold more usable clothing than a larger quoted volume broken up by wheel housings and curved panels.

Every kilogram used by the bag itself reduces what can be packed within a weight limit. A very light case may save allowance but still needs sufficient structure, reliable handles and wheels that suit the surfaces expected. Compare the whole design rather than treating the lowest weight as automatically best.

• Wheels: attachment, protection from impact, replaceability and performance on uneven ground.
• Handles: wobble, grip comfort, lift handles on more than one side and the way the telescopic handle affects interior space.
• Zips and closures: smooth operation, lock compatibility, weather exposure and whether expansion creates strain.
• Seams and fabric: reinforcement at straps and handles, abrasion resistance and realistic water resistance.
• Harness: torso fit, shoulder shape, hip-belt usefulness, ventilation and the ability to hide straps during transport.

Clamshell openings make a backpack behave more like a suitcase. Top-loading designs can be simple and weather resistant but may require unpacking to reach lower items. External pockets are useful only when they do not invite overfilling or expose important items.

Use organisers to support the bag, not to compensate for the wrong bag. See Packing Essentials for a simple system.

Read the actual warranty rather than relying on the word “lifetime”. Check what is covered, who pays postage, whether proof of purchase is required, whether wheels and handles are replaceable, and whether service is available in the country where you live. A repairable mid-priced bag can offer better long-term value than a premium model with difficult support.

1. What is the smallest size and weight limit on the route?
2. How far will the bag be carried, rolled or lifted?
3. Will stairs, cobbles, sand, boats or small vehicles be common?
4. Can you test the fit or return the bag after loading it at home?
5. Which failure would disrupt the trip most?
6. Can the main wear parts be repaired or replaced?

Use the full travel gear buying framework to compare shortlisted bags consistently.