Will a 40L backpack count as a personal item?

No, a 40L is almost always a carry-on. A personal item must fit under the seat in front of you, which usually limits you to 20–25 liters.

Do I need a bigger pack for winter travel?

Yes, bulky layers take up space. Either wear your heaviest coat and boots on the plane or use a compression sack to shrink your fleece and thermal layers.

Choosing the Right Backpack Size for Your Trip

For most trips, a 40-liter backpack is the sweet spot because it fits in almost all airline carry-on overhead bins. If you are traveling for longer than two weeks or need specialized gear, move up to 50 or 60 liters, but remember that you will have to check it at the gate.

Define your trip duration. If you are traveling for 1–7 days, a 30-liter pack is sufficient. For 1–4 weeks, aim for 40 liters. For anything over a month, choose a 45–50 liter pack, assuming you plan to do laundry along the way.
Check airline carry-on dimensions. Most international airlines limit carry-ons to 56cm x 36cm x 23cm. Before buying, verify that your pack’s dimensions fit these limits so you don't get forced to pay checked bag fees at the gate.
Prioritize a suspension system. If your pack is over 35 liters, ensure it has a hip belt and an adjustable torso length. This transfers weight from your shoulders to your hips, which is essential for walking more than 15 minutes between transit and your accommodation.
Perform a 'dry run' pack. Pack your gear, put on your shoes, and walk around your neighborhood for 30 minutes. If your back hurts or the straps dig into your shoulders, the pack is either too large, ill-fitted, or overloaded.

Will a 40L backpack count as a personal item?: No, a 40L is almost always a carry-on. A personal item must fit under the seat in front of you, which usually limits you to 20–25 liters.
Do I need a bigger pack for winter travel?: Yes, bulky layers take up space. Either wear your heaviest coat and boots on the plane or use a compression sack to shrink your fleece and thermal layers.