Somewhere between your third and fourth browser tab, every 40-litre travel pack starts to look like the same bag photographed at different angles. The descriptions use the same words, the feature lists overlap, and the differences that decide whether a bag suits you are buried in how it opens and how it carries.

This list exists to shorten that decision. It covers five packs in the 40-litre class that are widely sold and widely discussed, and it sorts them by the kind of trip each one fits rather than by an overall winner. Because there is no overall winner. There is only the bag that matches how you pack, how far you walk and whether you are carrying a camera or a laptop.

One thing to be clear about before the list: nothing here is ranked by a score, and no pack has been through any kind of laboratory. The comparisons below are drawn from published specifications and from how the designs are meant to work, which is enough to tell you which bag suits which trip.

How this list was assembled

The criteria were chosen to reflect the decisions travellers actually face, then applied evenly across every pack on the list.

1. Availability. Every pack had to be widely sold through mainstream retailers, so that replacement parts and repairs are realistic rather than theoretical.
2. Layout and access. How the bag opens, whether you can see the contents at once, and whether there is a sensible place for a laptop or a camera.
3. Carrying comfort as designed. Hip belt, strap design and whether the harness stows for a flight — judged from published specifications, not from wearing the bag.
4. Usable volume. Not the number in the product name, but how much structure and padding sits between you and your clothes.
5. Honest downsides. Any pack that could not be paired with a clear reason not to buy it was left off the list.

Two 40-litre-class bags were deliberately excluded: the lightweight hiking packs and the ultra-cheap generic travel packs. The first group carries beautifully and organises badly for city travel; the second group tends to fail where the first group excels, at the harness and the zips.

The five packs at a glance

The picks, one at a time

Osprey Farpoint 40: best for a first one-bag trip

The Farpoint 40 is the pack people are pointed toward when they ask what to buy, and the design justifies the reputation. Published specifications describe a 40-litre panel-loading main compartment, front daypack attachment points and a padded laptop sleeve. Nothing about it is clever, which is exactly the appeal: it opens flat, it holds clothes, it closes.

It suits travellers doing one to three weeks with carry-on only, and anyone who wants a panel-opening bag that is easy to live out of. Because it is so widely sold, replacement parts and repairs are easier to arrange than for a niche pack.

Why you might not buy it: it is not the lightest option in its class, and the harness is simpler than what a hiking-focused pack offers. If you are flying carriers that weigh cabin bags, or you plan multi-hour walks with the bag loaded, that combination of weight and a basic harness is a real limitation. Check current price at REI.

Cotopaxi Allpa 35L: best for organised packers

The Allpa 35L assumes you want a place for everything and would rather not dig. Published specifications list a clamshell opening with mesh dividers, suitcase-style carry handles on several sides and a rain cover included. It opens flat like a suitcase, which transforms a cramped guesthouse room into a workable packing surface.

It suits travellers who like compartments for small items and itineraries that mix city days with short hikes, where the bag comes off and on frequently.

Why you might not buy it: the structured build feels heavier on long walking days, and the compartment walls eat usable volume. If you are a stuff-it-all-in packer, or your priority is space per litre, the dividers will frustrate you more than they help. Check current price.

Peak Design Travel Backpack 45L: best for camera-carrying travellers

This is the pack for the traveller who needs one bag to be two. Published specifications describe a compression system that shrinks the bag for day use, side access panels and a weather-resistant shell, plus an accessory ecosystem built around camera gear. The compression system is the point: the bag expands and contracts without a full repack, so it can be a large travel bag on the flight and a smaller day bag at the destination.

It suits photographers who need a bag that converts, and trips where the bag has to double as a day pack.

Why you might not buy it: the outlay is high for a nylon bag, and the empty weight is noticeable before you put anything in it. If you are not carrying camera equipment, you are paying for a system you will not use. Check current price.

Aer Travel Pack 3: best for business-leaning travel

The Aer Travel Pack 3 is the one that does not look like a backpacking bag. Published specifications list a shoe compartment, a structured laptop section and compression straps. The shoe garage is the detail that earns its keep on mixed trips: dirty soles stay away from shirts, and the structured laptop section means you can walk into a meeting without a second bag.

It suits work trips with a laptop and a change of clothes, and travellers who want a bag that looks at home in an office.

Why you might not buy it: usable capacity is smaller than the litre count suggests, because the structure that makes it presentable also occupies interior space, and the colour range is limited. If you need every litre, this is the wrong trade. Check current price.

Eagle Creek Migrate 40L: best value duffel-style pack

The Migrate 40L is the pragmatic option: a duffel-shaped bag with backpack straps that can be stowed. Published specifications list convertible backpack straps, a recycled fabric body and lockable zippers. It costs far less than comparable travel packs, which matters if you are buying your first one-bag setup and would rather spend the difference on the trip.

It suits budget-conscious one-bag travellers and trips where the bag gets thrown into a bus hold or a car boot.

Why you might not buy it: it has fewer internal organisation features, and the softer structure means it slumps when it is only half full. If you want the bag to stand up on its own and keep its shape, spend more. Check current price.

Who should buy which

Match the scenario to the pack rather than the other way around.

1. First one-bag trip, no strong opinions yet — the Osprey Farpoint 40 is the safest place to start.
2. You like compartments and unpack into drawers — the Cotopaxi Allpa 35L fits that habit.
3. You carry a camera and want the bag to shrink for day use — the Peak Design Travel Backpack 45L is built around that need.
4. You arrive and go straight to a meeting — the Aer Travel Pack 3 looks and behaves accordingly.
5. You want the lowest outlay and mostly short carries — the Eagle Creek Migrate 40L covers it.

If you are still unsure which of those five scenarios describes you, the decision framework in the carry-on travel backpack buying guide works through the trade-offs in more detail.

What you give up in a 40-litre-class pack

Buying in this size band means accepting trade-offs that no brand can design away.

• Cold-weather clothing. A 40-litre bag that handles two weeks of warm-weather travel becomes tight the moment you add a coat, a fleece and boots.
• Camera systems. A body plus two lenses consumes space that clothing would otherwise use, which is why the convertible packs exist.
• Souvenirs. Anything you buy on the road competes with what you brought, unless you post it home or plan to leave items behind.
• Comfort at full weight. These are travel packs, not load haulers. Walk an hour with one fully loaded and you will feel the difference from a proper trekking pack.
• Laundry avoidance. A pack this size only works if you are willing to wash clothes or use a laundry service during the trip.

The volume squeeze is also why the contents matter as much as the bag. Cubes that hold their shape let you pack the same clothing into less space, and the packing cubes that survive real trips guide explains which styles help and which add bulk.

Frequently asked questions

Is a 40-litre pack too big for carry-on?

It depends on the airline, not on the number. Volume limits are only part of the story: carriers publish height, width and depth limits, and a bag can be under the volume figure while still exceeding a specific dimension. Packs in this class are commonly used as carry-on, but confirm your airline’s current limits before you go, especially on fare types that allow only a personal item.

How many days of clothing fit in a 40-litre travel backpack?

Roughly one to three weeks for most travellers, depending on climate. The working assumption is that you will do laundry once a week rather than pack for every day. Warm destinations with light clothing are straightforward; cold trips with bulky layers are where the same bag suddenly feels small. Packing the same clothing into cubes usually buys back a little space.

Should I choose a 35-litre or a 40-litre pack?

Choose the smaller bag if you fly carriers with tight cabin allowances, or if you know you overpack and want a hard limit built into the bag. Choose the larger one if you travel with layers, camera gear or a laptop, or if you want room left for anything you buy on the road. The five litres difference is smaller in practice than the difference between a clamshell and a panel opening.

Are these packs waterproof?

No. Weather-resistant shells and included rain covers handle rain during a walk between a station and a guesthouse, which is the realistic scenario for most travel. They are not submersible and they are not designed for hours of exposed rain. If you are travelling in a monsoon season or by boat, add a dry sack for electronics rather than relying on the bag alone.

Does the harness matter if I only walk short distances?

Less than you would think, which is why convertible duffels sell so well. If your bag goes from a taxi to a hotel room and back, a simple harness is enough, and the stowable straps that protect against snagging matter more. Once your carries stretch past half an hour, the hip belt and strap design become the most important thing about the bag.

The bottom line

If you want one recommendation, the Osprey Farpoint 40 is the pack that suits the widest range of first one-bag trips: predictable layout, widely available, easy to repair or replace. The most common runner-up scenario is the Cotopaxi Allpa 35L, which wins on organisation and loses on usable volume — the trade that defines it.

Everything else on this list is a fit question rather than a quality question. Buy the Peak Design Travel Backpack 45L if the bag has to convert for camera gear, the Aer Travel Pack 3 if it has to look professional, and the Eagle Creek Migrate 40L if the budget is better spent on the flight. Then confirm your airline’s carry-on limits, because that is the one constraint no bag choice can fix.