30 L or 40 L Travel Backpack - Which One to Buy
Choose 30 litres for the flat 180-degree opening and simpler packing on trips without bulky clothing. Choose 40 litres for capacity and vacuum compression when coats, fleeces or towels have to travel. The capacity figures overlap because compression changes what a litre holds.
Side by side
| Travel Backpack 30 L | Vacuum Backpack 40 L | |
|---|---|---|
| Capacity | About 30 L | 40 L |
| Dimensions | 43 × 30 × 20 cm | 40 × 30 × 20 cm |
| Compression | None | Built-in vacuum, over 50% on bulky items |
| Opening | 180°, lies flat | Main compartment |
| Trolley sleeve | 22 cm | Not published |
| Packing capacity | 4–6 days | 3–5 days |
| Laptop | Up to 15.6 in | Up to 15.6 in |
The figures that look wrong
The 40-litre bag is rated for fewer days than the 30-litre one, and it is shorter. Both are real and both have the same explanation. The day rating assumes the kind of trip each is built for: the larger bag is the one you take when bulky clothing is involved, and bulky clothing eats days. The three-centimetre difference in length matters only against a sizer, and there it works in the 40-litre model's favour: 40 by 30 by 20 is exactly the common European under-seat figure, which is what it was designed around.
Which constraint is deciding
If the constraint is convenience, take the 30-litre model. Nothing to seal, nothing to pump, and a panel that lies flat every time you open it. On a trip with several stops, that is worth more than volume.
If the constraint is volume in a cold month, take the 40-litre model. A coat and a fleece sealed and pumped give back more than half their space, and no amount of careful folding does that.
If the constraint is a gate sizer, the 40-litre model is the one whose dimensions match the common European box. Figures carrier by carrier are in the airline allowances.
Full specifications: Travel Backpack 30 L and Vacuum Backpack 40 L.
Questions
Is 40 litres too big for a carry-on?
It is the practical ceiling. Above 40 litres a backpack stops clearing cabin allowances on most carriers.
Why does the smaller bag cover more days?
Because the day ratings assume different trips. The larger bag is the one taken when bulky clothing travels, and bulk is what fills a bag.
Does the 40-litre model open flat?
The flat 180-degree opening is the 30-litre model's defining feature. The 40-litre model is built around compression instead.