The largest size that still costs nothing
Plenty of backpacks stop well short of the free allowance and leave litres unused. This one takes the limit: 40 x 30 x 20 cm is the exact figure Ryanair publishes for the personal bag included with every fare.
Every centimetre of the free allowance
Against a 40 x 20 x 25 cm pack, the depth is the same but the height rises to 30 cm. Volume goes up by roughly a fifth without ever leaving the allowance. On budget airlines it is the best capacity-to-free ratio in the range.
Packing that survives the journey
The 180° opening gives you the whole volume at once. The compression strap holds the stack of clothes in place in transit, which is what stops the bag slumping and spreading past the allowance after two connections.
The details that matter in transit
The Classic version has the same size and adds an external USB port.
A reinforced base and a sharper finish
The Premium version keeps the same interior layout but changes how it holds itself: a reinforced base so it stands upright when set down, a smarter-looking fabric, cleaner zip finishing. Worth it if the bag doubles as a work bag.
A separate laptop compartment
The laptop travels in its own compartment against your back, with pockets for the charger, cables and pens. It comes out on its own at security, without unpacking the rest.
A back pocket nobody can reach
Flat against your back, this pocket stays out of reach while the bag is on your shoulders. It is the obvious place for a passport, a phone or boarding passes on a crowded train.
A strap for your suitcase handle
A strap crosses the back of the bag and slides over the telescopic handle of a wheeled case. The bag stays put and your hands stay free in the terminal.
What the airlines allow
At 40 x 30 x 20 cm this pack sits inside the free personal bag allowance of the main budget airlines, and inside the cabin bag allowance of the full-service carriers.
| Airline | Stated allowance | Category | KLOSTAIN Premium 24 L |
|---|---|---|---|
| Ryanair | 40 x 30 x 20 cm | Free personal bag | ✓ Within it |
| easyJet | 45 x 36 x 20 cm | Free personal bag | ✓ Within it |
| Jet2 | 40 x 30 x 20 cm | Free personal bag | ✓ Within it |
| Wizz Air | 40 x 30 x 20 cm | Free personal bag | ✓ Within it |
| Vueling | 40 x 30 x 20 cm | Free personal bag | ✓ Within it |
| Eurowings | 40 x 30 x 25 cm | Free personal bag | ✓ Within it |
| British Airways | 56 x 45 x 25 cm | Cabin bag | ✓ Within it |
| Lufthansa | 55 x 40 x 23 cm | Cabin bag | ✓ Within it |
Dimensions and weight as stated by the manufacturer. Baggage rules change: always check the size printed on your own booking before you fly.
Staying within the sizer to the gate
When you use the maximum size there is no margin left, and that is the one thing to watch with this format. Pack flat, tighten the strap before you close it, and resist pushing a rolled jacket into the front pocket as you reach the gate.
This colour, and the others
A plain mid grey: neutral, discreet, and it ages without dating.
The same pack comes in 6 colours. The others:
Full specification
Dimensions and weight as stated by the manufacturer. Baggage rules change: always check the size printed on your own booking before you fly.
| Dimensions | 40 x 30 x 20 cm |
|---|---|
| Volume | 24 litres |
| Laptop compartment | Up to 15.6″ |
| Stated weight | 900 g |
| Colour | grey |
| Opening | 180°, lies flat like a case |
| Material | High-density polyester, water-resistant layer |
| Carrying | Padded back, wide adjustable straps, chest strap, reinforced handle |
| Fittings | Suitcase strap, anti-theft back pocket, reinforced base, compression strap |
The three sizes in the range
Same build, three sizes. Which one is right depends mostly on the airline you fly.
| 20 L · 40x20x25 | 24 L · 40x30x20 | 30 L · 45x36x20 | |
|---|---|---|---|
| Best for | Ryanair, Jet2, weekends away | Max free size on Ryanair, Jet2 | easyJet, week-long trips |
| Trip length | 2 to 4 days | 3 to 5 days | 4 to 6 days |
| Laptop | 14″ | 15.6″ | 15.6″ |
| See the 20 L | You are here | See the 30 L |
Common questions
Before ordering, check the size, the colour, the seller and the delivery and returns terms shown on the retailer’s page.
Is 40 x 30 x 20 really free on Ryanair?
It is the maximum size Ryanair publishes for the personal bag included with every fare, raised from 40 x 30 x 15 cm in September 2025. Jet2 and Wizz Air allow the same. Close the straps so the bag holds its shape.
How many days does it hold?
Three to five days depending on how you pack. It is the best compromise in the range between real capacity and flying free.
How is it different from the 20 litre?
Ten centimetres more height, for roughly a fifth more volume. The 20 L keeps a margin against the sizer; the 24 L uses all of it.
Will a laptop fit?
Yes, in a separate sleeve with pockets for the charger and cables. The screen size it takes is in the specification table.
What happens if it fails at the gate?
The bag is then treated as a cabin bag and charged at the airport rate, which is far higher than booking online. Which is why packing flat and tightening the strap matters.
Made from a strong seeming fabric. Lots of pockets for papers, books, ipad etc. It holds a lot so I can make full use of the underseat allowance on Ryanair.
I am happy with it.