A 40 × 30 × 20 cm backpack sounds compact on paper. However, dimensions alone do not really tell you whether you can use one for a weekend away, a four-day city break or even a five-day trip.
The more useful question is simple:
What can you actually fit inside one?
To find out, we packed the LEVARE Travel Backpack with the kind of clothing, technology, toiletries and everyday essentials we would realistically take on a short trip.
The result surprised us. With sensible packing and proper organisation, a 40 × 30 × 20 cm backpack can carry considerably more than its dimensions might suggest.
In this guide, we will show you what we fitted inside, where we stored everything and how you can make better use of a compact travel backpack without simply forcing more into the bag.
Why 40 × 30 × 20 cm?
For travellers trying to avoid taking a large suitcase, compact cabin luggage can make a journey considerably simpler.
A rectangular 40 × 30 × 20 cm travel backpack gives you a useful balance between packing space and portability. In particular, the relatively square shape means more of the internal space can be used for folded or rolled clothing rather than being lost around curved edges.
However, airline allowances are not universal.
For example, easyJet currently allows each passenger one small cabin bag measuring up to 45 × 36 × 20 cm, which must fit under the seat in front.
The UK Government also advises passengers to check directly with their airline for the number and size of bags they can take on board.
Therefore, although a 40 × 30 × 20 cm backpack may work within many cabin or personal-item allowances, always check the current rules for your specific airline, fare and route before travelling.
Our real 40 × 30 × 20 cm packing test
Rather than estimating capacity, we tested the LEVARE backpack ourselves.
In the main clothing area, we were able to pack approximately:
- 4 T-shirts
- 4 pairs of trousers
We then used the remaining sections of the backpack for:
- 2 sets of pyjamas
- 5 sets of underwear
- 5 pairs of socks
- a laptop
- an iPad
- a passport
- toothbrush
- toiletries
- a water bottle
That gave us the basics for approximately 4–5 days of travel, although naturally your own packing needs will depend on the destination, season and type of clothing you take.
Light summer clothing, for example, will require considerably less space than heavy jumpers and winter trousers.
What fits in the main compartment?
The main compartment is where the majority of the available space is used.
For our test, four T-shirts and four pairs of trousers fitted into the main clothing area.
However, how you fold those items matters.
If you simply throw clothes into the backpack, pockets of unused space develop between them. Instead, folding items into similar rectangular shapes — or rolling suitable clothing — helps you use the width and depth of the compartment more efficiently.
The compression straps then help hold the clothing in position.
As a result, when the backpack is opened, everything remains considerably more organised than it would in a traditional top-loading rucksack.
Use different compartments for different jobs
Packing efficiently is not simply about putting as much as possible into the largest compartment.
In fact, one of the easiest ways to make a compact backpack feel bigger is to stop using the main compartment for everything.
The LEVARE backpack has separate areas for different categories of travel essentials.
Clothing
Keep your largest clothing items together in the main compartment.
For our test:
4 T-shirts + 4 pairs of trousers
formed the core of the packing setup.
Pyjamas and smaller clothing
The separate lower compartment can also be used for footwear, but during our own test we found it particularly useful for pyjamas and smaller clothing items when the main area was already full.
That gave us another place for:
- 2 sets of pyjamas
- underwear
- socks
without disturbing the main clothing compartment.
Laptop and tablet
Keeping technology away from clothing makes packing and airport access easier.
The dedicated laptop and organiser area gives you somewhere separate for items such as:
- laptop
- tablet
- charger
- cables
- smaller technology accessories
Instead of having to remove half of your clothes to reach your computer, you can keep your technology in its own section.
Toiletries
There is also a separate toiletries area.
This is useful because toiletries are usually the items you least want buried amongst your clean clothing.
For UK airport travel, remember that rules for carrying liquids can vary by airport. At many UK airports, liquids in hand luggage still need to be in containers holding no more than 100 ml, although some airports now operate different limits. The Government recommends checking the rules for every airport you will travel through.
Where should your passport and valuables go?
Not everything should be packed deep inside the bag.
Items such as your:
- passport
- wallet
- boarding information
- keys
- travel documents
are better kept somewhere secure but still accessible.
The hidden rear security pocket on the LEVARE backpack is designed for exactly this type of item.
Consequently, you do not need to open the main compartment every time you need your passport or another small valuable.
That is particularly useful while moving through airports and stations.
What about a water bottle?
A reusable bottle can take up a surprising amount of valuable internal space.
Therefore, using an external bottle pocket makes sense.
The LEVARE backpack has a dedicated side bottle pocket, which means the bottle does not have to compete with clothing or technology for internal storage.
Of course, remember that drinks count as liquids when passing through airport security, and the restrictions depend on the airport you are travelling through.
How much can you realistically pack for 4–5 days?
For many travellers, 4–5 days is realistic, particularly if you are travelling somewhere where lightweight clothing is appropriate.
A sensible example might look like:
Clothing
- 4 T-shirts
- 4 trousers or a mixture of trousers and lighter bottoms
- 2 pyjama sets
- 5 underwear
- 5 pairs of socks
Technology
- laptop
- tablet
- chargers
Travel essentials
- passport
- wallet
- phone
- documents
Toiletries
- toothbrush
- toothpaste
- personal care items
Other
- reusable water bottle
However, there is an important difference between what can physically fit and what you should pack.
If you continue adding items until every compartment is completely compressed, travelling with the backpack will become less convenient.
Instead, try to leave a little flexibility.
That makes it easier to:
- access items during the journey
- repack your bag at the hotel
- accommodate something purchased while travelling
- avoid excessive pressure on zips and compartments
An example of the clothing, technology and essentials we tested inside the LEVARE backpack.
How to get more from a 40 × 30 × 20 cm backpack
A few simple packing choices make a significant difference.
1. Pack outfits, not individual items
Instead of packing six tops because you might wear them, decide what you are likely to wear each day.
This immediately removes unnecessary “just in case” clothing.
2. Use the full shape of the compartment
Rectangular clothing stacks usually make better use of a rectangular backpack.
Therefore, fold or roll items so that they fill the edges rather than creating large gaps.
3. Put small items into otherwise unused spaces
Socks and underwear are particularly useful for filling smaller gaps between larger items.
4. Keep categories separate
Clothing should stay with clothing, technology in its dedicated section and toiletries together.
This does not technically increase the size of the backpack, but it makes the available space much easier to use.
5. Wear your bulkiest clothing
If you are travelling with a large jacket, heavy jumper or bulky shoes, wearing them during the journey can free up a substantial amount of bag space.
6. Avoid packing for unlikely situations
The phrase “I might need this” is responsible for a lot of overpacked luggage.
If an item is inexpensive and easily available at your destination, consider whether carrying it for the entire journey is really necessary.
Is 40 × 30 × 20 cm suitable for under-seat travel?
It can be, but this needs a careful answer.
Different airlines use different limits, and some fares include different baggage allowances.
For example, easyJet's current standard small cabin allowance is 45 × 36 × 20 cm, and the bag must fit underneath the seat in front of you.
The dimensions of the LEVARE Travel Backpack when fully packed are approximately 40 × 30 × 20 cm.
Nevertheless, you should always check the latest baggage policy for your airline before travelling because allowances can change.
This is also why we avoid describing the backpack as universally “airline approved”. There is no single cabin-bag standard covering every airline.
Is a 40 × 30 × 20 cm backpack better than a suitcase?
It depends on the trip.
A suitcase may make more sense if you need:
- formal clothing
- several pairs of shoes
- heavy winter clothing
- equipment
- significantly more than five days of clothing
On the other hand, a compact backpack can be particularly useful for:
- city breaks
- weekend travel
- business trips
- short European trips
- travellers who prefer to move without pulling a suitcase
- journeys involving trains and public transport
A backpack also leaves both hands free, which can make moving through stations and airports easier.
We will cover this in more detail in our upcoming guide:
Backpack vs Cabin Suitcase: Which Is Better for a Short Trip?
That article should internally link back to this one once published.
So, what does a 40 × 30 × 20 cm backpack actually fit?
More than the dimensions initially suggest.
In our own test, we were able to use the LEVARE Travel Backpack for a realistic 4–5 day packing setup, including clothing, pyjamas, underwear, socks, a laptop, tablet, toiletries, passport and water bottle.
However, the biggest advantage was not simply the amount that fitted.
It was where everything fitted.
By separating clothing, technology, toiletries, valuables and smaller essentials, you can use the available space more efficiently while still being able to find what you need.
Ultimately, the best compact travel backpack is not necessarily the one that allows you to force in the greatest number of items.
It is the one that lets you carry what you actually need without making the journey harder.
Explore the LEVARE Travel Backpack
Frequently asked questions
Can you really travel for five days with a 40 × 30 × 20 cm backpack?
Yes, it can be possible for light to moderate packers. We have tested the LEVARE backpack with clothing and essentials for around 4–5 days. However, bulky winter clothing or several pairs of shoes will reduce the amount you can fit.
Will a 40 × 30 × 20 cm backpack fit under an airline seat?
It fits within some airlines' current small-cabin dimensions, but there is no universal airline limit. Always check the airline's current baggage policy before travelling. The UK Government also advises passengers to check baggage size and quantity directly with their airline.
Is rolling clothes better than folding them?
Both can work. Rolling can be useful for smaller or softer garments, whereas neatly folded rectangular clothing can make very good use of a rectangular clamshell backpack. The best method depends on what you are packing.
Can I carry toiletries in the backpack?
Yes. The backpack has a dedicated toiletries section. If flying, however, make sure your toiletries meet the security requirements of the airports you will travel through.