10L, 15L, 20L… how to choose your backpack?
In summary:
- The capacity of a city backpack is measured in liters (L) and corresponds to the internal volume.
- 10L for minimalist use; 15L the most versatile for daily use; 20L for heavier use.
- A bag that is too small is restrictive, a bag that is too big is cumbersome and encourages overfilling.
- The perfect capacity depends on lifestyle, the quantity actually transported, and the need for flexibility.
- For most active city dwellers, a 15L city backpack is the sweet spot of comfort, style and functionality.
Choosing an urban backpack seems simple. Yet, this is often where the entire user experience hinges. Too small, and you'll be constantly making compromises. Too big, and it becomes cumbersome, unbalanced, and ends up carrying… nothing. Capacity, expressed in liters, is therefore much more than a technical figure: it's an indicator of how you experience the city, how you get around, work, shop, and even how you organize your thoughts. Here are a few tips to help you choose the right one.
10 liters, 15 liters, 20 liters… These numbers keep coming up, but what do they really mean? And above all: what is the ideal capacity for an urban backpack?
This article offers a clear, concrete and pragmatic reading to understand what these volumes represent, what they allow (or do not allow), and how to choose the one that really corresponds to your daily life, especially if you are looking for a versatile, elegant, comfortable and discreet bag for urban use.
Understanding the concept of capacity (in liters)
A backpack's capacity is expressed in liters (L), which corresponds to the total available internal volume. In practice, this includes:
- the main compartment,
- the internal pockets,
- sometimes the external pockets.
One liter corresponds to a cube of 10 × 10 × 10 cm. In other words:
- 10 L ≈ 10 one-liter cartons of milk,
- 15 L ≈ a small, well-filled office box,
- 20 L ≈ a very compact cabin bag.
But this equivalence remains abstract. What really matters is: what you can put inside without forcing it , without deforming the bag, without making it uncomfortable to carry.
10 liters: strict minimalism
A 10L urban backpack is very compact. It reflects a deliberately minimalist approach.
What you can put in it
Typically:
- a tablet or a very thin computer (13" maximum),
- a notebook or a small binder,
- a wallet, a phone, keys,
- a thin water bottle or a small bottle.
Benefits
- Very light, very discreet.
- Perfect for short trips, appointments, urban walks.
- Excellent aesthetically: slim silhouette, never bulky.
Boundaries
- Very intolerant of unforeseen events (rain, shopping, having to take off a jacket).
- It's impossible to put a sweater, lunch, or groceries in there.
- Not very versatile: it requires an extremely minimalist lifestyle.
👉 Conclusion: the 10L is suitable for strict urban minimalists, but it is often too restrictive for varied daily use.
15 liters: the urban balance
15 liters is often considered the "middle ground" capacity. This is no coincidence: it's the size that allows you to cover the majority of urban uses without becoming bulky .
What you can put in it
In practical terms, a 15L container allows you to carry:
- a laptop up to 14–15”,
- a notebook, a book or an A4 folder,
- a water bottle,
- a light sweater or a thin jacket,
- breakfast or takeaway lunch,
- a few emergency purchases.
Benefits
- Spacious enough for real life (and its unexpected events).
- It remains compact and elegant.
- Good balance between wearing comfort, weight and capacity.
- Very versatile: work, leisure, daily commutes, light weekends.
Boundaries
- Not suitable for transporting large volumes (large shopping bags, bulky photo equipment, shoes, etc.).
- Not suitable for heavy “technical” uses (sports, long journeys, hiking).
👉 Conclusion: 15L is the most versatile capacity for modern urban life.
20 liters: logistical comfort
20 litres marks a turning point: we leave the purely “urban” to move towards the urban-travel-sport hybrid.
What you can put in it
- computer + tablet + accessories
- change of clothes,
- lightweight shoes,
- complete meal
- book, headphones, chargers, etc.
Benefits
- Very comfortable in terms of capacity.
- Allows you to go away for a light weekend.
- Ideal for busy users (photographers, nomadic consultants, urban athletes).
Boundaries
- Larger on the back.
- More visible, less discreet.
- May encourage unnecessary overloading.
👉 Conclusion: the 20L is useful if you carry a lot of things, but may be excessive for typical daily urban use.
How to choose according to your lifestyle
Good capacity depends less on your body type than on your daily organization .
You are more of a…
1. Classic urban worker
Laptop, notebook, lunch, jacket → 15 L
2. Strictly minimalist
Tablet, wallet, keys → 10 L
3. Versatile Nomad
Work + sport + sometimes nights out → 20 L
Why “too big” is often a problem
It's often thought that it's better to "plan for a large quantity". In reality:
- An oversized bag becomes heavy even when empty.
- It changes your posture.
- It encourages you to carry more than necessary.
- It loses elegance and visual legibility.
Conversely, a slightly restrictive bag promotes:
- better organization
- more conscious consumption,
- a lighter silhouette.
The special case of the 15-liter model: why it works so well
The success of the 15L is not arbitrary. It corresponds very precisely to:
- the average size of modern laptops,
- the average size of a takeaway lunch,
- the amount of items that an urban adult actually carries.
It allows you to avoid making painful choices while also avoiding overload.
This is the capacity of “real life”, not that of the exception.
Capacity and aesthetics: an often overlooked point
A bag is part of your silhouette. Too big, it overwhelms you. Too small, it can seem inadequate.
The 15L generally respects the proportions of the adult bust, in both men and women, which contributes to an impression of visual balance.
In summary
|
Ability |
For whom |
Advantage |
Limit |
|---|---|---|---|
|
10 L |
Minimalists |
Discreet, lightweight |
Too restrictive |
|
15 L |
Multipurpose urban spaces |
Perfect balance |
Not for heavy loads |
|
20 L |
Loaded nomads |
Very comfortable |
Bulky |
Conclusion
The ideal capacity for an urban backpack isn't one that allows you to carry everything, but one that corresponds to what you actually carry. This should be achieved without restricting your movement, without weighing you down, and without throwing you off balance.
For the majority of active city dwellers, 15 litres is today the best compromise and the optimal balance point between freedom, comfort, aesthetics and frugality.
It is the capacity that accompanies modern life as it is lived: mobile, flexible, sometimes unpredictable but rarely extreme.
If you're looking for a backpack to navigate your urban life with ease, style, and simplicity, this is probably where you'll find the perfect fit. Furthermore, the accessories or equipment you want to carry, such as a laptop, water bottle, or umbrella, can influence the size of your bag, ensuring it meets all your daily urban needs.