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Everyday Carry
Every bag spec sheet lists a number followed by the letter “L.” A 20L backpack. A 30L duffel. A 40L weekender. The problem is that liters, as a unit of measurement, mean almost nothing to most people outside of buying soda or filling a gas tank.
So when a product page says “20-liter capacity,” what does that actually look like when you are packing for work, the gym, or a weekend trip? This guide breaks down common bag capacities into real-world terms, maps them to specific use cases, and helps you figure out which size you actually need before you end up with a bag that is too small to be useful or too big to carry comfortably.
What “Liters” Means on a Bag (and Why It Is Not the Whole Story)
A liter is a unit of volume. One liter equals roughly 61 cubic inches. When a bag is listed at 20L, the manufacturer is saying the interior holds about 20 liters of stuff, or roughly 1,220 cubic inches.
That sounds straightforward, but there are two catches. First, there is no universal standard for how brands measure internal volume, and some manufacturers measure total volume, including every pocket and sub-compartment. Others measure only the main compartment. With both of those in mind, two bags both listed at 20L can feel noticeably different in usable space depending on how the measurement was taken and how the interior is structured.
The second is that the shape matters as much as volume. A tall, narrow 20L backpack and a wide, shallow 20L tote hold the same theoretical volume, but they pack very differently. The backpack swallows a laptop and a few slim items stacked vertically. The tote spreads items flat and gives you easy top-down access. Same liters, different experience.
The takeaway: treat the liter count as a useful starting point, not an exact science. The packing examples below will give you a more practical sense of what each capacity range actually holds.
5L: The Essentials-Only Tier
At five liters, you are carrying the bare minimum. Think of this as the size of a large toiletry kit or tech pouch. There is room for a few small items and nothing else.
What fits: a toothbrush, toothpaste, razor, deodorant, a small bottle of shampoo, and a couple of other grooming items. Or, in a tech-oriented layout: a laptop charger, a power bank, a few cables, earbuds, and a pen or two.
Who needs this size: anyone who wants a dedicated organizer that lives inside a larger bag. The NORWALK+ Toiletry Case at 5L and the NORWALK Tech Case at 3L both fall into this category.
Best for: toiletry organization, tech accessory storage, small item consolidation inside a larger bag.
9L: The Dopp Kit
Nine liters gives you a proper toiletry bag with room to spare. You can pack full-size bottles, a hanging strap for hotel bathrooms, and still have space for extras like a first aid kit or medications.
What fits: full-size shampoo and conditioner bottles, a razor and shaving cream, toothbrush and toothpaste, deodorant, sunscreen, a comb, contact lens supplies, and a few extras in zippered side pockets.
Best for: travel toiletries, weekend trip grooming kits, keeping all bathroom items in one grab-and-go package.
16L: Daily Carry Without a Laptop Backpack
Sixteen liters is the sweet spot for a daily tote or lightweight carry bag. It is big enough to hold a laptop, a few personal items, and a water bottle, but compact enough that it does not feel like luggage.
What fits: a 16-inch laptop in a padded sleeve, a notebook or planner, a phone charger, a water bottle (up to 40 oz if the bag has a dedicated pocket), a light jacket or sweater, a small lunch container, and a wallet and keys.
What does not fit comfortably: a full change of clothes, bulky gym shoes, or multiple days’ worth of gear.
Best for: daily commute (office or hybrid work), errands, short meetings, light day trips.
18L: The Messenger Sweet Spot
Eighteen liters in a messenger or crossbody format gives you a different packing profile than a backpack of the same volume. Messenger bags tend to be wider and shallower, which means better access to documents and flat items but less depth for bulky gear.
What fits: a 17-inch laptop and tablet in padded sleeves, a folder or stack of documents, a notebook, charger and cables, a book or two for the commute, a water bottle (in an external pocket), and quick-access items like a passport, phone, or wallet in rear pockets.
Best for: office commute, business travel day bag, client meetings, public transit carry.
20L: The Everyday Backpack
Twenty liters is the most popular capacity for daily-use backpacks, and for good reason. It holds everything most people carry on a normal day with a small margin for extras, without crossing into “hiking pack” territory.
What fits: a 17-inch laptop and tablet, a phone charger and power bank, a water bottle (up to 40 oz in a side pocket), a light jacket, a lunch container, headphones, a notebook, sunglasses in a padded pocket, keys, and a wallet. If you pack efficiently, you can also squeeze in a thin sweater or a small umbrella.
What pushes the limits: a full set of gym clothes and shoes on top of your work gear. At 20L, adding gym stuff means you are packing tight and probably leaving something behind.
The NORWALK 20L Backpack and NORWALK+ 20L Backpack both sit at this capacity. The difference between the two comes down to base construction (tarpaulin vs. thermoformed) and hardware details, but the volume and core layout are the same. Both feature magnetic side pockets that hold up to 40 oz bottles, RFID-blocking front pockets, and a separate padded laptop compartment.
For a deeper look at what makes a backpack hold up over years of daily use at this capacity, Veto’s guide to the anatomy of a great backpack breaks down the features that matter.
Best for: daily commute with laptop, school or grad school carry, light travel day bag, everyday carry.
30L: Gym Bag Territory
Thirty liters is where you cross from “daily carry” into “activity bag.” This is the capacity that comfortably holds a full gym kit alongside your regular items, or serves as a generous day bag for hikes and outdoor trips.
What fits: a pair of gym shoes in a separate compartment, workout clothes (shorts, shirt, socks, underwear), a towel, a full-size water bottle, toiletries or a change of clothes for after the gym, plus your phone, wallet, and keys. If you are using it for a day trip instead, 30L holds layers, snacks, a first aid kit, a rain shell, and a water bladder or bottles.
Best for: gym sessions, day hikes, overnight at a friend’s place, sport-specific gear hauling.
40L: The Weekender and Travel Tier
Forty liters is the point where a bag becomes genuine luggage. This is enough volume for a multi-day trip without checking a bag, and it is the upper end of what most airlines allow as a carry-on duffel.
What fits: four to five days’ worth of clothes (rolled, not folded), a pair of shoes in a separate compartment, toiletries in a dedicated pouch, a light jacket, a book or tablet, chargers and tech accessories, and still enough room for souvenirs on the way home. For a weekend trip where you are packing less carefully, 40L swallows jeans, a couple of shirts, underwear, a hoodie, and everything else without a fight.
Best for: weekend trips, 3-to-5-day vacations, carry-on travel, road trips, work trips that require more than a backpack.
How to Pick: Match the Capacity to Your Actual Day
The most common mistake is buying a bag based on the biggest trip you might take instead of the trip you take most often. A 40L duffel is fantastic for a long weekend, but if you use it as a daily commuter bag, you will be hauling an oversized, half-empty sack every day.
Start with your most frequent use case. If you commute to an office five days a week and travel once a month, your primary bag should be a 16L to 20L. The travel duffel is a separate purchase for a separate purpose.
Here is a quick reference:
- Running errands, light daily carry: 16L (tote or small backpack).
- Office commute with laptop and essentials: 18L to 20L (backpack or messenger).
- Commute plus gym, or a heavier daily loadout: 30L (duffel or large backpack).
- Weekend trips, multi-day travel, carry-on luggage: 40L (travel duffel).
- Toiletries and tech accessories: 3L to 9L (organizer pouches that nest inside your main bag).
And if you want to understand the construction details that separate bags built to last from bags built to a price point, our buyer’s guide to bag quality walks through stitching, zippers, hardware, and base construction in detail.
