Choosing the right backpack size for your adventures isn’t always easy (we get lots of size questions), especially when comparing our 18L, 28L, and 30L waterproof backpacks. While the 18L and 30L share a very similar streamlined design, the 28L has a noticeably different shape and layout, making each pack suited to different types of trips and everyday use.
To help you find the right fit, we’ve put together a side-by-side backpack size comparison, along with a few practical tips and insights to make choosing your next DryTide pack a little easier.
18L → everyday commuting, cycling, smaller people
28L Point Nemo → maximum waterproof protection, boating, kayaking, photographers
30L → best all-round backpack for travel and day trips
50L → multi-day travel and bigger adventures
LENGTH: 29cm (11 1/2″)
WIDTH: 13cm (5″)
HEIGHT (backpack closed): 48cm (19″)
HEIGHT (roll down extended): 63cm (24 4/5″)
LENGTH: 30cm (11.8″)
WIDTH: 20cm (7.8″)
HEIGHT: 48cm (18.9″)
This is not a roll down backpack so height is fixed.
LENGTH: 32cm  (12 1/2″)
WIDTH: 17cm (6 3/4″)
HEIGHT (backpack closed): 55cm (21 1/2″)
HEIGHT (roll down extended): 68cm (26″ 2/3)
*All measurements were taken with the backpacks lying flat on a level surface.
We calculated the volume of each backpack based on its dimensions. This method proved quite accurate for the more box-shaped 18L and 30L backpacks. For the Poin Nemo, because of its rounded shape, calculating volume from external dimensions slightly overestimates the usable capacity. To get a more realistic measurement, we also tested the true carrying capacity of each backpack by filling them with water.
Here are the results:
The measured volume of the 18L backpack is approximately
20–22L
depending on how tightly you roll down the top closure. Leaving the roll-top fully extended adds even more space, increasing the total capacity by an additional 3–4L when needed (backpack stays opened).
The measured volume of the 28L Point Nemo backpack is approximately
24L
Unlike our roll-top backpacks, the Point Nemo features a fixed-shape design, so its capacity cannot be expanded or adjusted. Its more rounded profile also means the real-world measured volume comes out slightly lower than the calculated volume based on dimensions alone.
The measured volume of the 30L daypack is approximately
29–31L
depending on how tightly you roll down the top closure. Leaving the roll-top fully extended adds even more space, increasing the total capacity by an additional 4–5L when needed (backpack stays opened).
In practice, the 18L feels slightly larger than its name suggests, the 30L delivers almost exactly its advertised capacity, while the Point Nemo trades a little usable volume for its fully airtight construction and zipper closure.
Here you can see all three backpacks photographed side by side. The difference in external size is surprisingly small, especially between the 18L and 30L backpacks, which share the same roll-top design. The real difference becomes noticeable once you start packing. The 30L comfortably carries bulkier gear, such as an extra sweater, towel or additional layers, making it a better choice for longer day trips and travel.
For everyday use or users with a smaller frame, the 18L Waterproof Backpack or the Point Nemo Airtight Backpack are often the more natural fit. Although Point Nemo has a nominal capacity of 28 litres, its rounded shape and airtight zipper result in a usable packing space that feels closer to the 18L (but still bigger). In return, you get faster access to your gear, the highest level of waterproof protection in the DryTide range, and a more rounded silhouette that resembles a traditional backpack rather than a typical roll-top waterproof backpack.
Here are examples of people wearing backpacks for real life backpack size comparison. The male model is 182 cm tall (6 ft), and the female model is 174 cm tall (5ft 9″).
While the three backpacks are similar in overall size, they are designed for different types of adventures.
Choose the 18L Waterproof Backpack if you want the lightest and most compact option for everyday carry, commuting and short outdoor trips.
Choose the 30L Waterproof Backpack if you’re looking for the most versatile all-round backpack. It’s the best choice for travel, hiking, surf trips, beach days and everyday adventures where you need a little more space.
Choose the 28L Point Nemo Airtight Backpack if you prefer the convenience of a waterproof zipper over a roll top, frequently use your backpack on boats or kayaks, or simply want the highest level of waterproof protection we offer.
No matter which backpack you choose, all three are carry-on compatible, fully waterproof and built to protect your gear during adventures around water. The right choice ultimately comes down to how much you carry and the type of adventures you enjoy most.
Still unsure? Contact us.
Is 18L enough for everyday use?
Yes. The 18L Waterproof Backpack is designed specifically for everyday carry. It easily fits daily essentials like a laptop, charger, water bottle, lunch, an extra layer and other personal items. If you mainly use your backpack for commuting, work, school or short outdoor trips, 18 litres is enough for most people while keeping the backpack compact and lightweight.
Is 30L too big for everyday use?
Not at all. While the 30L Waterproof Backpack offers noticeably more space than the 18L, its slim design makes it comfortable for everyday use. Many customers choose it because the extra capacity is useful for the gym, groceries, travel or carrying additional clothing, without feeling oversized during daily commutes.
Why does Point Nemo hold less than 28 litres?
Point Nemo’s airtight waterproof zipper and rounded construction create a different internal shape than a traditional roll-top backpack. While its nominal capacity is 28 litres, the usable packing space is closer to 24 litres. This is because the airtight zipper and rounded design prioritise maximum waterproof protection over expandable storage. In return, you get superior waterproof protection, faster access to your gear than with a roll-top closure, and a rounded silhouette that looks and feels more like a traditional backpack than a typical waterproof roll-top backpack.
While Point Nemo is officially rated at 28 litres, its practical packing capacity is closer to 24 litres due to its airtight zipper and rounded construction. Future production batches will reflect this measured capacity more accurately.
Which backpack fits a 16-inch laptop?
All three backpacks can fit most 16-inch laptops. For the best protection, we recommend using the optional DryTide Laptop Sleeve (either padded or waterproof version), which attaches securely inside the backpack using the integrated Velcro mounting system. This keeps your laptop protected while preventing it from moving around inside the main compartment.
Which backpack is best for airline carry-on?
The 18L Waterproof Backpack, 30L Waterproof Backpack and 28L Point Nemo Airtight Backpack are all suitable for carry-on travel with most airlines. Because they have a flexible construction without a rigid frame, their overall size also depends on how fully they are packed. Unlike a hard-shell suitcase, they can compress slightly when not filled to capacity. If you frequently travel by air, the 30L is the most versatile choice, although when packed completely full it may exceed the carry-on size limits of some airlines. The 18L is the safest option if you prefer travelling light or regularly fly with stricter baggage allowances.
Which backpack is best for hiking?
It depends on the type of hiking you do. The 30L Waterproof Backpack is the best all-round choice for most hikes thanks to its versatile capacity and roll-top design. If your adventures regularly involve river crossings, waterfalls, heavy rain or wet conditions, the 28L Point Nemo Airtight Backpack offers the highest level of waterproof protection. For shorter day hikes and everyday outdoor use, the 18L Waterproof Backpack is a lightweight and compact option.
Does the 30L Backpack Look Much Bigger Than Point Nemo?
Not really. Although the 30L Waterproof Backpack offers noticeably more usable storage space, the overall external dimensions of the two backpacks are surprisingly similar. The main difference comes from their design. The 30L uses a roll-top closure that provides more flexible packing capacity, while Point Nemo uses an airtight waterproof zipper and a rounded shape that gives it a more traditional backpack appearance. If you need more packing space for clothing or bulkier gear, the 30L is the better choice. If maximum waterproof protection is your priority, Point Nemo is the better option.
Does the 30L Backpack Hold Much More Than Point Nemo?
Yes. Although the two backpacks have similar external dimensions, the 30L offers noticeably more usable packing space. Its roll-top closure allows the main compartment to expand, while Point Nemo’s airtight zipper and rounded construction prioritise waterproof performance and quick access over maximum storage volume.
Still unsure? Contact us.
