A dry bag is useful when you want a simple extra layer between clothing or gear and splashes, sand, damp ground or changing outdoor conditions. One of the biggest questions when choosing one is size: should you carry a 5L, 10L, 15L or 20L bag?
There is no single best size for every trip. The right capacity depends on what you want to keep together, how much space you have in your pack or vehicle, and whether the dry bag is being used for a few small essentials or a larger group of soft goods.
What does dry bag capacity mean?
Dry bag sizes are usually listed in liters. A larger liter number generally means more internal storage space, but the usable space can vary depending on the shape of the bag and how securely the roll-top closure needs to be folded.
Do not plan to fill a roll-top bag all the way to the opening. Leave enough room to close it according to the product instructions.
When a 5L dry bag makes sense
A 5L bag is a compact option for smaller items. Depending on the dimensions of your gear, it can be useful for grouping things such as a lightweight layer, small towel, accessories or other personal items that you want separated from the rest of your pack.
Its main advantage is packability. A smaller bag is easier to fit inside a daypack, tote or larger camping bag without taking over the entire storage area.
When to consider a 10L dry bag
A 10L dry bag provides more room while remaining relatively compact. It can work well when you want to keep several soft items together, such as an extra shirt, socks, trail towel and a few campsite accessories.
For day trips, beach use, paddling or general camping organization, this middle size can be a practical balance between capacity and packed bulk.
15L and 20L dry bags for larger loads
A 15L or 20L dry bag gives you more flexibility for bulkier clothing, multiple layers or a larger collection of soft gear. These sizes can be useful for car camping, longer day trips or situations where you want one larger bag instead of several small ones.
The trade-off is that a larger bag takes up more room when full. Before choosing the biggest size automatically, consider where the bag will sit inside your backpack, vehicle or campsite storage setup.
Roll-top closure matters
The roll-top is an important part of how this style of bag helps protect its contents. Keep the opening free of bulky objects that interfere with the closure, follow the manufacturer's closing instructions and secure the buckle before use.
A roll-top outdoor dry bag should not automatically be treated as a certified submersible case. If an item cannot tolerate water exposure at all—such as certain electronics, documents or medications—use protection appropriate for that item's risk and the activity.
Dry bags are also useful for organization
Even when heavy water exposure is not expected, dry bags can help separate clean clothing from damp equipment, keep small gear grouped together or create simple categories inside a larger backpack.
Using different sizes can make packing easier. For example, a smaller bag can hold frequently accessed items while a larger one carries spare clothing or other soft gear.
What size should you choose?
- 5L: compact storage for a small group of essentials.
- 10L: useful middle size for day trips and several soft items.
- 15L: more room for clothing and larger gear groups.
- 20L: a larger option for campsite, travel or vehicle-based storage.
These are general packing examples rather than fixed item counts. The dimensions and shape of your actual gear determine what will fit.
Build the rest of your wet-weather setup
A dry bag protects gear differently from outer rain protection. Hikers may also use a backpack rain cover to help keep precipitation off the outside of the pack. Using more than one layer of protection can be useful when conditions are wet.
The Mountain Barracks Roll-Top Outdoor Dry Bag is available in 5L, 10L, 15L and 20L options and is designed for protective outdoor storage around camping, travel, paddling and beach use.
You can also browse Featured Gear for more practical campsite and trail equipment.
Bottom line
Choose a dry bag based on what you actually plan to carry, not simply the largest capacity available. Leaving enough room for the roll-top closure and matching the bag to your pack can make a simple piece of outdoor storage much more useful.
Related guides: Backpack Rain Cover Guide, 50L vs 60L vs 80L Hiking Backpack Guide and Lightweight Rain Jacket Guide.