Several participants in my upcoming Intro to Backpacking event have asked me to suggest a minimum size backpack for backpacking.   The answer isn’t as straight forward as it may seem, so I’m going to talk about several different pack sizes that work for me for different tripsthroughout the year.  It is important to note that I usually carry minimalist style gear. I also know that I’m prone to over-pack if my pack is too large, so I always go for the smallest possible backpack. 

The Minimum Size Backpack for Backpacking Varies

Everything I’m about to discuss applies to normal conditions in the North Eastern United States below treeline.  If you’re out west and you need to carry extra water, you may need a heavier duty pack. If you’re climbing mountains in winter, you definitely need a heavier pack.  As with all backpacking gear, you must select a pack that is suitable for the conditions you’re going to use it in. Does your pack have to carry a lot of water? Ice climbing tools? Pack rafting gear? A mountaineering tent?  The guidelines below assume that the answers to these questions are No.

Minimum Size Backpack for Summer in the Northeast

For example, if you’re only doing 1 or 2 night trips in the summer in the north-east, you could probably use a 36 liter pack if you had a small enough tent and sleeping bag. For this, I would recommend something like the Gossamer Gear Kumo.  It’s a simple pack that only weighs 18 ounces empty. It has nice features like reachable water bottle pockets, an external mesh pouch for gear you want during the day, and even shoulder strap pockets for your phone and camera.  This is a very basic frameless pack that uses a sit pad or a sleeping pad for support. That said, 36 liters is really small.  There won’t be any extra room to add extra clothing for colder weather or extra food for longer trips.  It’s really just a simple weekend pack for experienced backpackers in nice weather.

Minimum Size Backpack for Longer Three Season Trips

I use a 40 liter Gossamer Gear Gorilla for most hikes from 1-4 nights in spring, summer, and fall. This is a more rugged pack that weighs 30 ounces fully configured, but it has components you can remove to save weight. Whereas the Kumo has no built-in frame and relies only on a pad, the Gorilla has a removable wire frame.  The frame is nice when you’re carrying a heavier load or can help give it form when the pack is mostly empty. I almost never use it. Removing it saves about 3 ounces.  The Gorilla also has a beefier belt that does a great job transferring load to your hips.  When ever you’re carrying more than 20 pounds, its good practice for most of the weight to be on your hips and not your shoulders.  Other than that, the Gorilla is very similar to the Kumo.  It has great water bottle pockets, an even larger mesh pocket, and a simple closure system.

Minimum Size Backpack for Winter and Long Trips

For me, 40 liters isn’t enough in the winter or for week-long trips in the summer. Winter clothing and sleeping bags tend to take up more space.  Likewise, I can only carry about 4 days worth of food in my Gorilla.  I use a Gossamer Gear 60 liter Gear Maripossa when I need extra space.  The Maripossa is basically the same design as the Gorilla (in fact, the belts are interchangeable) but it’s bigger. The one big difference is that the Maripossa has an extra deep side pocket on one side and an extra top pocket on the other.  The deep side pocket comes in handy if you’re carrying bush-craft tools like a knife or saw or liquid fuel bottles. Some people use this pocket for their tent so that they don’t need to open their pack to use it.  I put my rain gear in the top pocket on the other side, but its small and doesn’t have a lot of great uses.

Backpack Volumes Explained

There’s a bit of something you need to understand about pack volumes.  Gossamer Gear and most cottage manufacturers measure capacity up to the bottom of the extension collar. The extension collar is the part of the pack that folds or rolls up for closure. Almost all of this style pack has extra room available in the collar.  When you count this extra space, the Kumo is really about 40 liters, the Gorilla is 46, and the Maripossa is 70.  Just keep this in mind when comparing these packs with other brands.

Finding the Sweet Spot

The following chart is meant to summarize my recommendations for backpacking volume.  When picking your first pack, look for something large enough to cover most of the trips you’re likely to go on.  If you really get into backpacking, you are going to end up owning more than one pack.  I find that the sweet spot for a beginner is between 50 and 60 liters, but you could go as low as 45 with care.

Recommended Brands

You may have realized that I like Gossamer Gear packs.  I find that this brand strikes the right balance between cost, weight, and features.  Store bought brands like Osprey, REI, or Gregory are usually heavier and/or more expensive than Gossamer Gear. They have a lot of extra bells and whistles, but most of these aren’t needed.  If you’re looking at the name brands, try to keep it simple.  I like the Ospry Exos series and the REI Flash series.  You could also consider the Granite Gear Crown or Blaze.  All of these packs are made from durable materials have frames that can carry a heavier load than most ultralight packs; but they’re heavier.

On the other end of the spectrum are manufacturers like Zpacks and Hyper Light Mountain Gear.  These companies use an exotic material called Dyneema Composite Fabric to make their packs strong, waterproof, and ultralight.  If you have the money, its worth considering these companies. Zpacks weigh about the same as Gossamer Gear, but all of their packs have  hybrid external frames that help to carry heavier loads more comfortably.  HMG packs are spartan by comparison, featuring only design elements that are necessary.

Another serious contender in the cottage market is Ultralight Adventure Equipment (ULA).  ULA packs tend to be slightly heavier than Gossamer Gear packs, but they’re known to be more durable and can carry heavier loads. These are real favorites among thru-hikers on the Appalachian Trail.