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How to Choose an Ultralight Backpack

How to Choose an Ultralight Backpack
The Mariposa out for a few days hiking through the backcountry of Grand Teton National Park. The pack has ample room in the side pockets for stoves, bottles, and food, while the mesh pocket is large enough for a few extra layers.
Credit: Jane Jackson
Wednesday April 29, 2020

Once you've tasted the freedom of an ultralight set-up, it's hard to imagine going back to a four or five pound pack, no matter how supportive and high-tech the suspension system. With an ultralight kit, you can carry under 30 pounds for multiple days in the backcountry, allowing for more time to enjoy the wilderness and less time complaining about your aching knees. Needless to say, we are sold.

This review covers packs that are under two and a half pounds, with the lightest weighing just over a pound. This dramatic drop in weight from a normal pack means that things like storage and durability are sacrificed. Most of the packs in this review average around 38 liters for total carrying capacity. For reference, most of the packs we test in our Best Backpacking Backpack weigh in between four and six pounds, and have a main compartment volume of 60 liters or so. It's crucial to get your kit to weight under 30 pounds to make these lightweight packs worthwhile and comfortable.

None of the ultralight packs we tested will be incredibly comfortable with a 40 pound load, and it's unlikely that you'll be able to fit that much gear anyway. Head over to our Backpacking Backpack review for larger load carriers.

This review is one in a series of reviews that highlight gear used by lightweight and ultralight backpackers and thru-hikers. Head over to our Best Ultralight Sleeping Bag and Best Ultralight Tent reviews for the best of the best products to add to your ultralight kit. Each one of these reviews has a Buying Advice section that breaks down what we consider to be ultralight and lightweight loads for backpacking. There you will find detailed advice on selecting a tent shelter, sleeping bag, and sleeping pad that will slim down the overall weight of your kit — while still maintaining a reasonable margin of safety in the backcountry.

ultralight backpack - the two previous generations of the zpacks arc blast...our lead...
The two previous generations of the ZPacks Arc Blast...our lead tester is wearing our test model. Drawing on the experience of our extended group of testers and friends creates the world's best side-by-side gear reviews.
Credit: Brandon Lampley

Transitioning to an ultralight kit can be rocky. We highly recommend testing out your kit before hitting the trail to make sure things work well together. In general, we found that keeping your load between 15 and 30 pounds with these packs is the optimal place for comfort and enjoyment. This probably means slimming down other aspects of your Big Four beyond simply your pack (i.e., shelter, sleeping bag, sleeping pad). All of the information provided below is meant to help you with your decision-making process as you find your way to the ideal lightweight pack.

Types of Ultralight Backpacks

We will start by discussing the different types of ultralight packs: Simple Frame, Tensioned Air Frame, and Frameless.

Simple Frame

Simple frames come in a couple of varieties, and for this category, we define a simple frame as a frame that is not arc-ed and held in tension to create airspace at your back. Think of a simple foam panel with aluminum stays for additional support. At the simplest end of the frame spectrum is the throwback design of the Hyperlite Mountain Gear Windrider, with two independent flat aluminum stays placed vertically in the back panel. More advanced are the upside-down U shaped frames of the Editors' Choice Gossamer Gear Mariposa and the ULA Circuit, in tubular aluminum and carbon/Delrin, respectively.

Simple frames prevent torso collapse in the pack body, and help load transfer to the hip belt. The models we tested with simple frames are:
  • Gossamer Gear Mariposa
  • Gossamer Gear Gorilla
  • ULA Circuit
  • ULA Ohm 2.0
  • HLMG Windrider 3400
  • HLMG Porter 3400

ultralight backpack - out for a trip along the continental divide in rocky mountain...
Out for a trip along the Continental Divide in Rocky Mountain National Park with the HMG Windrider. We found the simple aluminum stays in this model inferior to more modern simple frames like that of the Gossamer Gear Gorilla, which more comfortably carries 25 or 30 pounds.
Credit: Brandon Lampley

Tensioned Air Frame

Several of the packs we tested incorporate a tensioned frame that is not only designed to carry loads well but creates space at your back for airflow. These packs are similar to the models you may find in our backpacking pack review, only simplified. Many hikers that tend to sweat a lot or whose adventures are primarily in warm to hot seasons of the year prefer a pack with ventilation between a potentially sweaty back and the backpack. The Osprey Exos 48 and Top Pick ZPacks Arc Blast 55 both use light tensioned frames.

In addition to usually carrying heavier loads more comfortably, a tensioned frame creates a ventilated airspace between your back and your pack's body. The models we tested with tensioned frames are:
  • Osprey Exos 48
  • Osprey Levity 45
  • ZPacks Arc Blast 55

ultralight backpack - surveying the divide from the mummy range in rmnp. we found the...
Surveying the Divide from the Mummy Range in RMNP. We found the tensioned air frame of the Osprey Exos 48 the best of this bunch for carrying 25 pounds or more. The Exos isn't the lightest pack we tested, but it includes all the bells and whistles.
Credit: Brandon Lampley


For very light loads, many enthusiasts carry a smaller pack than those we tested here. With overall loads less than 15 pounds, a frame becomes less important for carrying comfort. But in this review, we focused on packs capable of carrying loads up to 30 pounds when necessary. The only frameless pack we tested, the Granite Gear Virga 2, is a throwback to an era when many, if not most backpackers, carried a closed-cell foam sleeping pad. The Virga is designed to function best when a rolled closed-cell foam pad is placed inside, forming a barrel-like frame.

The Granite Gear Virga 2 is a large volume frameless pack that performs best when a rolled closed-cell foam pad is placed inside forming a "barrel frame."

Best Uses for Ultralight Backpacks

Seems fairly simple, right? You'll find these ultralight packs perfect for you if your backpacking adventures are focused more on covering the miles in unburdened comfort, and focused less on carrying lots of kit and luxuries for camping. In addition to the main compartment, lots of external storage provides quick access to food and important clothing layers while on the go.

ultralight backpack - headed up into colorado's indian peaks wilderness for a peaceful...
Headed up into Colorado's Indian Peaks Wilderness for a peaceful overnight and some sunrise fly fishing in the high alpine lakes. With a very light load, the frameless Granite Gear Virga 2 was a good choice.
Credit: Brandon Lampley

Ultralight Backpacking

To us here at OutdoorGearLab, ultralight backpacking is all about minimalism and efficiency; carrying just the right amount of the best gear to stay safe, warm, and happy while maximizing your trail time. Most experienced thru-hikers and ultralight enthusiasts have developed three-season backpacking kits with a base weight of 7 to 11 pounds. At the lighter end of this spectrum, many forgo a stove for cooking. At the heavier end are folks that cook some of their meals, carry a few extra warm clothing layers, and have a few luxury items like a camera or Kindle. Add in consumables, and pack weights are often in the high teens or low 20s. When our lead tester packed for a wintertime 250-mile chunk of the Appalachian Trail, his base weight came in at 13 pounds.

We strongly feel the four top-scoring packs we tested (all of which have minimal frames for support) are the best choice for most ultralight backpackers for three-season use. The best of these packs also provide the capacity and load-carrying ability to tackle cold, winter conditions. For folks with heavier base weights, we recommend the fully-featured Gossamer Gear Mariposa. If you're gearing up for winter travel, we recommend a pack from Hyperlite - we like the Porter best. On the other end of the spectrum, the ZPacks Arc Blast 55 is our go-to pack when total weight rarely gets above the teens.

Lightweight Backpacking

We define lightweight backpacking, and any backcountry travel with a base weight is between 13 and 20 pounds. The majority of novice backpackers seeking to reduce their loads to the lightest possible weight (without compromising their safety or spending a few thousand dollars on equipment) fall into this realm. It is quite common for relatively new folks gearing up for a thru-hike of a long trail to develop a kit that weighs in around 13 to 15 pounds. You can pull this off quite affordably. With a base weight in this range, you'll commonly carry 25 pounds once you add in consumables. An ultralight pack with a simple frame or tensioned frame for support is the perfect choice for you. The Gossamer Gear Gorilla, ULA Ohm 2.0, and Osprey Exos 48 handle these loads really well.

ultralight backpack - out on a dayhike with a light load in the rei flash. we went out for...
Out on a dayhike with a light load in the REI Flash. We went out for long day with both light and medium loads to evaluate each pack's carrying comfort and adaptability. Wandering around up at Chief Hosa, Colorado.
Credit: Brandon Lampley


Thru-hiking, or tackling one of the many popular long-distance trails like the Pacific Crest Trail or Appalachian Trail, is really no different than ultralight and lightweight backpacking described above. With the exception that the time spent carrying your house and home on your back is measured in months rather than days or weeks. While paring down your kit to the lightest safe weight for you is compelling, so is the ability to carry a substantial load when it is necessary. In sections of the Mojave desert in Southern California, PCT hikers need to carry six or more liters of water for a few days. On long trails, it is also not uncommon to carry a week's food or more while hiking through some of the more remote terrain. The Gossamer Gear Gorilla, ULA Ohm 2.0, Osprey Exos 48, and the Osprey Levity 45 are all excellent choices for thru-hikers because they can comfortably handle the heavier loads that are sometimes necessary. The ZPacks Arc Blast 55 is perfect for folks moving fast enough to avoid the heavier loads.

ultralight backpack - taking a stop to brew some coffee while whizzing through great smoky...
Taking a stop to brew some coffee while whizzing through Great Smoky Mountains National Park in winter. The Gossamer Gear Gorilla carried Brandon's mid 20s pound load very comfortably. The Gorilla earned our second highest overall score.
Credit: Brandon Lampley

Backpack as Part of a System: The Big Four

We talk a lot about the Big Four when it comes to selecting your backpacking kit. This includes your shelter, sleeping bag, sleeping pad, and pack. For most backpackers focused on hiking with very light loads, these are the four heaviest single items carried. You'll see that many other authors describe the Big Three. Here at OutdoorGearLab, we feel a good sleeping pad is as critical as the other three items for safety and comfort. Again, see our buying advice for tent shelters for the fine details of how the weight of these items adds up. To define some general weight ranges for lightweight and ultralight backpacking kits, the most important measurement is base weight. Base weight is defined as the total weight of the equipment commonly carried on your back, not including the weight of consumables like food, cooking fuel, and water.

Lightweight System

We define a lightweight backpacking kit as a base weight of 20 pounds or less. It is ubiquitous for thru-hikers, both new and experienced, to hit the big trails with a 13 to 15 pound base weight. An excellent goal for selecting the Big Four items is no more than eight pounds total. This is usually a much more budget-friendly goal as well.

ultralight backpack
Credit: OutdoorGearLab

Our recommendations for a 13 - 15 pound base weight, which means you'll often be carrying 25 pounds, and sometimes more, are the Gossamer Gear Gorilla, ULA Ohm 2.0, and Osprey Exos 48. We judged all of these packs' ability to comfortably carry 30 pound loads as "Great."

Ultralight System

We consider carrying a base weight of 12 pounds or less to be ultralight backpacking territory. Our lead tester carries a 13 pound base weight in winter that includes a few "heavy" luxury items. Most of our ultralight testers' three-season base weights are around 7 to 9 pounds. For the Big Four, 5 pounds total is an upper limit.

ultralight backpack
Credit: OutdoorGearLab

Our recommendations for folks building a 7 to 9 pound three-season base weight (which means you'll often carry 15 and rarely more than the low 20s) are the ZPacks Arc Blast 55 and the Gossamer Gear Mariposa or the Gossamer Gear Gorilla. The Arc Blast is the best ultralight backpack if you very rarely carry loads above the teens. The added eight ounces of the Gorilla is well worth it if you need to scale up your load carried. It handles loads in the mid-20s as well as any other we tested, and we feel it's much more adaptable for winter trips or carrying a week's worth of food and fuel.

The Big Questions

What Volume?

Two trends in the outdoor adventure world are contributing to both thru-hikers and backpackers carrying smaller backpacks than before. Compared to years past, we often carry less equipment, and what we do select is more technologically advanced, multipurpose, and much lighter. Years ago, it was not uncommon to carry a 65-liter pack with a 40 or 50-pound load for a week out in the backcountry. Nowadays, that is almost unheard of in serious ultralight backpacking circles. Most folks are leaning toward packs with a main compartment volume that hovers around 40 liters with up to 10 liters of additional storage on the outside of the pack.

Even still, many folks prefer a pack that errs on the side of larger rather than smaller. It's nice to have more room for big food loads when necessary and the ability to scale up your base weight for winter. Our lead tester usually rolls with a seven pound base weight but scales up to 13 pounds for winter. The Mariposa readily accepts this more significant load and carries it well. A pack like the Exos 48 with an additional 10 liters or so of storage is perfect for lightweight backpackers. It also carries a bit heavier loads better than others. We dialed in our selection for this review to mostly focus on models with an approximate 50-liter total volume.

ultralight backpack - we lugged a lot of chairs and odd shaped gear around while crewing...
We lugged a lot of chairs and odd shaped gear around while crewing our Leadville 100 runner this year.
Credit: Brandon Lampley

Need to Carry a Bear Canister?

The volume that you choose will also depend on whether you'll need to carry a bear canister. If you will be hiking in California, say you're on the PCT or the JMT, you need a pack that will accommodate a bear-proof food canister for your trips in the Sierra. We tried out each of these packs with a BearVault BV500, the most common size bear canister carried by thru-hikers on the John Muir or Pacific Crest Trails. In some places, bear cans are required by law on these trails.

Smaller bear canisters are available, but it can be challenging to fit food for a week (as well as your cook kit and fragrant toiletries) into these smaller cans. Increasingly, bear canisters are also a great idea on the Georgia to Great Smoky Mountains section of the AT, and again in New York and New Jersey. Canisters are also required by law in at least one short section in Georgia if you stop to camp there.

The Hyperlite Mountain Gear Windrider 3400 is the only recommended pack we tested here that plays nice with the BV500. Similarly, the Gossamer Gear Mariposa fits a bear can pretty well, as it has a slightly wider bottom than the Gossamer Gear Gorilla. If using a full-sized bear can is common on your trips, we highly recommend considering the slightly larger packs made by Gossamer Gear and ULA. The Mountainsmith Zerk 40 is designed to strap a bear canister over top, which is a bit cumbersome but works if you are not predominately planning to travel in bear country.

Do You Want a Lid?

Another consideration when you're thinking about the volume of your ultralight backpack is whether or not you want a lid. A lid or a "brain" is a traditional part of backpacking packs. This pocket on top serves several purposes, but it adds a lot of weight relative to storage space, and many lightweight pack manufacturers forgo a lid in their designs. In general, most of our testers and friends who are focused on very light kits do not use a pack with a lid, or they strip the lid off and leave it at home.

On the other hand, an adjustable lid is a perfect way to strap bulky but light items to the outside of your pack. You can capture your closed-cell foam sleeping pad under the lid. That said, all of the top-scoring packs we tested have other means of lashing a large sleeping pad to the outside. Carrying a climbing rope is one of the few applications that a lid handles much better than side or bottom lashing straps. If you're seeking an ultralight pack that also will double as your climbing approach pack, The North Face Phantom 38 is our top choice. They are also both better at carrying more than 30 pounds than any of the other packs in this review.

How Much Weight Do You Usually Carry?

Most of the packs we tested in this review are more or less comfortable for carrying certain weights. This means that when considering a pack, you should be sure to think about how much weight you think you'll typically be carrying to get a pack that will be plenty comfortable. For loads from 10 to 20 pounds, we think the Arc Blast is the best choice. For loads from 15 to 25 pounds, the Mariposa is the best choice. And for loads from 20 to 35 pounds, the Exos is ideal. These packs are constructed with different types of frames, fabrics, and padding, all of which contribute to their comfort at carrying different weights.

ultralight backpack - only you know how much total weight you need to carry on your trips...
Only you know how much total weight you need to carry on your trips. On the CDT and Colorado Trail this summer, we met happy and successful hikers with total loads from 8 to 40 pounds. Ideal load range varies among the best three packs, each of which has its own niche.
Credit: Brandon Lampley

That said, you may not know how much weight you will usually carry…or you may plan to carry light loads sometimes and medium loads other times. In this scenario, you have three options: 1) Choose a do-it-all pack like the Mariposa that carries both types of loads comfortably but weighs a little extra. 2) Buy two packs (perhaps the Arc Blast and the Exos) to use with light loads and medium loads. 3) Decide that you're willing to sacrifice on comfort when carrying either lighter or heavier loads. In the case of the third scenario, you must ask yourself whether you'd rather have a very light pack that under-performs when carrying medium loads or a heavier pack that handles medium loads well. If you infrequently carry a medium load, or just don't mind the discomfort when it's loaded more heavily, then choosing a very light pack is an excellent option for you.

That said, most of our testers with many thousands of miles under their feet like the compromise of choosing a pack with a frame that is about half a pound or so heavier than the lightest available. Our favorite packs were the ones that are very comfortable with both light loads and medium loads. Our testers were happy to carry a bit of extra weight for the added comfort when their packs were loaded down into the 20s.

The top-scoring Gossamer Gear Mariposa and ULA Circuit are both ultralight packs that may be a little bigger and heavier than you need for your weekend trips, but they have the volume and load-carrying capacity to take you on longer trips, and even into winter.

Other Considerations


If you're an experienced backpacker, you may not find it necessary to try on a pack before you buy it. You've likely worn a few packs before and have a good idea of your torso length and what size option of a pack will fit you the best. Nonetheless, if you want to get your hands on a pack before purchasing, you have a few options. If you spend a fair bit of time out playing in the backcountry, you've likely seen folks wearing most of the packs we tested. Make a new friend and ask to check out that cool pack you're thinking about getting. Many of the packs we tested aren't available from major retailers, so this is a good way to check one out in person.

That said, in the past few months, we've begun to see smaller manufacturers' packs become available in specialty shops. Packs from ULA and Hyperlite Mountain Gear are increasingly carried by a few small shops like Neptune Mountaineering in Boulder, CO (HMG) and Sage to Summit in Bishop, CA (ULA). Visiting an event like Trail Days in Damascus, VA, or a CDT Rockies Ruck, hosted by the Continental Divide Trail Coalition and the American Long Distance Hiking Association-West, is also a great way to check out a large variety of ultralight backpacks from small manufacturers. While most large manufacturer packs are available in just a couple sizes, many cottage industry pack makers offer lots of mix and match options. For example, the torso length of your pack is selected independent of the waist belt size. Visit the manufacturer's website for detailed measuring and sizing information.

ultralight backpack - the granite gear virga 2 and osprey exos 48 peaking out from under...
The Granite Gear Virga 2 and Osprey Exos 48 peaking out from under the beak of the ZPacks Hexamid Twin Shelter.
Credit: Brandon Lampley

Waterproof Cuben Packs

While we usually recommend using both a pack liner and a rain cover, as well as waterproof stuff sacks, when your trips take you to predictably rainy areas, two of the packs we tested offer much greater water resistance than the others. Not only is hybrid Cuben fiber very light, but it is also waterproof. Both the ZPacks Arc Blast and the Windrider from HMG are (for most practical purposes) waterproof. Both also have sealed seams that do a brilliant job of keeping rain from soaking through to the inside of your pack. For a few folks, this is a deciding factor when choosing a pack for very rainy climates. Depending on what items you store in the external pockets, you'll still want a rain cover. Additionally, your most important items inside - sleeping bag and puffy jacket, for instance - should be in waterproof stuff sacks.

Air Flow Suspension

Let's face it, some of us are very sweaty folks and not only when it's hot outside. If this is true for you, we'd recommend choosing a pack with a tensioned frame system that creates airflow between your ultralight backpack and your back and shoulders. Two of our award winners, the Osprey Exos and the ZPacks Arc Blast, have tensioned frames that promote airflow. The North Face Hydra also has this system. That said, we also found the removable "egg-crate" shaped foam back panel of the Editors' Choice Mariposa great at limiting sweaty back syndrome.

ultralight backpack - cruising under spring skies in the zerk 40.
Cruising under spring skies in the Zerk 40.
Credit: Alexa Flower


Armed with this information, we hope we've helped point you in the right direction as you seek out the ideal ultralight pack for your next outing. We also hope that this helps explain the importance of the pack as a part of a larger system - sleeping pad, sleeping bag, and shelter. This helps conceptualize such a small number as a base weight for those just starting down the ultralight path. These packs will certainly work better when combined with other ultralight equipment, though the packs alone are a step in the right direction. Happy trails!

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