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We bought and tested 18 top-rated ultralight backpacks from Gossamer Gear, ULA, Hyperlite, Zpacks, Six Moons Designs, Durston, and more to find the best pack for your needs.
Some of the best Ultralight Backpacks in our stable!
Credit: Justin Simoni
By Justin Simoni ⋅ Review Editor ⋅ Updated November 6, 2025
The right ultralight backpack provides just enough capacity to stash all your basic backpacking essentials while taking a load off your back so you can hike light and fast.
Over the past decade, our thru-hiking experts have logged hundreds of trail miles, testing more than 50 of the best ultralight backpacks around. We slogged along the John Muir Trail, wandered the Colorado Trail and CDT, hiked around Southern France's Haute Alpes, and traversed miles of talus in Argentine Patagonia.
The Gossamer Gear Mariposa is the best pack in our lineup for its ability to manage both light and heavy loads comfortably. The abrasion-resistant material is also durable enough to handle long miles on the trail.
To lighten the load on your wallet, we also love what the less expensive Gossamer Gorilla 50 has to offer. From day hikes to multi-day adventures, this pack provides comfortable straps and a great set of features at a reasonable weight for a more affordable price.
Check out our other reviews of ultralight gear for more ways to shave a few ounces (or pounds) from your pack.
Editor's Note: Our ultralight backpack review was updated on November 6, 2025, to add some new packs from Bonfus, Outdoor Vitals, and 3F.
Main pack fabric less durable than more expensive materials
Against relentless competition from other brands, the Gossamer Gear Mariposa 60 again takes home the award of our favorite ultralight pack. It strikes an incredible balance between comfort and an unparalleled emphasis on lightweight design. Its feature set is thoughtful and useful, but not overkill. The Mariposa offers plenty of external carry options without feeling weighed down by superfluous bells and whistles. It has one of our favorite stretchy center mesh pockets, which proved large enough to store extra layers, snacks, and other items we wanted to access quickly. It fits a bear canister and can carry a heavy load comfortably, yet it can also compress to carry a smaller load comfortably. “Sight unseen, if someone asks me what ultralight pack to grab, I instinctively tell them to grab the Gossamer Gear Mariposa. It works perfectly for just about everyone,” insists main tester Justin Simoni.
SPECIFICATIONS
Measured Weight
34.3 oz
Weight per Liter (Full Pack)
0.57 oz/L
Advertised Volume
60 L
Measured Volume (Main Compartment)
54 L
Stripped Weight
18.0 oz
It's marketed as a 60-liter pack, but we've found that the Mariposa can carry up to approximately 64 liters, if you stuff it to the brim and utilize all of its external pockets. It's not the lightest pack we tested, though its 34.3-ounce total weight and 0.57-ounce per liter weight-to-volume ratio are rather impressive. The tradeoff for a bit of extra weight is an unbeatable level of comfort. The pack's fabric isn't the most durable, and comparatively, some newer packs are starting to look very attractive. If the durability of your pack is of the utmost importance, the Challenge Ultra-sewn packs in our lineup are something to consider: the Durston Kakwa 55, Ultralight Adventure Equipment Ultra Circuit, and Bonfus Framus are all very solid choices.
Great spread of features without compromising on weight
Versatile for day hikes and multi-day trips
CONS
Not as waterproof as other packs
Pack fabrics not as durable as more modern options
Top flap may not be everyone's favorite
Once you get used to the supreme comfort of the Gossamer Gear Gorilla 50, it's hard to imagine living without it. This pack is stacked with features — it has great back padding, an internal aluminum frame, and an excellent hip belt. “I love the Gorilla's voluminous external pockets. They swallow up so much gear that I rarely needed to open the pack's main compartment until it was time to make camp,” our lead tester brags. Even more impressive is the modular design that allows you to customize the pack for the trip's itinerary by easily stripping components off so that you may not need to cut gear weight.
SPECIFICATIONS
Measured Weight
32 oz
Weight per Liter (Full Pack)
0.64 oz/L
Advertised Volume
50 L
Measured Volume (Main Compartment)
45 L
Stripped Weight
16.2 oz
There's little we don't love about the Gorilla, and it will be difficult for anyone to wrangle it out of our greedy thru-hiking hands. Still, the top flap design of Gossamer Gear is unusual in our ultralight category. “Many hikers I know prefer a rolltop design,” claims our tester. If you're especially rough on gear, the mesh on the side and center pockets and for holding the back padding in place may become victims of your heavy-handedness. In that case, the exceptionally durable Dyneema construction of the Hyperlite Mountain Gear Unbound 40 and Hyperlite Mountain Gear Southwest 55 may be better picks, but they're not exactly budget-friendly purchases. If what you seek is an extremely durable pack on an even tighter budget, look into the 3F UL Gear Qidian Pro, which brings many ultralight design ideas to you at a much lower price point. The Qidian Pro provides more than enough internal and external space for long carries at a great volume-to-weight ratio.
Dyneema Composite Fabric is extremely durable and water-resistant
Variety of external pockets
Comfy and embedded foam padding, hip belts, and shaped vertical stay
CONS
No load lifters
Heavier than other packs of similar volume
If you're lucky enough to get to hike a long trail for weeks on end, we highly recommend the Hyperlite Mountain Gear Unbound 40 as an almost perfect pack for the long haul. The extremely durable and water-resistant DCH pack material means you don't have to worry about acute gear malfunction leaving you stranded several states into your long trail. The embedded foam padding, internal shaped stay, and hip belt all work together to support moving pack weight off your shoulders and distributing it onto your hips. “This is one of the most comfortable packs to shoulder at the beginning of a long carry,” lauds our lead tester. The massive exterior center and side pockets allow you to carry much of the gear you'll use throughout the day outside the main pack compartment. A sneaky bottom-of-the-pack stash pocket gives you a few more liters of storage.
SPECIFICATIONS
Measured Weight
34.6 oz
Weight per Liter (Full Pack)
0.87 oz/L
Advertised Volume
49 L
Measured Volume (Main Compartment)
35 L
Stripped Weight
26.0 oz
Comfort, carrying-ability, and convenience come at a cost. For the Unbound 40, it's a few more ounces on the scale when compared to some of the other packs we'd consider when going off the map for a few weeks. The main culprit is the more durable 150-denier polymer face fabric, which provides significant protection against both downpours and abrasive rocks. Also adding some extra weight is the many useful, voluminous pockets you'll find on the Unbound 40. If you don't need a lot of carry capacity, consider a more minimalist pack that utilizes lighter materials. But for us, these included features stopped us from having a frustration-fueled meltdown on the trail more than a few times and allowed us to persevere to our next resupply smiling. “For long-distance trips, the exceptional carrying capacity and the weight transfer to my hips make the Unbound 40 a winner,” said our lead tester. Try out the Ultralight Adventure Equipment Ultra Circuit for another long-distance trail-worthy pack with great storage capacity, comfort, and durability.
We took advantage of the local spring runoff to do an impromptu field test of the Unbound 40's water resistance. After our misogi cleansing, we found the contents of the main compartment to be relatively dry, thanks to the waterproof DCF, taped seams, and our triple folding the roll top.
Requires additional liner for greater water resistance
Adjustment straps can get in the way
For trips that demand a pack with tons of room to store gear, the Six Moon Designs Swift V is the most natural choice. We measured the internal volume at an impressive 55 liters — more than some other packs' total carrying capacity inside and out! A deep, external center pocket, easily accessible side pockets, cavernous hip belt pockets, and a smattering of pockets on the running vest-style shoulder straps round out the extensive carrying capability of this phenomenal high-capacity pack. “I loved the feeling of the Swift V's wide straps hugging my back tightly while I traipsed around,” adds our lead tester.
SPECIFICATIONS
Measured Weight
38.0 oz
Weight per Liter (Full Pack)
0.76 0z/L
Advertised Volume
50 L
Measured Volume (Main Compartment)
55 L
Stripped Weight
27.8 oz
While you will surely shoulder a number of extra backpacking accouterments with the Swift V, there is still a limit on how much weight it can handle comfortably – we suggest keeping loads below 35 pounds. Speaking of weight, as far as ultralight packs go, one with this much main compartment volume isn't ever going to be as light as smaller, more nimble packs. “Some of the features that make the Swift V so comfortable are also what make it just a little heavier than other packs,” notes our tester. If you're concerned about minimizing pack weight while maximizing carrying capacity, check out the REI Co-op Flash Air 50. But in our opinion, the Swift V is the perfect pack when you're the one “lucky” enough to haul you and your partner's favorite two-person tent, or you need to bring along a bulkier, 0-degree sleeping bag for a chilly night in the alpine. It is an amazingly comfortable, do-it-all pack for long carries.
We are totally blown away by the amount of engineering put into the exceptional Osprey Exos Pro 55, which takes a conventional backpack design and reworks it to make it truly ultralight. Weight may be gone, but all the creature comforts that one expects from a backpack are not left on the cutting room floor. “I especially loved the back suspension system on this pack. It provided comfort from my pack's load and gave a ton of air circulation that my sweaty back desperately craves,” says our head tester, Justin Simoni.
SPECIFICATIONS
Measured Weight
33.2 oz
Weight per Liter (Full Pack)
0.60 oz/L
Advertised Volume
55 L
Measured Volume (Main Compartment)
46 L
Stripped Weight
30.4 oz
If you're the type who likes to strip your pack down to cut as much weight as possible, this likely isn't your pack. The frame, padding, and hip belts aren't removable (although the top lid is). “Save this pack for your long hauls and use a more nimble pack for day trips,” our lead tester recommends. Still, you can certainly make a proper sub-ten-pound base weight kit when using the Exos Pro, and for that, we applaud Osprey's design. The main nylon fabric is built to last for years, but the back mesh on the suspension system might need to be babied a little more. The REI Flash Air 50's back padding reminds us of more conventional packs it but features a very light main pack body. The main difference between the two is that the Flash Air 50 is a roll-top style and lacks a removable brain altogether.
Going lighter often means starting out from the trailhead with simpler gear and a little more knowledge on how to best use what you've brought along. For discriminating ultralight tastes, we have the The Cutaway from Nashville Pack, an expert's pack with very impressive stats. This 40-liter pack keeps its weight-to-volume ratio low by forgoing an internal frame and padding. “Without padding, I recommend packing this rig strategically so that nothing pokes you in the back,” says our tester. If you've dialed in your sleeping system and shelter setup, then The Cutaway could be the cherry on top of your ultimate UL kit.
SPECIFICATIONS
Measured Weight
22.0 oz
Weight per Liter (Full Pack)
0.40 oz/L
Advertised Volume
40 L
Measured Volume (Main Compartment)
43 L
Stripped Weight
17.3 oz
The Cutaway's shoulder strap system and external pockets are both ahead of the game and good enough reasons to suggest this pack to almost anyone. However, frameless packs can be a bit polarizing – not everyone's back and shoulders are going to agree with the lack of traditional support. “I usually rig up my foam sleeping pad to the back of this pack for extra comfort,” our lead tester shares. “But it is one more step I need to do before I get going for the day.” For a little more convenience, consider the Zpacks Arc Haul Ultra as a suitable alternative. It's another excellent pack targeted at skilled long haulers, just with a frame design that helps move some of the load off your shoulders and keeps air flowing across your back. But if you're already sold on the idea of the frameless pack, then look no further than The Cutaway.
Excellent running vest-style shoulder straps with ample pockets
Tapered center mesh pocket retains gear
CONS
Not great with heavy loads
Limited external daisy chains or tie-off points
There are many details we love about the Black Diamond Beta Light 45, from its tough yet lightweight Ultra 200 fabric to its running vest-inspired shoulder straps (with all those easy-to-access pockets!) But what surprised and delighted us the most was just how versatile and modular the pack design was for different trips. We could use all of the built-in features for heavier loads or strip them off when going fast and light – the latter being what this pack is best for. This pack weighs only 19 ounces when fully stripped, yet still boasts 40 liters of internal capacity and more than 10 liters of external carrying capacity. “For newer ultralight backpackers, this pack offers lots of options to work with while dialing in your preferences and perfecting your systems,” notes our lead tester. “This is a pack that'll grow with the owner.”
SPECIFICATIONS
Measured Weight
31.7 oz
Weight per Liter (Full Pack)
0.70 oz/L
Advertised Volume
45 L
Measured Volume (Main Compartment)
40 L
Stripped Weight
19.0 oz
Unfortunately, this Transformer of a pack isn't great at carrying heavy loads, and we struggled to carry much more than 35 pounds. The main problem is that the Beta Light 45 doesn't transfer pack weight to the hip belt as well as other packs we tested. The vest-style shoulder straps and sternum strap have a bit of stretch to them, which is great for moving quickly (and even running) but not so great for carrying out a seven-day load. Our lead tester adds some insight: “This pack may appeal to those who like how their running vests and day packs feel and want to capture that in their Ultralight pack.” For high mileage, long days, and lighter loads, the BD Beta Light 45 will support your performance-oriented goals.
The banana-shaped right front pocket on the Beta Light 45 securely fits our phone for easy access to messaging and navigation.
Credit: Justin Simoni
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The burning in our legs from the incredible climbs is worth it for the views!
Credit: Justin Simoni
How We Tested
Our testing process always begins with in-depth research into the market to identify the very best products out there. After we make our selection, we purchase all the products at retail prices to eliminate bias from our reviews. Our ultralight backpack testing protocol consists of both lab testing and miles upon miles on the trail. We independently verify weight and volume measurements. Then, we take it a step further by scoring packs based on their weight per unit volume, allowing us to compare different volumes fairly. Our on-trail testing is where we really put these packs to their paces. We've taken Winter expeditions on the Appalachian Trail, summers on the Colorado Trail, our own version of the “Argentine Spine” alt on the CDT, and completing the arduous Sangre de Cristo Range Traverse in Colorado. We spent time in Patagonia, the Continental Divide Trail, and the Sierra High Country. Additionally, we made direct comparisons using 15 and 30-pound weights for shorter test laps around our local trails in Boulder, CO.
Our ultralight backpack testing is divided into four different metrics:
Comfort (40% of overall score weighting)
Ease of Use (25% weighting)
Weight-to-Volume Ratio (20% weighting)
Adjustability (15% weighting)
Why Trust GearLab
This review is the result of the combined efforts of several GearLab ultralight experts. Justin Simoni has led the review for the past few seasons. He lends his deep knowledge and vast experience gained from his time in the Colorado backcountry, as well as guiding in California and Alaska. Simoni has done fast-and-light missions following the true ridges of the Continental Divide, the Sangre de Cristo Range, and the Mosquito-Tenmile Range. With no external support, he has summited all the Colorado 14ers and Centennials in two separate years. He can be heard quietly musing about giving an unsupported FKT (fastest known time) of the Colorado Trail another go after his daily high-elevation-gain trail runs. Jane Jackson and Brandon Lampley bring to the table a wealth of related experience. For 200+ days a year, you can find Jane outside using and testing gear. With years spent working and playing in the Yosemite backcountry, the Tetons, and the Wind River Range, as well as trips taken to the Alaska Range, the Himalayas, and Patagonia, she has spent plenty of time under the burden of a heavy pack. Brandon has hiked both the Pacific Crest Trail and the Appalachian Trail, essentially back-to-back, with only four months off in between. He also has first ascents to his name in the Indian Himalayas and has summited Denali and Ama Dablam.
We took all these packs on a variety of outdoor adventures to help you find the best pack for you.
Analysis and Test Results
Over the past decade, we've tested hundreds of backpacks of all styles. The products we've included in this review represent the cutting edge in ultralight technology. If you're looking for larger frames and luxury padded waistbelts, look elsewhere; the packs in this review hardly resemble a traditional backpacking pack. Many exciting small brands have popped up in this category of outdoor gear over the past few years, as well as strong options from larger brands. We've had fun assessing their latest products. Here, we evaluate the top products available for multi-month thru-hiking adventures and shorter alpine trips focused on fast and light backcountry travel.
Worse Value
Better Value
What's the Best Value?
When making an outdoor gear purchase, we often trade off one thing for another, and no one understands trade-offs better than an ultralight enthusiast. We all spend too much time “weighing” our options. Bringing a slightly thicker sleeping pad can mean foregoing powdered milk in the coffee - decisions, decisions. However, ultralight packs continue to get better and more comfortable as time passes.
Side pockets are easy to access and a perfect place to stash on-the-go snacks. Well-designed features that work are one of the big reasons why we think the Hyperlite Mountain Gear Unbound 40 delivers good on value.
Credit: Justin Simoni
The Gossamer Gear Gorilla 50 offers very impressive comfort and versatility for a reasonable price. The Gossamer Gear Mariposa 60 isn't much more expensive and is also our favorite all-around ultralight backpack. Alternatively, the ULA Ultra Circuit is more expensive but is also made of more durable materials designed to last for a long time through trying conditions. The Durston Kakwa 55 is one of our lineup's most dialed-in ultralight packs at an excellent value.
Not only is the Gorilla 50 highly functional, its value shines when you compare its price to many of the other overall high-scoring ultralight packs we tested.
Credit: Justin Simoni
If you're starting your ultralight trek on a serious budget, consider the 3F UL Gear Qidian Pro. It has a ton of the features you're probably looking for in an ultralight pack, including durable ripstop material, a sleeping pad sleeve and frameless design, deep center, side and hip belt pockets, a ton of internal volume — all for a price less than half as much as other packs. Price is kept lower partly because of the use of slightly heavier nylon ripstop material, rather than exotic laminates.
The 3F UL Gear Qidian Pro has some compelling features for such an inexpensive option, including a sleeping pad sleeve for back padding and generous amounts of space in the center, side, and hip belt pockets.
Comfort
Of course, we all want an ultralight pack to be featherlight, but it must carry our load comfortably to be worth it. For each of these packs, we judged load-carrying comfort for two loads: 15 and 30 pounds. We then averaged each pack's performance in both categories to generate our carrying comfort score.
Fifteen pounds is a perfect comparison weight for ultralight hikers on a short trip. Thirty pounds is a fair comparison weight for lightweight hikers on shorter trips, ultralight hikers carrying a week's worth of food, or those brave enough to travel in the winter. While some packs can be stripped of their frame and waist belt, our evaluation of “great, good, or poor” for carrying 15 and 30 pounds is with the frame and waist belt in use, as these features add significantly to the comfort of carrying a pack. We only recommend stripping down a pack completely when carrying 12 pounds (or less) in total weight.
Not everything about trudging through the backcountry is comfortable, but your pack should be!
Credit: Justin Simoni
The Most Comfortable Packs by Weight
To simplify our findings for load-carrying comfort even further, we've broken down some of our award winners' niches as far as load-carrying comfort goes:
Best for 10-20 lb loads: Pa'lante V2
Best for 15-25 lb loads: Gossamer Gear Gorilla and Mariposa
Best for 35+ lb loads: Six Moon Designs Swift V, Hyperlite Mountain Gear Unbound 40, and Hyperlite Mountain Gear Southwest 55
The Gossamer Gear Mariposa 60 and Gorilla 50 are two of the most comfortable packs we've ever tested. The main difference is that the Mariposa offers a bit more internal capacity for only a tiny weight penalty. With hip belts attached and back pads on, these packs are well-balanced and secure to carry. For carrying loads under twelve pounds, they are also some of the easiest packs to strip off their frame and waist belts without sacrificing any amount of comfort.
The tensioned carbon rods and mesh backing of the Zpacks Arc Haul Ultra help to support your load while still letting air flow around your back.
Credit: Justin Simoni
The Osprey Exos Pro 55 is nearly as comfortable as either of the Gossamer Gear packs, but for different reasons. Its tensioned mesh back panel and wrap-around, non-removable hip belt help to distribute weight far better than most other solutions in the ultralight world. A similar philosophy is employed on the svelte Zpacks Arc Haul Ultra. Adjustable, tensioned carbon rods bow the back panel to conform to the shape of your body while at the same time providing a sprung, hammock-like surface to improve airflow.
In addition to offering a ton of up-front storage space, the Swift V's running vest-inspired shoulder straps hug your body for a more secure carry.
Credit: Justin Simoni
The running vest-inspired design of the Six Moon Designs Swift V does an excellent job of hugging the pack close to your body to reduce bounce. The removable, internal hoop stay and wide hip belt also provide enough support and rigidity to carry heavier loads. The pack is designed so that only the center column rests against your own back, helping maximize airflow. If running vest-inspired packs are attractive, the Black Diamond Beta Light 45 and Nashville Pack The Cutaway also offer some serious comfort with their own take on this design. Though unlike the other two, The Cutaway is a frameless pack, so overall comfort is entirely dependent on how you pack your rig.
The padding throughout the lumbar region of the Unbound 40 makes this pack incredibly comfortable, and the belt is still removable to shave weight or swap for a different size (which are sold separately).
Credit: Justin Simoni
The Hyperlite Mountain Gear Unbound 40 also scored well, thanks to its cushy built-in back padding, which helps keep your gear from poking you with every step. The single curved back stay is removable to tweak the shape to better suit the curvature of your back or if you want to take it out completely. Despite all of the other features, it's interesting the Unbound lacks load lifters. Load lifters are often a nice addition to larger packs to adjust how the pack weight is distributed. If this is a point you're unwilling to compromise on, the REI Co-op Flash Air 50 has some of the best of any pack we tested.
Simple yet effective load lifters like what's found on the REI Co-op Flash Air 50 can help adjust how the pack sits on your upper back, making it easy to dial in the fit even on the go.
Credit: Justin Simoni
If a top-notch internal frame in your pack is an absolute non-negotiable even for carrying comfort of smaller weight loads, have a close look at the Outdoor Vitals CS40 Ultra. Its internal frame and built-in padding, along with excellent load lifters, are hard to beat for carrying the 40 liters of internal volume we measured. The slimmer pack profile helps keep gear weight closer to your own center of gravity.
The Outdoor Vitals CS40 Ultra makes a comfortable pack even for lighter loads if you or your tired back prefer an industry-leading internal framed system.
Credit: Justin Simoni
The Bonfus Framus is also another standout pack when seeking out a comfortable carry. Its well-designed removable internal stays and EVA padding make it a joy to use, even at its manufacturer's stated maximum carrying weight of 40 pounds.
The internal frame of the Bonfus Framus is removable. It's comprised of two aluminum stays and EVA padding.
Ease of Use
How easy is it to use the features of the pack? What's the point of a specialized pack if you need an advanced degree in spatial awareness to use it? We used every pocket repeatedly to assess their convenience, ease of access with and without removing the pack, and versatility for various types of trips and packing styles.
The Osprey Exos Pro 55 delivers every time we really need to get up and get going. This pack is very “Batteries Included,” with many of the features we like already incorporated, for only a small weight penalty. If you're transitioning to ultralight from a more conventional backpack, this pack makes the transition utterly painless.
We love the side pockets on the Osprey Exos Pro, which are easily accessible even while wearing the pack.
Credit: Justin Simoni
The Gossamer Gear Gorilla and Gossamer Gear Mariposa also get high honors for ease of use. Both are intuitively designed, making it easy to just throw them on your back, yet both have the features we like to see in more advanced packs. Standout details include the voluminous center pocket, which can hold most everything we need for the day, like every stitch of clothing we'd need from sun-up to sun-down, keeping us from having to open up the main compartment to rummage around for what we're looking for.
The Gossamer Gear Gorilla 50 delivers a ton of value for the features it offers, and was our choice for a particularly adventurous alternative on the CDT through the hinterlands of Colorado.
Credit: Justin Simoni
Not to be totally outdone by the packs above, the REI Co-op Flash Air 50 is also a great option for folks transitioning to an ultralight pack. The Flash Air takes a lot of design cues from its more conventional cousin, the REI Co-op Flash 55, including its particularly deep side pockets.
Each side of the REI Co-op Flash Air 50 actually has two pockets, with the smaller one designed to be reach easily to grab items like water bottles while you're on the go.
Credit: Justin Simoni
The Hyperlite Mountain Gear Unbound 40 seems to take the correlative approach, borrowing some of the best features found in a spectrum of standout UL packs, then assembling those features into an all-star pack. We loved the easy-to-access side pockets, bottom stash pocket, and of course, its stealthy DCH pack material.
The side pockets of the Unbound 40 are some of our favorites because they're accessible to us while on the move.
Credit: Justin Simoni
The Durston Kakwa 55 also has some well-thought-out features and pockets that are a joy to use. We particularly like the zippered stash pocket found within one of the side pockets to allow us to securely keep very important items, like keys and cards.
The Durston Kakwa 55 comes ready out of the box to help support you on your next long distance hike.
Credit: Justin Simoni
The Granite Gear Crown3 60 has a lid with a brain for those folks who love that feature. It can also fit five Smartwater bottles in each of its side pockets. The ULA Ultra Circuit is also impressive, though it holds just four 700-milliliter Smartwater bottles in each of its side pockets. The Gossamer Gear Gorilla and Mariposa, Osprey Exos Pro, Southwest, Unbound 40, REI Co-op Flash Air 50, and Pa'lante V2 all have whistles attached to their sternum straps.
The Pa'lante V2 includes a built-in emergency whistle on its sternum strap.
Weight-to-Volume Ratio
The weight-to-volume ratio is a measurement used to compare packs of differing volumes. This metric starts with objective measurements: how much does this pack weigh relative to the volume it carries? We measured the weight of each model on our digital scale and the volume of the main compartment.
We measured internal pack volume, as well as the volume of the main exterior pockets. This gives us a normalized way to compare packs from different manufacturers using the same rules. Most pack makers are honest with the volume numbers they advertise. However, pack capacity, in liters, is sometimes different than the number used in the product name. So we suggest buyers look a little more closely into the specifications of the packs to make sure they understand how manufacturers are calculating their volume numbers – you'll often see internal and external volumes advertised.
The Hyperlite Mountain Gear Southwest 55 was found to have an internal volume of 49 liters -- one of the most voluminous packs we measured.
Credit: Justin Simoni
How Do We Measure Volume?
To measure the internal volume of a backpack, we use hundreds of ping pong balls, which are an easy-to-source substitute for the smaller-diameter 20mm balls used in the standardized industry test. We stuff as many as possible into the main compartment, ensuring that we can still securely close the pack. We then use a trash can-turned-giant graduated cylinder to measure the volume of ping pong balls. The larger-diameter ping pong balls may not be quite as accurate as the standardized test, but we've found this test is a worthy means of verifying manufacturer's claims. The ping pong ball test is especially useful for comparing products from different manufacturers, as everyone seems to measure their packs in a different way. We've run this test for years, and we're confident our system of measurement is precise to +/- 3 liters.
We measured the Durston Kakwa 55 as having approx. 45L of internal storage in the main compartment when stuffed with ping pong balls to the point of bursting, then rolled down and secured.
Credit: Justin Simoni
For external pockets, we'll use a variety of common items to get a feel of their carrying capacity. Oftentimes external pockets are open-ended, so the exact volume is difficult to report, as what constitutes the pocket being “full” is subjective. For center and side pockets, we normally use Smartwarter bottles; for hip belt pockets, we use Clif Bars.
We utilize Smartwater bottles for external side, center, and bottom pockets, as well as Clif Bars for hip belt pockets, to give you a visual idea of the carrying capacity of these pockets.
But numbers only tell part of the story. We also consider what each pack's weight gets you in terms of durability. After all, a superlight pack that tears the first time you scrape it across a boulder isn't worth all that much. We scrutinized and compared fabrics, seams, and components like zippers and buckles. We researched common complaints for each pack to see if we had the same sorts of issues during our weeks spent in the backcountry. By pulling both objective measurements and subjective observations from our expert testing team, we created a complete picture of the value each pack offers, corresponding with its weight-to-volume ratio.
Ping pong balls ruled the roost when measuring the internal volume.
Credit: Justin Simoni
When we calculated the weight-to-volume ratio to compare each pack directly, regardless of volume, we got a comparable idea of how light these packs really are. All the packs in the ultralight category fared extremely well when looking at their weight-to-volume ratios, but there certainly are some standouts.
If you're moving fast through harsh terrain, ULA packs, like the Ultra Circuit, are made entirely of Ultra fabrics, which makes them super durable and more water resistant.
Credit: Justin Simoni
The Challenge Outdoor Ultra family of composite materials comes up often when we look at packs with excellent weight-to-volume ratios, as these materials are incredibly durable while maintaining low weight. They're also very water resistant, which means you may think about setting off from the trailhead without a pack liner, saving even more weight.
The incredible Ultra 100X material of the Zpacks Arc Haul Ultra is some of the thinnest and lightest around, especially for how strong it is.
Credit: Justin Simoni
The Zpacks Arc Haul Ultra opts for extra-lightweight Ultra 100X fabric for the main body along with a carbon fiber frame. This delivers a pack with 35 liters of internal capacity, along with a giant center mesh pocket, at an incredible 0.44 ounces per liter. But the Arc Haul Ultra isn't alone; packs that stand out for their Ultra materials abound in our lineup. The full Ultra 200X Durston Kakwa 55 comes in at a very respectable 0.42 oz/L. The more abrasion-resistant Ultra 400x bodies on the Ultralight Adventure Equipment Ultra Circuit and Black Diamond Beta Light 45 come in at 0.53 oz/L and 0.70 oz/L, respectively. Not to be outdone, the Bonfus Framus was measured with 55L of internal volume and a 0.46 oz/L weight-to-volume ratio. Its use of white Ultra 200X really shows off its maker's amazing attention to detail in sewing and seam taping. The slightly higher weights of the above packs also tend to correspond with additional features.
Stripped of many of its optional accessories and by rolling the roll top down tightly, the Black Diamond Beta Light 45 makes a fairly good day pack.
Credit: Drew Crittenden
But Challenge Ultra isn't the only game in town. If you're looking to save a little weight and money on your next ultralight pack purchase, there are some other compelling fabrics out there. The 18.6 ounce Pa'lante V2 is made with a strong, lightweight, and cost-effective Nylon 210D UHMWPE Gridstop. This pack and material boasts a 0.5 ounces per liter weight-to-volume ratio (and that's only counting the pack's internal capacity! Side, center, and a bottom stash pocket carry even more gear.
The thin yet tough 210d UHMWPE gridstop used in the Pa'lante V2 is plenty strong for long distance duties.
With a weight-to-volume ratio of 0.55 ounces per liter, we also hold the Nashville Pack The Cutaway in high regard, namely because the 21-ounce pack weighs significantly less than most of the other 40-liter packs in our lineup. This is a highly customizable pack and we opted for the default Venom Gridstop ECO pack material — similar to the Pa'lante. The Granite Crown3 has a similar ratio of 0.53 oz/L and is a particularly great choice if you're shopping on a tighter budget, although the nylon fabric lacks the UHMWPE gridstop. You can even cut down on some of the included features to save additional weight.
The Granite Crown3 has a ton of internal storage in a lightweight package.
Credit: Justin Simoni
Adjustability
Adjustability tests how well a pack fits your own body, adapts to all the different adventures you may go on, and how well it carries the usual suspects of backpacking gear. We asked ourselves: Is this pack working with or against us in all the trips we want to bring it along for? We also considered the sizing and customization options that were available during the ordering process.
Ultralight backpacks used to have a sour reputation of not accommodating a wide range of body types, unless you wanted to drop some serious cash on a custom rig. Not anymore. Pack makers are now developing innovative ways to make their packs more adjustable as well as adding a wider spectrum of sizes, making their packs more accessible and comfortable than ever before.
The shoulder straps on the Granite Virga3 accommodate an incredible range of both torso height and width.
Credit: Justin Simoni
The Granite Gear Crown3 60 features a hyper-adjustable hip belt that can be extended to cover multiple conventional belt sizes. This belt can also be paired with the Crown3's removable lid to become a hip pack for day trips away from base camp.
Nashville Pack's The Cutaway features a clever shoulder strap attachment system that allows you to swap different lengths, as well as adjust the width and angle at which the straps are attached to the pack.
Nashville Pack offers an impressive list of options to customize The Cutaway before it even gets shipped to you. Pick the torso length of the pack, as well as the perfect shoulder strap length to accommodate your own body. (Don't worry, Nashville Pack provides clear instructions to help you make these decisions.) Once you have the pack in hand, you can choose where to attach the shoulder straps to accommodate wide and narrow shoulders, and you even have the option to switch them out for different shoulder straps in the future.
Torso length is easily adjustable on the Six Moon Designs Swift V, helped in part by the optional tool included with the pack.
Credit: Justin Simoni
Similarly, Six Moon Designs offers three different shoulder strap styles for the Swift V: running vest, conventional, and S-curve. We chose to test the Swift V with the running vest-style shoulder straps because they offer additional large pockets and an excellent fit. You can adjust the pack's torso length to dial in the perfect fit or even easily adjust it for a friend if you lend it out. Torso length adjustability is also a core feature of the Osprey Exos Pro 55, which is nice considering the mesh back panel.
The built in torso length adjustment of the Osprey Exos Pro 55 is one of its best features.
Credit: Justin Simoni
Many packs are modular in design, allowing you to forgo many of the optional elements. This gives you the superpower to pare the pack down for weight savings, make it more appropriate for shorter trips, and allow you to grow with the pack as your own ultralight backpacking experience matures. The Gossamer Gear Mariposa and Gossamer Gear Gorilla both scored highly for adjustability, with an incredible amount of modularity in both of their similar designs, which allows them to be worn comfortably — depending on load — with or without their back padding, internal frame, or hip belt. Both of these packs can also be purchased with “mix and match” hip belts, allowing you to order your perfect combination of sizes. This customization is also available for the Ultralight Adventure Equipment Ultra Circuit and Ultralight Adventure Equipment CDT.
Both the Gorilla and Mariposa have removable back padding, internal frame, and hip belt.
Both the Black Diamond Beta Light 45 and Hyperlite Mountain Gear Unbound 40 are also designed to be stripped of their hip belt, internal stays, and compression straps for very fast and light adventures when carrying lighter loads. The Beta Light can also have its minimalist back padding removed.
Both the Hyperlite Mountain Gear Unbound 40 and Black Diamond Beta Light 45 are designed to be modular, so you can take off parts for a lighter load at the expense of carrying weight limit and comfort.
Other Notable Ultralight Backpacks
These days, hikers are spoiled with the number of excellent choices in ultralight backpacks. Here are a few that we've highlighted in the past, which haven't quite made the current cut:
Hyperlite Mountain Gear Porter 55 — This is an absolutely excellent pack that can be augmented for many different light-and-fast missions by adding and removing modular accessories of your choice to its exterior via the generous amount of daisy chains found. But for dedicated ultralight backpacking, the lack of built-in center and side pockets makes this pack less useful than some other options from Hyperlite, like their Southwest 55 and Unbound 40.
Ultralight Adventure Equipment Ohm 2.0 — The Ohm is an excellent pack for just about everyone. However, the total weight is on the heavier side for the maximum 30 pounds the manufacturer specs as the comfort limit. We've still kept the Ultralight Adventure Equipment CDT as it's an excellent pack at a great price.
Ultralight Adventure Equipment Circuit 68 — Another strong contendor from ULA. We feature the Ultra Circuit in our current best-in-class lineup, as it has all the goodness of this pack, with upgraded Ultra X pack materials. The Circuit 68 is still an excellent pack to consider if the Ultra Circuit doesn't fit your budget.
LiteAF Multi-Day 35L Frameless — A simple, no-nonsense design makes this pack speak to ultralight aficionados who know how best to pack for its frameless design. The LiteAF just may not pack enough features into its simple design to spar with our current highlighted lineup.
Mountain Laurel Designs Exodus 55L — A winning weight-to-volume ratio, coupled with the excellent Ultra 200X pack material, really sets the Exodus apart. Unfortunately, the excellent specs are at least partly accomplished by stripping features to their minimum, making its ease of use, comfort, and adjustability scores suffer. However, for expert backpackers seeking a light-and-fast pack, the Exodus 55 is still a top contender.
Homiee 50L with Rain Cover - We were hoping the Homie would make a compelling budget offering, even as a pack you keep stowed away in your car for spontaneous trips, but it just didn't perform well enough for anything but the lightest of uses.
Where will your perfect ultralight backpack take you?
Credit: Justin Simoni
Conclusion
We hope the information in this review sparks an interest in the ultralight world. If all the gear required feels overwhelming, simply getting a lightweight pack is a wonderful place to start. A light pack automatically jumpstarts the transition toward lightening up the rest of your kit. The packs in this review range from extremely slimmed down to more comfy options for those unwilling to part with the standard backcountry creature comforts. Our testers have worn loads of different packs within and outside the ultralight world, bringing a breadth of experience to help guide you toward the pack that is right for you.
