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We purchased and tested 16 of the best ultralight backpacks from Gossamer Gear, Durston, Hyperlite, Zpacks, Six Moons Designs, ULA, and more to help you find the perfect pack for your next adventure
Some of the best Ultralight Backpacks in our stable!
Credit: Justin Simoni
By Justin Simoni ⋅ Review Editor ⋅ Updated June 10, 2026
The best ultralight backpack is the one that's comfortable enough to wear for days on end, offers enough carrying capacity for a thru-hike, and is lightweight enough to keep your base weight to a minimum.
The Gossamer Gear Mariposa 60 is the best ultralight backpack on the market. It comfortably carries both light and heavier loads, and the abrasion-resistant material is durable enough to handle long miles on the trail.
The more affordable Durston Kakwa 55 also tops our list. It's a particularly well-designed pack built from bombproof materials and featuring an internal frame for added comfort.
Over the past decade, our thru-hiking experts have logged hundreds of trail miles and have tested more than 50 packs. We slogged along the John Muir Trail, wandered the Colorado Trail and the Continental Divide Trail, hiked around Southern France's Haute-Alpes, and traversed miles of talus in Argentine Patagonia.
For this review, we purchased and tested 16 of the best ultralight backpacks on the market. We tested them side by side to compare their overall performance and value, so you can easily find the perfect one for your needs and budget.
Editor's Note: We updated our review of ultralight backpacks on June 10, 2026, adding new reviews for packs from Durston, Zpacks, Black Diamond, Bonfus Framus, ULA, Pa'lante, Outdoor Vitals, Granite Gear, REI, and 3F UL Gear.
Fabric is less durable than more expensive materials
SPECIFICATIONS
Measured Weight
34.3 oz
Stripped Weight
18.0 oz
Advertised Volume
60 L
Measured Volume (Main Compartment)
54 L
Weight per Liter (Full Pack)
0.57 oz/L
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 down to carry a smaller load pleasantly. “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 our main tester.
It's marketed as a 60-liter pack, but we've found that the Mariposa 60 can carry up to 64 liters if you stuff it to the brim and use all 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, by comparison, some newer packs are starting to look very attractive. If the durability of your pack is of utmost importance, the Challenge Ultra-sewn packs in our lineup are worth considering: the Durston Kakwa 55, Ultralight Adventure Equipment Ultra Circuit, and Bonfus Framus 58L are all very solid choices.
The Durston Kakwa 55 is a nearly perfect ultralight pack at an unbeatable price. It offers exactly what you want for long-distance trips, from its cavernous main compartment and large external pockets to the tough Ultra 200X pack fabric that's highly abrasion, puncture, and weather-resistant. “The Kakwa 55 doesn't try to include every feature under the sun,” explains our lead tester, “instead including the most useful ones, like an internal frame and easy-access shoulder straps, to save on pack weight while delivering a highly functional pack.” With a svelte base weight of 31 oz, even with the internal frame and back padding, the 55-liter Kakwa is one of the most comfortable, high-capacity packs we tested – not to mention, one of the most affordable.
Ultralight gear is always a game of compromises, and the Kakwa 55 is no exception. The Ultra 200X fabric is extremely water-resistant, which is excellent for afternoon thunderstorms, but not great for ventilation. The Ultralight Adventure Equipment Ultra Circuit is another high-capacity hauler with much better airflow across your back, but it's also much more expensive. The front shoulder pockets on the Kakwa 55 are useful, but we'd love them to be just a little bit bigger to better accommodate 500 ml water bottles. While you now have the option to choose your hip belt size independently of torso size, the belt is sewn in and isn't removable, making this pack less versatile for day hikes or quick overnighters. The similarly sized and priced Six Moon Designs Swift V solves both of these issues, but it's not nearly as streamlined as the Kakwa 55. As we said, there are always compromises, but Durston Kakwa 55 strikes the best balance of almost any pack we've tested.
Comfy foam padding, hip belts, and a shaped vertical stay
CONS
No load lifters
Heavier than other packs of similar volume
SPECIFICATIONS
Measured Weight
34.6 oz
Stripped Weight
26.0 oz
Advertised Volume
49 L
Measured Volume (Main Compartment)
35 L
Weight per Liter (Full Pack)
0.87 oz/L
If you're lucky enough 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 move weight off your shoulders and distribute it to your hips. “This is one of the most comfortable packs to shoulder at the beginning of a long carry,” our lead tester lauds. 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.
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 much carrying capacity, consider a minimalist pack that uses 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. Credit: Justin Simoni
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 capacity 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.
While you will surely shoulder a number of extra backpacking accouterments with the Swift V, there is still a limit to how much weight it can comfortably handle – 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 your and your partner's favorite two-person tent, or when 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.
If you're the type who likes to strip your pack down to cut as much weight as possible, this likely isn't the pack for you. 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 with 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 in the suspension system might need a little more care. The REI Flash Air 50's back padding reminds us of more conventional packs, 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 about how best to 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.
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 will 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 shift 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.
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
SPECIFICATIONS
Measured Weight
31.7 oz
Stripped Weight
19.0 oz
Advertised Volume
45 L
Measured Volume (Main Compartment)
40 L
Weight per Liter (Full Pack)
0.70 oz/L
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 stripped down, yet still boasts 40 liters of internal capacity and more than 10 liters of external 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.”
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, which is great for moving quickly (and even running) but not so great for carrying 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
Product Comparison Table
The burning in our legs from the incredible climbs is worth it for the views! Credit: Justin Simoni
How We Tested
We use the same test plan for each update to better compare all of the products. Our protocol is defined by extensive field time and supported by close examination in the lab. 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 fairly compare different volumes. We then hit the trail to assess key characteristics such as comfort, ease of use, and adjustability. We've walked the Appalachian Trail (AT) in winter and the Colorado Trail in summer. We've spent time with these packs in Patagonia, along the Continental Divide Trail (CDT), on week-long trips in the high Sierra of California, and on fastpacking overnighters near Boulder, Colorado.
Our ultralight backpack testing is divided into four different metrics:
Justin Simoni leads our review team. His deep knowledge of ultralight gear systems is rooted in his time in the Colorado backcountry. Some of his favorite adventures include traverses of the Sangre de Cristo Range, the Mosquito-Tenmile Range, and huge chunks of the spine of the Continental Divide. He's summited the Colorado 14ers (twice), both times by pedaling his bike to the trailheads self-supported. He's guided backpacking trips in California and Alaska, and also works as an educational ambassador for a mapping software company used by Search and Rescue.
We took all these packs on a variety of outdoor adventures to help you find the best pack for you.
Analysis and Test Results
For more than a decade, we've tested dozens upon dozens of ultralight backpacks– the products you'll find in this review represent the very finest in ultralight design and technology. We don't accept freebies from manufacturers because we feel it's vitally important to offer you an honest assessment of the best packs on the market.
If you're looking for a conventionalbackpacking pack, you've come to the wrong place. The backpacks in this review may bear a slight resemblance to their more robust peers, but the ethos of an ultralight pack is simplicity and minimalism. While comfort is still paramount, the goal is to travel with as little weight as possible. While many of these packs come from smaller, cottage brands, some more name brands have responded in recent years – all the better for us, as we now have an incredible selection of ultralight packs to choose from.
Worse Value
Better Value
What's the Best Value?
With made-to-order, bespoke options available from plenty of brands, the sky really is the limit. Value here isn't about finding the least expensive possible pack that may get you through your trip, but rather about finding a great balance of features and performance at a fair price. To that end, we turn your attention to the Durston Kakwa 55, a true ultralight design with few frills and bombproof construction. For the price, it's easy to recommend this pack for beginners and experienced backpackers alike.
The Kakawa 55 proved to be an excellent value, with great comfort and excellent durability. Credit: Justin Simoni
The similarly priced Gossamer Gear Gorilla 50 is even a bit more comfortable than the Kakwa 55. While the specialty Ultra 200X fabric on the Kakwa is lighter-weight and more durable than the standard Robic Nylon on the Gorilla, this pack is more adjustable, which may make it a better choice for some people.
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 out 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, all at a price less than half that of even the reasonably priced Kakwa 55 and Gorilla 50.
The price alone makes the simple 3F UL Gear Qidian Pro a compelling option. Credit: Justin Simoni
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 pack, we assessed load-carrying comfort at 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 conducted with the frame and waist belt in use, as these features significantly enhance pack comfort. 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
When purchasing an ultralight backpack, see if the manufacturer states a maximum load limit they consider appropriate. Choosing a pack by minimum weight alone isn't very helpful if it has an equally low load limit.
Here's a breakdown of some of our award winners by carrying capacity:
Best for 10-20 lbs: Pa'lante V2
Best for 15-25 lbs: Gossamer Gear Mariposa 60, and Durston Kakwa 55
Best for 35+ lbs: Six Moon Designs Swift V, and Hyperlite Mountain Gear Unbound 40
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 12 lbs, they are also among the easiest packs to strip off their frames and waist belts without sacrificing any comfort. The Gorilla and Mariposa are spec'd by the manufacturer with a max load limit of 30 lbs and 35 lbs, respectively.
The Arc Haul can securely take a heavier pack weight, and still feel secure even on trickier terrain. Credit: Justin Simoni
The Osprey Exos Pro 55 with a suggested load limit of 30 lbs 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 your body's shape while also providing a sprung, hammock-like surface to improve airflow. Zpacks suggests a max of 40 lbs as the Arc Haul Ultra's load limit.
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 with a suggested load limit of 35 lbs 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 sufficient support and rigidity for carrying 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. Unlike the other two, The Cutaway is a frameless pack, so overall comfort depends entirely 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 foam 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 your back's curvature, or you can remove it completely. Despite all of the other features, it's interesting that 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 58L is another standout pack for 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.
The Durston Kakwa 55, with its suggested load limit of 45 lbs, delighted us in its latest revision. Offering more hip belt size options to help dial in the fit and a hip belt that wraps all the way around, providing much better lumbar support and overall structure than ever before.
The hip belt has been redesigned on the Kakwa 55, becoming more supportive, more comfortable, and even more durable. Credit: Justin Simoni
Ease of Use
Good design is simple, functional, and often obvious, and we've found that the best ultralight packs are also the easiest to use. To that end, we tested all the features on each pack and noted when the design worked well and when we thought a feature needed a little work. For the most part, ultralight packs are simpler overall, shedding weight and complexity, and the very best integrate a thoughtful design that works well within these constraints.
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, including an impressive number of organizational pockets, for only a small weight penalty. If you're transitioning to the ultralight world from a more conventional backpack, this pack makes the transition utterly painless. Its design closely mirrors some of the manufacturer's conventional packs, just in a more lightweight form.
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 extra side pocket on the Mariposa is a welcome feature when we want to store just one more item on the outside.
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 many design cues from its more conventional cousin, the REI Co-op Flash 55, including its particularly deep side pockets and back padding.
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 a correlative approach, borrowing some of the best features from a spectrum of standout UL packs and assembling them into an all-star pack. We loved the easy-to-access side pockets, bottom stash pocket, and, of course, its stealthy, burly 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 in one of the side pockets, which allows us to securely store very important items, like keys, cards, and medication. Most of the remaining pack features are simple and easy to use, letting you focus on stamping out the miles ahead of you.
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 side pocket.
The Pa'lante V2 includes a built-in emergency whistle on its sternum strap.
Weight-to-Volume Ratio
We use weight-to-volume ratios to equalize packs of different sizes, so we can compare their base weight directly. We start by weighing the pack, then we relate it to the advertised volume, which usually includes both the internal capacity of the main compartment and the volume of any external pockets.
To verify the manufacturer's claims, we also measure the volume of the internal compartment and each exterior pocket. By and large, most pack makers are honest with the volume numbers that they list under a pack's specs. However, pack capacity, in liters, is sometimes different from the number used in the product name, which can cause confusion for consumers. It's also important to understand how the total advertised volume is partitioned between internal and external capacity.
We've noticed that, by and large, higher-capacity packs have a better weight-to-volume ratio, as it's usually “cheap” weight-wise to add volume to an already well-designed pack. If you're trying to squeeze every last gram off your pack list, go with a smaller volume pack. But if you're slowly transitioning from a more conventional kit to an ultralight setup – one piece of gear at a time – then consider a larger-volume pack.
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 into a giant graduated cylinder to measure the volume of ping-pong balls. The larger-diameter ping pong balls may not be as accurate as the standardized test, but we've found this test to be a worthy means of verifying manufacturers' claims. The ping-pong ball test is especially useful for comparing products from different manufacturers, as everyone seems to measure their packs differently – some use ASTM-standard 20mm balls, while others fill their backpacks with dried beans! We've run this test for years, and we're confident our measurement system is precise to within ±3 liters.
For external pockets, we'll use a variety of common items to get a feel of their carrying capacity. Often, external pockets are open-ended, so the exact volume is difficult to report, since what constitutes “full” is somewhat subjective. For center and side pockets, we normally use Smartwater bottles; for hip belt pockets, we use Clif Bars.
We use Smartwater bottles for the external side, center, and bottom pockets, and Clif Bars for the hip belt pockets, to give you a visual sense of the carrying capacity of these pockets.
But these numbers only help tell a part of the story. We also consider what each pack's total weight offers you when cross-referencing it with other important metrics, such as durability. You can carry your entire thru-hiking kit in a few large shopping bags, which would weigh less than another pack in our lineup, but we doubt you'd get too far up the trail. All the packs in the ultralight category fared extremely well in terms of weight-to-volume ratios, but there are certainly 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 often comes up when we look at packs with excellent weight-to-volume ratios, as these materials are incredibly durable yet comparatively lightweight. They're also very water-resistant, which means you may consider 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. We measured the internal capacity at 35 liters, and with a giant center mesh pocket, the pack weighs an incredible 0.44 oz/L. But the Arc Haul Ultra isn't alone – the Ultra 200X Durston Kakwa 55 also comes in at a very respectable 0.44 oz/L. Not to be outdone, the Ultra 200X Bonfus Framus 58L was measured with 55 liters of internal volume and a 0.46 oz/L weight-to-volume ratio. It's only slightly heavier than the Arc Haul Ultra and Kakwa 55 due to the taped seams. The more abrasion-resistant Ultra 400X bodies on the Ultralight Adventure Equipment Ultra Circuit and Black Diamond Beta Light 45 weigh 0.53 oz/L and 0.70 oz/L, respectively.
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. Many less expensive packs also use Ultra-high-molecular-weight polyethylene (UHMWPE) gridstop nylon, a higher-performing fabric than classic nylon. If you're looking to save a little weight and money on your next ultralight pack purchase, the 18.6-ounce Pa'lante V2 is made with strong, lightweight, and cost-effective 210D UHMWPE Nylon Gridstop. This pack and material boast a 0.5 ounces per liter weight-to-volume ratio (and that's only counting the pack's internal capacity, which is only what the manufacturer advertises this pack as having, capacity-wise). Side, center, and a bottom stash pocket will carry even more of your 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, particularly because the 21-ounce pack weighs significantly less than most other 40-liter packs in our lineup. This is a highly customizable pack, and we opted for the default Venom Gridstop ECO UHMWPE 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 determines how well an ultralight backpack fits your body and which sizing options are available at checkout. Adjustability also covers how well you can dynamically modify the pack's carrying characteristics as your load changes throughout your trip. Can you load up your backpack to the gills on day zero, knowing you won't see another town for a week? Finally, we're considering versatility: can the same pack be reasonably used across the country and for a weekend overnighter?
Ultralight backpacks once had a sour reputation for 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 and to offer a wider range of sizes, producing packs that are more accessible and comfortable for more people.
The adjustable hip belt on the Crown3 60 is one of its best features, allowing you to experiment with different lengths saving you from being stuck with a size that doesn't quite work for you. 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 lets you swap lengths and adjust the width and angle at which the straps attach to the pack.
Nashville Pack offers an impressive list of options for customizing The Cutaway before it even ships to you. Choose the pack's torso length and the perfect shoulder strap length to suit your 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 or narrow shoulders, and you can even 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 better suited to shorter trips, and grow with the pack as your ultralight backpacking experience matures. The Gossamer Gear Mariposa and Gossamer Gear Gorilla both scored highly for adjustability, offering an incredible amount of modularity in their similar designs, allowing 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.
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 belts, internal stays, and compression straps for very fast, 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 remove parts for a lighter load at the expense of carrying capacity and comfort.
Other Notable Ultralight Backpacks
These days, hikers are spoiled for choice in ultralight backpacks. Here are a few packs that we've tested previously and are still available, but which didn't quite make the cut for our current lineup:
Hyperlite Mountain Gear Porter 55 — This pack can be augmented for different light-and-fast missions by adding and removing modular accessories, thanks to a generous amount of daisy chains on the pack's exterior. But for dedicated ultralight backpacking, the lack of built-in center and side pockets, which are all but standard on most other ultralight backpacks, makes this pack less useful than some other options.
Hyperlite Mountain Gear Southwest 55 – This is a popular pack among thru-hikers, especially on the PCT and CDT, and for very good reason. Its weight-to-volume ratio is excellent, and unlike the Porter 55, it offers large exterior pockets. However, it's simply not as comfortable as the Hyperlite Unbound 40, which has an internal frame stay that adds necessary support.
Ultralight Adventure Equipment Ohm 2.0 — The Ohm is an excellent pack for just about everyone. However, the total weight is on the high side, especially considering the manufacturer's specified carry limit of 30 pounds.
Ultralight Adventure Equipment Circuit 68 — The Circuit 68 is another excellent option from ULA. However, now that the Ultra Circuit features Ultra 200X as the pack material, the Robic Nylon on the similarly sized Circuit 68 feels relatively heavy and a bit dated.
Ultralight Adventure Equipment CDT - The CDT is a no-nonsense ultrapack that can be customized before purchase. It makes for a great starter pack, especially considering the price and durability. However, your money may be better spent on the Ultra Circuit as a long-term investment.
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 from similarly sized packs. Unfortunately, the low weight is achieved by stripping features down to the bare minimum, making it much less comfortable than more modern packs.
Granite Gear Virga3 55 - This pack offers some intriguing features, including torso length/shoulder strap, and hip belt length adjustability. But at the end of the day, we think there are better introductory packs to choose from, including Granite Gear's own Crown3 60.
Mountainsmith Zerk 40 - With an impressive array of pockets, especially on the shoulder straps, the Zerk keeps things well organized and close at hand. While it's a compelling fastpack, it struggles to compete with lighter-weight options that offer greater internal carrying capacity.
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 weight trips.
Where will your ultralight backpack take you? Credit: Justin Simoni
Conclusion
An ultralight backpack becomes the cornerstone of your entire gear selection for your trip, simply because you'll need to carry everything else in it. Picking the perfect ultralight backpack can seem daunting, but we hope that with the guidance and information above, you can choose a pack that meets your needs and lasts for years of adventure. As you build out your ultralight kit, check out our other reviews of ultralight gear for more ways to shave a few ounces (or pounds) from your pack.
