Backpacking Pack Materials: A Deep Dive
Everything you need to know about the fabrics featured in this flagship gear category.
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There may not be another corner of the backpacking gear world progressing as quickly as pack fabrics. Over the past five years alone, we’ve seen a wave of new materials and technologies enter the scene, reshaping how manufacturers—and consumers—think about pack weight, durability, and weather resistance. Between these cutting-edge fabrics and traditional materials that have been used for decades, there’s a lot to sort through in this seemingly niche subject. In this guide, we’ll cover the major backpacking pack materials, so you can better understand your options and the construction that might make the most sense for your next pack.
A Quick Primer on Denier
Before we dive into different types of pack materials, let’s go over one of the most important fabric specs you’ll encounter. Denier, or “D,” measures a fabric’s thickness and, by extension, provides a rough idea of its strength. In technical terms, denier refers to the weight in grams of a single strand of textile measuring 9,000 meters long. That might sound pretty obtuse, but the simple takeaway when it comes to backpack design is straightforward: Given two packs made from the same material, such as nylon, the fabric with the higher denier rating will be thicker and more durable than a lower-denier one.
Just as the fabrics used in modern backpack design cover a wide variety, so do the deniers you’ll commonly see in the category. On the lighter end of the spectrum—usually models that prioritize weight savings and cater to the thru-hiker community—you’ll see packs built with materials as thin as 100D, such as the nylon Gossamer Gear Mariposa 60. More rugged designs, like the Gregory Baltoro 75, are reinforced with ultra-thick 630D fabric (nylon again, in that case). It’s also common for packs to supplement high-wear areas like the base with thicker fabrics than the majority of the body is made with. The Mariposa, for instance, has 210D nylon on its bottom and hipbelt.
That said, prioritizing durability in a pack isn’t as simple as picking a model with the highest denier number and calling it a day. Different fabrics have different inherent strengths, and so a pack made with a relatively stronger material like Ultra, for example, is significantly more durable than a nylon pack with fabric that has the same denier rating. The way a fabric is woven (if it has a ripstop grid, etc.) and if it has any surface treatments (a PU covering, for example) also play a role in overall toughness. And some materials, such as Dyneema Composite Fabric and some other ultra-high-molecular-weight polyethylene (UHMWPE) blends, aren’t measured in denier at all, despite being extremely strong.
The point is, denier is a helpful starting point when evaluating pack durability, but it’s only one piece of the puzzle. Understanding the qualities of the fabric itself and how it’s used by designers will give you a much clearer picture of how hardy a pack really is.
Nylon: The Longtime Standard
Nylon is by far the most common fabric used in backpacking packs and has been a mainstay in the category for decades. The reason is straightforward: It offers a decently high strength-to-weight ratio (especially compared to its closest rival, polyester, which can be found in some models like the Osprey Rook/Ren, but is much more rare), and it’s relatively inexpensive to produce. As a result, nylon shows up in nearly every corner of the pack market. Everything from the top pick in our Best Backpacking Backpacks Guide, the Osprey Atmos AG LT 65, to budget-friendly options like the REI Co-op Trailmade 60 and ultralight favorites such as the ULA Circuit, all feature nylon construction.
Compared to newer UHMWPE-based pack materials, such as Dyneema and Ultra, nylon will save you some cash when you’re pack shopping. For example, minimalist packs that feature those first two fabrics, such as the Hyperlite Mountain Gear Southwest 55 or the Zpacks Arc Haul UltraEXP, often sit around $400. Competing nylon models, such as the ULA Circuit or the Atmos AG LT, on the other hand, are closer to $300. Nylon also doesn’t quite match the strength-to-weight ratio of UHMWPE fabrics, but that doesn’t mean it’s fragile. Case in point: One of our testers used the nylon Gossamer Gear Mariposa on a thru-hike of the Continental Divide Trail, while components like the mesh pockets, stitching, and buckles showed some wear over the course of the 3,000-mile journey, the fabric itself held up impressively well.
Nylon’s main limitation when stacked up against more expensive materials is weight. You’ll need a thicker (and thus heavier) version of the fabric to achieve performance comparable to a UHMWPE material of similar durability, which, of course, affects overall pack weight. The Mariposa 60 is the lightest framed nylon backpack we’ve reviewed, checking in at 2 pounds, 2.2 ounces. But the similarly designed Hyperlite Southwest 55 and Zpacks Arc Haul UltraEXP 60 both come in well under two pounds (1 lb. 14.8 oz. and 1 lb. 7 oz., respectively), due in large part to the Dyneema and Ultra composite fabrics they feature, respectively.
Additionally, nylon isn’t waterproof, a user-friendly bonus granted by UHMWPE materials. It won’t soak through immediately if you’re caught in the rain, but during prolonged exposure, it can absorb water and soak through, so you should carry a pack cover in wet conditions. Still, for the vast majority of backpackers, nylon remains the go-to fabric, and it’s unlikely to disappear from the market anytime soon.
Nylon Variables
Now you know the differences between nylon and other materials, but there’s also a fair amount of nuance within the nylon landscape itself. Not all of it is created equal, and two nylon pack fabrics that look similar on paper can offer drastically different amounts of durability and performance. Here are the details to look for in nylon’s fine print.
Coatings and Treatments
Many pack manufacturers apply coatings or treatments to nylon fabrics to improve water resistance and durability. Two of the most common are durable water-repellent (DWR) finishes and polyurethane (PU) coatings, both of which help moisture bead up and roll off the pack's surface for a time rather than immediately soaking through and reaching your gear. PU also grants a durability boost by providing another thin layer atop the fabric itself.
As we mentioned before, a DWR or PU coating is no substitute for true waterproofing, and even treated nylon will soak through in a downpour. However, they do a decent job of combating moisture for a short time or in light rain. We used the DWR-treated REI Co-op Flash 55 on a drizzly trip through the Enchantments in Washington State, and it kept our gear dry. That said, these treatments have their limits. For trips where wet weather is likely, though, it’s a good idea to use a pack liner or rain cover to keep your gear protected.
Weaves and Fiber Types
A nylon fabric’s weave pattern can greatly improve its strength. The simplest construction, known as plain weave, is not particularly rugged or abrasion-resistant. Because backpacks regularly scrape against rocks, brush past twigs, and get dropped onto uneven ground, plain weaves are relatively uncommon in this gear category.
Ripstop nylon, however, is a much more common and effective option. This construction combines a thin nylon base fabric with thicker reinforcing yarns woven in a box pattern throughout the material. The thicker strands help stop small punctures from spreading into larger tears (hence the name). Ripstop is widely used for its improved durability with a minimal weight penalty, and you can find it in everything from budget-friendly packs like the REI Co-op Trailmade to well-regarded premium models like the Circuit.
In addition to weave patterns, many packs use high-tenacity fibers engineered to be stronger than traditional nylon. It’s slightly more expensive, but it has greater tear resistance to help keep snags and rips at bay. A pack built with these enhanced materials will be tougher than one with the same denier rating made from standard nylon. Robic, a common brand name for high-tenacity nylon, is used in the Mariposa and played a big role in keeping that pack’s fabrics intact throughout our tester’s CDT thru-hike.
Dyneema: The Revolutionary
It’s not an exaggeration to say that Dyneema Composite Fabric (DCF) transformed the backpacking gear landscape. Originally developed for competitive sailing, the material quickly gained attention for its fantastic strength-to-weight ratio and inherent waterproofing—traits that translated perfectly to ultralight backpacking gear.
Technically, “Dyneema” is a brand name within a class of materials known as ultra-high-molecular-weight polyethylene, or UHMWPE. DCF, formerly known as Cuben Fiber, is a specific fabric that’s made by sandwiching non-woven Dyneema fibers between two thin sheets of Mylar (polyester) film. The result is an exceptionally strong textile with a very low weight—DCF’s tensile strength is often claimed to be around 15 times stronger than steel on a pound-for-pound basis, and it’s much lighter than nylon.
Add in the fact that the Mylar laminate also makes DCF waterproof, and you have a material that seems tailor-made for featherweight packs that can take a beating and hold up, no matter the weather. Those qualities attracted ultralight gear stalwarts like Hyperlite Mountain Gear and Zpacks, which began to use DCF in their packs in the late 2000s. Over the next couple of decades, the material became widespread in backpacks designed for thru-hikers and other minimalists.
Recently, however, DCF has lost some of its shine. It suffers from some noticeable tradeoffs, the most obvious of which is cost. The material is significantly more expensive to produce than nylon, which translates to higher pack prices. And while its tensile strength is impressive, its non-woven construction makes it more vulnerable to abrasion and pinhole damage. (We’ve seen this firsthand after setting DCF packs down on rocks during trail breaks.) Over time, those small punctures can compromise both the fabric’s durability and its waterproofing.
Those drawbacks have largely driven the original DCF out of the backpacking pack world (although it’s still thriving in the backpacking tent space). None of the models in our backpack gear guide currently feature it, even if it comprised their original construction. Since the early 2020s, virtually all ultralight pack manufacturers, including Zpacks and Hyperlite, have phased out DCF in favor of better-performing UHMWPE textiles—let’s get into those now.
Ultra: The Student Becomes the Master
In recent years, Ultra has surged in popularity among ultralight backpack designers and their customers, quickly becoming their fabric of choice. Brands that once relied heavily on DCF, such as Zpacks and Mountain Laurel Designs, have increasingly shifted to Ultra-based materials for their latest packs.
Produced by Challenge Outdoor, Ultra is another UHMWPE-based fabric that first cut its teeth in the sailing world before expanding into performance outdoor gear. In backpack design, the most common fabrics come from Challenge’s UltraWeave collection. This recipe combines a woven Ultra face fabric with high-tenacity polyester fibers, a cross-ply layer of Ultra arranged diagonally, and a waterproof film backing. The material is available up to 800D, though most packs use Ultra100X (100D) or Ultra200X (200D) to keep things nice and light.
Like DCF, all UltraWeave fabrics command a high price and are also waterproof thanks to their laminated film backing. But UltraWeave’s main selling point—and the reason many high-end cottage gear manufacturers have made the switch—is its higher durability. Its woven face fabric resists scrapes and punctures even better than DCF’s Mylar face, and the diagonally-arranged Ultra midlayer boosts multidirectional strength as well. For additional reinforcement, some packs, such as the Arc Haul UltraEPX, pair an UltraWeave base with an extra layer of Ecopak (Challenge’s recycled waterproof polyester fabric) for an even burlier build.
Aluula: The Up-and-Comer
Aluula is one of the newest fabric manufacturers in the backpack design landscape, and perhaps the most talked-about at the moment. Its Graflyte fabric is among the next generation of UHMWPE-based materials, and is quickly being adopted by packmakers across the industry. Cottage manufacturers like Nashville Packs and Durston, along with more established brands such as Arc’teryx, have incorporated it into their designs; most recently, Mountain Hardwear chose Aluula for the construction of its Alakazam series of packs.
What sets Aluula apart is its construction process. Instead of using adhesives to laminate layers together—as is the case with fabrics like DCF and UltraWeave—Aluula employs a proprietary bonding process that fuses its 100% woven UHMWPE face fabric directly to a waterproof film. The result is a two-layer design, rather than the three-layer arrangement used in other UHMWPE fabrics, which reduces weight even further and eliminates the risk of delamination caused by glue degradation over time.
The material is impressively light, even compared to its UHMWPE competition. Aluula doesn’t publish a denier rating for Graflyte, but the V-98 version of the fabric used in several packs, such as the Durston Wapta and the Nashville Packs Cutaway, weighs 2.9 ounces per square yard, compared to 3.1 ounces for 100D DWC and 3.3 ounces for Ultra100X. The Mountain Hardwear Alakazam features an even lighter variant, weighing just 2.3 ounces per square yard, which makes it one of the lightest UHMWPE-based pack materials currently available.
The main drawback to packs built with Aluula, unsurprisingly, is price. The Mountain Hardwear Alakazam, for example, pushes close to $600—that’s even more eye-watering than notoriously expensive models from Hyperlite and other ultralight pack brands (for more, read our Alakazam review). Still, the technology is young, and we’re curious to see how it develops as more brands experiment with the material. If early momentum is any indication, it’s only a matter of time before Aluula becomes a major player in the ultralight backpacking market.
Don’t Count Dyneema Out
To counter DCF's weaknesses as alternatives like Ultra and Aluula come to the fore, Dyneema has developed its own line of woven composites. Dyneema Composite Hybrid (DCH) is now found in many of Hyperlite’s packs, including its Unbound series, and adds a woven face layer, typically polyester or nylon, on top of the Dyneema lattice pattern. The result is a hybrid material that combines Dyneema’s tensile strength with the improved abrasion resistance of a woven outer fabric, rather than the non-woven polyester sheets used by DCF.
But the brand’s newest and most notable product is known as Dyneema Woven Composite (DWC), which debuted on Hyperlite’s core backpacking lineup—the Southwest, Junction, and Windrider—in 2025. Like DCH, this material also features a woven face fabric, but this time made with Dyneema fibers. That major yarn upgrade adds even more strength and abrasion resistance while maintaining the low weight that Dyneema is known for.
But how does it stack up to UltraWeave, its closest competitor? Weight-wise, they’re almost identical. The 200D DWC and Ultra200X both weigh 3.9 ounces per square yard, and the 100D versions are also closely matched (DWC is 0.2 oz./sq. yd. lighter). Direct durability comparisons are trickier; each brand reports tear strength using different testing methods, and DWC is so new that we’ve had limited real-world testing.
It will be interesting to see how DWC affects the backpacking fabrics landscape, but we’re not convinced yet that it’ll challenge UltraWeave’s top spot—it’s currently exclusive to long-time Dyneema loyalist Hyperlite, while UltraWeave is far more widely available. Unless DWC can prove its superiority and expand its roster, it will likely remain in the shadow of UltraWeave’s dominance. For an even deeper analysis, see our article: Dyneema (DCF) in Backpacking Gear.
Gridstop: Durability on a Budget
Even with advancements in durability and performance, the Achilles’ heel of ultralight pack materials remains the same: cost. This is where gridstop slots in, offering backpackers many of the benefits of UHMWPE fabrics without the top-dollar price tag.
Gridstop is a type of reinforced ripstop fabric that starts with a woven base fabric (typically nylon) and integrates stronger UHMWPE yarn in a grid pattern throughout the material to boost durability. Depending on the manufacturer, gridstop fabrics may be marketed under different names. Challenge Outdoor’s version is called UltraGrid, while versions that incorporate Dyneema fibers will typically highlight that in the branding.
To improve water resistance, gridstop fabrics are typically coated with PU, though they aren’t fully waterproof. They also tend to be slightly heavier than premium Dyneema or Ultra fabrics. For example, 210D UltraGrid weighs 4.3 ounces per square yard, compared to 3.9 ounces per square yard for 200D Ultra200X. Durability lags slightly behind UltraWeave and DWC, too, though gridstop is still tough enough to handle burly backcountry use.
But the real winner here is your wallet. Take the Durston Kakwa 55: The UltraGrid version costs $199, while the UltraWeave 200X version goes for $279. Other cottage ultralight brands—including Nashville Packs and Pa’lante—also offer gridstop options on some of their pack models to help ease the cost burden. And not for nothing, gridstop comes in lots of colors, far beyond the grayscale palette of most UHMWPE composite fabrics. Ultimately, if you want better performance than standard nylon without paying a premium for Ultra or Dyneema, gridstop offers a compelling alternative.
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