The Zpacks Arc Haul 62L Backpack is an ultralight, ventilated, and adjustable-length backpack made with conventional HDPE gridstop fabric instead of the Dyneema DCF used in the company’s other products. Weighing 22.5 oz, it’s set up like most ultralight-style backpacks with a roll-top closure, front mesh pocket, and side water bottle pockets. But what sets this pack apart from other ultralight backpacks, besides its incredible light weight, is a user-adjustable frame that lets you set the depth of the ventilation curvature and torso length based on your preferences and load characteristics. Zpack’s lower capacity Arc Blast 55L Backpack shares the same frame which has been refined and perfected over the course of many years.
Specs at a Glance
- Weight: 22.5 oz
- Gender: Unisex, but very female friendly (see below)
- Pockets: 3 (hip belt pockets are available as an add-on purchase @ $50/pair)
- Hydration compatible: Yes
- Ventilated: Yes
- Volume: 62L (49L main body, 2.5L each side pocket, 8L center pocket)
- Fabric: HDPE Gridstop (body), lightweight mesh (front pocket), spacer mesh (shoulder strap/hip belt padding)
- Max Recommended Load: 40 lbs (we rate it closer to 25-30 lbs)
Backpack Storage and Organization
The Zpacks Arc Haul 62L is shaped like most ultralight-style backpacks with a large main compartment, front mesh pocket, and side water bottle pockets. The main compartment closes with roll-top and has a narrow velcro-stiffener on top. A single strap loops over the roll-top to secure it. There is a central hydration port inside the pack if you want to use a reservoir and hose, and a small webbing loop to hang it from, but no separate hydration pocket. The interior is heavily seam-taped for waterproofness and complements the interior PU coating applied to the pack’s HDPE gridstop fabric, making the backpack highly water-resistant, although we’d still recommend lining it with a plastic bag or pack liner.
The size and shape of the main compartment is significantly altered when the pack’s frame is arched to create a ventilation cavity. This is true of most ventilated backpacks. When the back of the pack behind your torso curves inward, it loses width and items can be harder to pack or unpack, since you have to reach around the resulting bulge. Packing your gear around a full-sized bear canister can also be challenging in these circumstances. This is a common characteristic typical of backpacks with ventilated frames.
The front mesh pocket is made with a lightweight mesh fabric and has an elastic top, but can’t be tensioned closed on top. Its effective capacity is also limited by the amount of gear packed into the main compartment and the degree of curvature imposed on the frame which can reduce the pockets effective capacity. The mesh fabric is also comparatively lightweight and less robust than the mesh that other ultralight and mainstream pack manufacturers are currently using to improve durability.
The side water bottle pockets are made with the same HDPE gridstop as the body, so they’re much tougher than the mesh on the front stretch pocket. They’re large enough to hold two SmartWater bottles, but you can only get one 1L Nalgene into them. They also have non-adjustable elastic running through the top to keep bottles from falling out. While they’re reachable when the pack is worn, the elastic can makes it a little challenging to get a bottle back in, if you’re carrying anything else in the pockets. That’s not a showstopper, just an observation about the structure and capacity limitations of the side pockets.
The Arc Haul 62L does not come with hip belt pockets and they’re an add-on purchase at $50/pair. They are attached with an elastic band and cord locks to the hip belt, which has daisy chains sewn on its exterior. The pockets are available in HDPE gridstop or Dyneema DCF for the same cost.
Backpack Frame and Suspension
The Zpacks Arc Haul 62L has a ventilated, trampoline style frame that lets air flow behind your back so you stay cooler and perspiration dries faster. This can make backpacking much more pleasant in hot and humid conditions. Zpacks is unique amongst UL pack manufacturers in offering this type of frame. While other manufacturers, like Osprey, Gregory, and Deuter offer a similar capability, theirs is much more tightly integrated and encapsulated than the Arc Haul frame which is completely visible, externalized, and adjustable by the end-user. While this gives the Arc Haul a somewhat Frankenstein-like appearance with all kinds of straps and rods, it’s designed this way on purpose to keep the pack weight as low as possible. The closest comparable ventilated backpacks made by Osprey or Gregory, weigh 50-100% as much as the Arc Haul but do not have adjustable torso lengths.
The Arc Haul frame is quite simple. There are three horizontal crossbars, positioned along the top, middle, and base of the packbag. Two flexible carbon fiber rods are attached to the corners of the top and bottom bars and a mesh back panel is connected to them with webbing straps. When tensioned, the webbing straps cause the carbon fiber rods to bend and form an arc, with the mesh suspended over it. The middle crossbar keeps the pack bag from collapsing backward and filling the cavity created by the arc. The Arc Haul’s shoulder straps and load lifters are connected to the top crossbar, while the hip belt is attached to the bottom crossbar. It’s as simple as that.
When tensioning the arc, Zpacks recommends making it 2.5 inches deep. You can make it deeper or shallower based on your personal preferences. For example, you could eliminate the arc completely if you just wanted a very lightweight backpack without any ventilation or you need to scramble up a cliff face and want the pack’s center of gravity as close to your back as possible.
Despite the simplicity of the frame, dialing in a really good fit can require a fair amount of experimentation with different loads and arc depths. For example, whenever you create an arc, the distance between the shoulder straps and the hip belt (torso length) changes as well. Zpacks has a good pack fitting video that explains the basics (see Adjustment and Fit tab), but it can be a little time consuming to get a balanced and accurate fit that you can reproduce in the field if warranted.
The Arc Haul frame was an adjustable length torso capability, which lets you raise or lower the height of the shoulder straps up to 4″. This can make a huge difference in the fit of the Arc Haul 62L and its load-to-hip transfer but is best done as a refinement after you’ve adjusted the arc to its desired depth.
The torso adjustment mechanism is also quite simple. The shoulder straps are connected to two vertical interior webbing straps that are connected to the top crossbar and at points just above the middle crossbar. If you push the top of the shoulder strap down to lower it, you shorten the distance between the hip belt and the top of the strap, thereby shortening the pack’s torso length. If you raise the strap, you lengthen the torso length. It’s important that you keep two shoulder strap heights the same, so one shoulder doesn’t do more work than the other. The actual amount of torso length adjustment used is best done by feel while wearing a loaded backpack and after the arc depth has been set. See the Zpack’s pack fitting video on the Adjustment and Fit tab for more details.
The Zpacks uses S-shaped shoulder straps on their packs, which are better for men and women because they wrap around the pecs rather than smash them flat, like the J-shaped straps found on other unisex backpacks. The straps are not sewn directly to the crossbars or pack bag but attached by a webbing strap that permits the top of the pad to conform to the shape of your shoulders for a more personalized fit. The shoulder straps are lightly padded and covered with wicking spacer mesh. The exteriors have daisy chains sewn to them that makes it possible to attach accessory pockets or reposition the sternum strap.
The Arc Haul hipbelt is available in a variety of lengths so you can get a good fit. It’s also replaceable, which is nice if you gain or lose weight and want to change size. The hipbelt also has exterior daisy chains suitable for attaching accessory pockets although none are included with the base backpack.
The hipbelt is female-friendly because it has upper and lower webbing straps that can be used to create a differential fit and accommodate curvy female hips or flattish male ones. The hipbelt is lightly padded, which you’d expect on an ultralight backpack used to carry lighter loads. It does not have a lumbar pad, although one is available as an accessory add-on.
While the Arc Haul 62L has a frame, its primary function is ventilation and doesn’t substantially increase the load-carrying capacity of the pack. I’ve carried multi-day loads with the Arc Haul 62 and find that the maximum comfortable load including gear, food, and water is about 25-30 pounds. Zpacks rates it much higher at 40 lbs, but that hasn’t been my experience using it.
Backpack Compression and External Attachment System
The Arc Haul 62L is fairly light on compression capabilities and attachment capabilities but provides room for you to expand on them if you wish to customize them.
In addition to roll-top, which provides top-down compression, the Arc Haul has a static cord-based side compression system that’s tensioned with a cord lock and sleeping pad attachment cords, which are a nice feature, not found on most UL backpacks. The same cord system can also be used or modified to carry an ice ax or even trekking poles, using the side compression cords to secure the shafts.
|Make / Model||Weight||Ventilated||Adjustable Length||Price|
|HMG 3400 Junction (55L)||32 oz||No||No||$345|
|Granite Gear Crown2 60L||36.7oz||No||No||$200|
|Gregory Optic 58L||45.3 oz||Yes||No||$210|
|Gossamer Gear Mariposa 60L||32.7 oz||No||No||$225|
|MLD Exodus 58L||18 oz||No||No||$235|
|Osprey Exos 58L||43 oz||Yes||No||$220|
|Osprey Levity 60L||31.2 oz||Yes||No||$270|
|SWD Long Haul 50L||26.5 oz||No||No||$265|
|ULA CDT (54L)||24 oz||No||No||$145|
|ULA Ohm 2.0 (63L)||34.5 oz||No||No||$225|
|Zpacks Arc Blast 55L||20.1 oz||Yes||Yes||$325|
|Zpacks Arc Haul 62L||22.5 oz||Yes||Yes||$299|
The Zpacks Arc Haul 62L is an ultralight ventilated and adjustable-length backpack designed for multi-day backpacking trips and thru-hiking. Weighing just 22.5 oz it’s significantly lighter weight than comparable backpacks even though it has a much more sophisticated and adjustable length frame system. While there is a higher initial learning curve to adjusting and fitting the Arc Haul than more conventional ventilated backpacks, once you’ve dialed in the fit, the backpack carries like a dream, comfortably transferring loads to the hipbelt while keeping your back cool and dry.
If you’re trying to significantly reduce the weight of your backpacking gear and want a ventilated backpack, I’d recommend getting the Zpacks Arc Haul 62L or the Zpacks Arc Blast 55L, which is lower volume but quite similar in design and made with Dyneema DCF.
Disclosure: Zpacks provided the author with a backpack for this review.Editor's note: Help support this site by making your next gear purchase through one of the links above. Click a link, buy what you need, and the seller will contribute a portion of the purchase price to support SectionHiker's unsponsored gear reviews, articles, and hiking guides.
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