REI Co-op Magma 15 Sleeping Bag Review
REI Co-op brings premium sleeping bag design to a wider audience with the Magma 15 ($399), pairing 850-fill down with a price that undercuts many similarly warm competitors. It’s not a feature-heavy bag, and it's too heavy to qualify as ultralight, but its wide range of size options—the most we’ve seen from a major brand—helps it stand out as a strong value pick for backpackers who want real warmth, a dialed fit, and straightforward performance without stretching their budget.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Temp Rating
21/9°F (ISO Comfort/Limit)
Weight
2 lb. 3.6 oz.
Fill
1 lb. 7.3 oz. of 850-fill down
Shell
15D nylon
Shoulder/Hip Girth
62.5/54 in.
Packed Volume
8L
Other Temps
30F
Pros
Cons
REI Co-op Magma 15
For this season's top models, see our guide to the Best Backpacking Sleeping Bags.
With a 21-degree Fahrenheit Comfort Rating and a 9-degree Fahrenheit Lower Limit Rating, the REI Co-op Magma 15 ranks among the warmest ISO-rated backpacking bags in the “15-degree” class. Other similarly rated options, like the premium-priced $549 Sea to Summit Spark 15 (29/15°F) and $660 Western Mountaineering UltraLite (25/14°F), along with my Nemo Disco 15 (26/17°F), aren't built to push quite as low.
The primary reason for the Magma 15’s warmth is its fill weight, or the amount of down inside the bag. To be specific, it packs a substantial 1 pound 7.3 ounces of 850-fill down. For comparison, the aforementioned Spark uses just 1 pound, 0.9 ounces of the same fill power down, while the UltraLite has even less. Weight is the obvious trade-off: The medium size I tested weighs 2 pounds 3.6 ounces, which puts the Magma outside true ultralight territory. Bags like the Spark (1 lb. 9.7 oz.) and UltraLite (1 lb. 13 oz.) are better options for those looking to shave ounces, even though they have less impressive warmth ratings.
In the field, I used the REI Co-op Magma 15 on a low-30s night paired with my 4.4 R-value Exped MegaMat Ultra while backpacking near an alpine lake, and stayed toasty all night. The cinchable hood and mummy silhouette help seal in heat, and overall, the Magma’s insulating power does a lot to justify its heavier build. For value-minded backpackers looking to maximize warmth while minimizing weight, the Magma is hard to beat.
It’s worth noting that REI also makes a 30-degree version of the Magma, which is just about as popular as the 15-degree model. In terms of warmth, the Magma 30 has a 34-degree Comfort Rating and a 21-degree Lower Limit, so it runs about 12 to 13 degrees colder. But the weight savings are significant—the bag weighs just 1 pound 8.4 ounces, or over 11 ounces less. For summer backpacking and those who stick to lower elevations, the Magma 30 is a nice option and will save you $50. But for the alpine and the shoulder seasons, you’ll likely want to stick with the 15.
The Magma 15 uses a traditional mummy silhouette, a shape that can sometimes feel restrictive, but that wasn’t my experience here. It felt noticeably roomier than expected—I tend to toss and turn at night, and I was able to shift positions without feeling overly constrained or wrestling with the bag. The smooth ripstop nylon lining helped: It’s soft and quiet, making it easy to move around inside the bag without the fabric bunching or twisting as I rolled over.
The medium-size Magma I tested measures 62.5 inches at the shoulders and 54 inches at the hips, before tapering more aggressively through the knees. That tapered shape helps with thermal efficiency, but it does limit how far you can sprawl compared to more comfort-focused backpacking sleeping bags. For reference, my Nemo Disco takes a different approach with its hourglass silhouette, featuring a 62-inch shoulder girth, along with a generous 61-inch circumference at the knees, narrowing to 57 inches at the hips. That layout is more accommodating for side sleepers or anyone who moves around a lot like me, though it comes with a weight penalty (the Disco is 2 lbs. 11 oz. for a size regular, or more than 7 ounces heavier than the Magma).
Along with its mummy shape, the REI Magma 15 has a cinchable hood and an insulated yoke to help seal in warmth. A 3D footbox also adds a bit of space for natural foot position, but there aren’t many extras beyond that. That said, with an impressive nine different unisex sizes available, it’s easy to find a version that suits your body and sleeping preferences.
The REI Co-op Magma 15 keeps things minimal, focusing on core functionality rather than piling on extras. It includes a cinchable hood and an insulated yoke around the neck and shoulders that works much like a draft collar, helping seal in heat without adding much bulk. There’s also a small internal stash pocket, which I used for a sleep mask and headlamp, and a few thoughtful design touches that improve day-to-day usability. The trapezoidal footbox gives your feet a bit more room, and the zipper runs up to and above the chest rather than off to the side, making it easier to zip the bag on and off. The zipper also sports an anti-snag strip to help prevent the fabric from catching.
Features-wise, the bag is noticeably simpler than the Nemo Disco 15 I’ve used, which adds side vents for temperature regulation, a pillow barn in the hood, and a large draft collar. That said, the Magma’s pared-down approach worked well for my needs. It’s significantly lighter than the Disco, and I found the Magma easier to pack down.
The Magma uses a recycled 15-denier ripstop nylon shell and liner, which isn’t especially burly, but it also doesn’t feel alarmingly thin. For comparison, my Disco uses a tougher 20-denier recycled polyester fabric with reinforced panels at the hood and footbox, while lighter-weight backpacking sleeping bags like the Sea to Summit Spark dip down to 10-denier fabrics to cut weight. In that context, the Magma feels appropriately balanced for its weight, even if it doesn’t stand out for durability.
During my backpacking adventures, nothing about the Magma’s construction raised red flags. The zipper, in particular, felt high quality—wide, smooth, and confidence-inspiring—and I didn’t worry about catching the fabric when opening or closing the bag. That said, because the Magma isn’t reinforced like my Disco, I do have some concerns about the durability of its hood and footbox, which tend to see the most wear and tear.
Still, I feel the Magma strikes a nice balance between weight and durability. It’s decently lightweight, and while it’s not the most durable sleeping bag around, that tradeoff works for me. I’m careful with my gear and regularly use delicate, ultralight items, so taking a bit of extra care with a bag like this feels reasonable given the warmth and value it delivers.
Like most down sleeping bags, the Magma offers some built-in moisture protection, but it still requires care in wet conditions. The shell features a durable water repellent (DWR) treatment that helps moisture bead up and slows saturation, though insulation performance will still drop if the bag gets soaked. This is an area where fully synthetic bags like the Marmot Trestles Elite Eco 20 have an advantage, as they continue to insulate when wet. That said, the weight of synthetic insulation is so high that we know almost nobody who brings them into the backcountry (the Tretles works best for short jaunts and as a crossover bag for car camping).
To help mitigate down’s typical weaknesses, the Magma uses water-resistant goose down, which adds a layer of protection against light moisture. That said, my Disco is even more water resistant, with waterproof-treated fabrics at the hood and footbox—areas that are most likely to brush against tent walls and collect condensation.
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Longevity
Choosing durable outdoor gear and keeping it in use for longer is one of the best ways to reduce environmental impact. Our proprietary longevity rating assesses factors like overall build quality, materials, fabric denier, component durability, and real-world performance. A green check indicates that we expect the product to be long-lasting relative to its peers, a yellow check mark indicates average longevity, and a red X indicates a product that may have a limited lifespan.
Responsible Down
The Responsible Down Standard (RDS), developed by Textile Exchange, is the leading certification for responsibly sourced down and uses third-party audits throughout the supply chain to verify animal welfare, responsible farming practices, and safe working conditions. Recycled down is another responsible choice that helps reduce demand for newly sourced down while keeping existing materials in circulation. A green check mark indicates a product uses responsibly sourced or recycled down, a yellow check mark indicates the brand sources responsible or recycled down for the majority of its products but does not specify it at the product level, and a red X indicates the product does not use responsibly sourced or recycled down.
PFAS-Free DWR
Durable water-repellent (DWR) finishes can contain PFAS (per- and polyfluoroalkyl substances). These highly persistent “forever chemicals” are used in outdoor gear for their strong resistance to water, oil, and heat, but are linked to environmental contamination and a range of health concerns. A green check mark indicates the product uses a PFAS-free DWR, while a red X means the DWR contains PFAS.
Recycled Materials
Recycled materials are prevalent in outdoor gear, with nylon, polyester, wool, and down among the most common, but the composition varies widely. A green check mark indicates the product is made with a substantial amount of recycled materials (100% recycled or the core fabric that makes up most of the product is recycled), a yellow check means it contains a moderate to small amount of recycled materials, while a red X means there are no recycled materials in the product.
Bluesign Approved
Bluesign Technologies, based in Switzerland, operates a third-party textile management system that ensures materials are manufactured to strict environmental, chemical, and worker safety standards. A green check mark indicates a product is either a Bluesign Product (contains at least 90% Bluesign-approved fabrics and 20-30% Bluesign-approved accessories) or features a significant amount of Bluesign-approved materials. A yellow check mark means it uses some Bluesign-approved materials but less than the aforementioned category, and a red X means there are no Bluesign-approved materials in the product.
Responsible Manufacturing
This criterion evaluates a brand’s commitment to fair wages, safe working conditions, and reducing environmental impact through certifications and programs like Fair Trade Certified, Fair Wear Foundation, Worldwide Responsible Accredited Production (WRAP), and the Fair Labor Association, while also recognizing brands that manufacture primarily in the U.S. or Europe under strict labor and environmental regulations. A green check mark indicates a brand meets our responsible manufacturing criteria, while a red X means it does not.
Recycled and/or Reduced Packaging
Packaging can add significant waste to outdoor gear purchases, so many brands work to reduce its impact by using recycled materials, incorporating Forest Stewardship Council-certified paper products, and minimizing plastic and paper use. A green check mark indicates a brand uses recycled or reduced materials across all of its packaging, a yellow check indicates moderate or limited use of recycled or reduced packaging, and a red X indicates the brand does not make either of these efforts.
Repair Services
Repair services extend the lifespan of outdoor gear and reduce overall consumption, though programs vary widely. Some brands offer comprehensive repairs for a range of issues, while others provide limited or no repair support. A green check mark indicates a robust repair program, a yellow check mark indicates limited repair services, and a red X indicates the brand does not offer repair services.
Resale and/or Recycling Services
Resale and recycling programs help keep outdoor gear in circulation longer and out of landfills, ranging from trade-in resale platforms that offer store credit to take-back initiatives that recycle products at the end of their usable life. A green check mark indicates a brand offers both resale and recycling programs, a yellow check mark indicates it offers one or the two, and a red X indicates it offers neither.
Carbon Footprint Tracking
This criterion evaluates whether a brand measures, reports, and works to reduce its greenhouse gas emissions using established frameworks such as the Higg Index, Greenhouse Gas Protocol, or The Change Climate Project. A green check mark indicates a brand publicly reports greenhouse gas emissions data, sets clearly defined reduction targets, and uses established tracking frameworks such as Higg or The Change Climate Project. A yellow check mark indicates the brand tracks emissions and outlines reduction goals but provides limited data, lacks science-based verification, or does not clearly report progress. A red X indicates the brand does not appear to track greenhouse gas emissions or provides so little information that its efforts cannot be verified.
Annual Impact Report
Annual impact reports provide transparency and accountability by outlining a brand’s sustainability efforts across areas such as material sourcing, greenhouse gas emissions, waste, water use, supply chains, and packaging. A green check mark indicates a brand publishes a detailed, brand-specific impact report that closely aligns with our sustainability criteria and leaves little room for ambiguity. A yellow check indicates a brand provides some relevant sustainability reporting but lacks detail in key areas or is covered only briefly within a parent company report. A red X indicates a brand does not regularly publish an impact report.
The REI Co-op Magma 15 I tested was a size medium, which fits backpackers up to 71 inches tall and has girths of 62.5 inches at the shoulders and 54 inches at the hips. I’m 5-foot-8, and the fit felt just right. Even with its traditional mummy silhouette, there was enough room to move around comfortably—I could lie on my back with one leg straight and the other bent at a 90-degree angle without stretching the fabric or feeling constrained. For a mummy bag, it feels surprisingly roomy.
One of the Magma’s biggest strengths is how many size options are available. There are nine unisex size variations to choose from, with short, medium, and long lengths offered in narrow, regular, and wide widths. On the smaller end, the short narrow fits folks up to 65 inches tall with a 54-inch shoulder girth and 45.5-inch hip girth. At the other extreme, the long, wide accommodates backpackers up to 77 inches tall with a generous 71-inch shoulder girth and 63.5-inch hip girth. With that big a range, it’s easy to dial in a fit that matches both your body size and how much room you prefer in a sleeping bag.
Nemo Riff 15 ($400): More Bells and Whistles
We’ve talked a lot about the uber-popular Nemo Disco in this review, but the Riff 15 is a more direct competitor. To sum it up, the Riff clearly prioritizes features, while the Magma takes a more stripped-down approach. Both bags include a cinchable hood, but the Riff swaps the Magma’s insulated yoke for an oversized draft collar and adds torso vents and a pillow barn in the hood (though it notably drops the stash pocket). The Riff also reinforces the head and foot with thicker, waterproof-treated fabrics to reduce wear and guard against moisture—something the Magma doesn’t offer.
In terms of fit, the Riff features an hourglass shape that widens at the knees, but its 60-inch shoulder girth is actually more restrictive than the Magma’s 62.5 inches, which undercuts its toss-and-turn-friendly design. It’s also heavier by more than three ounces and not as warm (28/17°F ISO Comfort/Limit). For feature lovers, the Riff makes sense, but for warmth, weight, and fit flexibility, the Magma is the better choice. For more, check out our review of the Riff 15.
Therm-a-Rest Parsec 20 ($470): Colder and More Expensive
Despite costing about $70 more, the Therm-a-Rest Parsec 20 isn’t as warm as the Magma, with 29-degree Comfort and 18-degree Lower Limit ISO ratings. This gap comes largely down to insulation: While the Magma packs 1 pound 7.3 ounces of 850-fill down, the Parsec uses just 1 pound 1 ounce of high-quality 900-fill down. The Parsec does make up some ground elsewhere: It uses a thicker 20-denier shell fabric, weighs more than 6 ounces less, and includes a true draft collar instead of an insulated yoke. It also tapers less through the body. While both offer similar shoulder room, the Parsec narrows to a 57-inch hip girth in the regular size, compared to the medium Magma’s 54 inches. Still, the Magma delivers more warmth for less money and comes in nine size options versus the Parsec’s three, making it a better value.
REI brings premium sleeping bag design to the masses with Magma, an 850-fill-power model at a reasonable price point. Throw in a plethora of size options—the most of any model we’ve seen from a major brand—and there is a lot to like about this bag.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
The Riff pairs nominally weight-saving materials with a comfort-minded mentality, but the results aren’t spectacular. This bag feels great, but we wish it leaned into either its roominess or packability even more.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
A three-season bag that undercuts much of the competition on price, the Parsec offers a competitive warmth-to-weight ratio, above-average durability, and a handful of thoughtful quality-of-life features. Roomy dimensions and the lack of a short size make it a less ideal fit for smaller users.
Warmth / Weight
Comfort
Features
Durability
Water Resistance
Sustainability
Is the Magma 15 for You?
The Magma makes sense for backpackers who are comfortable with a mummy-shaped sleeping bag and want something simple, straightforward, and that delivers strong value. It’s not a bag built around headline-grabbing specs or a long feature list, but it strikes a thoughtful balance between warmth, comfort, weight, and price. If you’re looking for a reliable, no-nonsense sleeping bag that covers a wide range of conditions without unnecessary complexity, the REI Co-op Magma is a nice choice.
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