Reviews You Can Rely On

REI Co-Op Magma 10 Review

While not the warmest, this bag is the lightest bag in our review and features high-quality down at a great price
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REI Co-Op Magma 10 Review
Credit: REI
Price:  $379 List
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Manufacturer:   REI
By Matt Bento ⋅ Review Editor  ⋅  Feb 5, 2019
  • Warmth - 20% 4.0
  • Weight - 20% 10.0
  • Comfort - 20% 6.0
  • Packed Size - 15% 9.0
  • Features - 10% 6.0
  • Weather Resistance - 15% 7.0

Our Verdict

The REI Co-Op Magma 10 is a good bag for the minimalist backcountry adventurer on a budget or the reluctant winter camper who wants to spend a few nights out this season without leaving their wallet as cold and empty as the arctic tundra. For the price, this bag is extraordinarily lightweight and compressible. Our testers agreed that the 10º rating was a little generous and felt that this back is much better suited for temps in the low 30s and upper 20s. If you're willing to add more weight to your pack and keep more money in your wallet, check out the less expensive, Best Buy-winning Therm-a-Rest Questar 0.
Good weather resistance
Not as warm as other bags with similar temperature ratings
New Version

The Magma 15 is the latest offering from REI. Read on to learn about the differences between the Magma 10 and 15.

February 2019

Our Analysis and Test Results

Magma 15 vs. Magma 10

REI replaced the Magma 10 with the new Magma 15. The bag still utilizes 850-fill down, just slightly less of it, making it almost 2 ounces more lightweight. The two seem very similar, excepting for the obvious temperature difference. The newer bag has a temp limit of 16°F, compared to the previous bag's 10°F lower limit. The Magma 15 is shown on the left, and the old Magma 10 on the right.

We link to the Magma 15 in this review, but as we have not actually cozied up in this new bag, the following review still pertains to the Magma 10.

Hands-On Review of the Magma 10

The REI Magma is the lightest in our review, but it's also less warm than similarly priced bags, especially when compared with our Best Buy Award winner, the Thermarest Questar 0. The Western Mountaineering Versalite is rated to 10º, and it feels much warmer than the Magma. Out the box, this bag impressed our testers with its loft, rivaling some Western Mountaineering models, for around half the price.

rei co-op magma 10 - our testers were psyched on this 850-fill down bag at a great price.
Our testers were psyched on this 850-fill down bag at a great price.
Credit: Matt Bento


The 10º rating on this bag is representative of the lower limits of this bag. The Western Mountaineering Versalite is also rated to 10º, but it has 2.5 more ounces of down, making it loftier and providing a thicker layer of heat-trapping feathers. If your winter climate is typically mild and dry, and temps aren't dipping below the mid-teens, this bag is a good super lightweight choice. For summertime alpinism or “alpine-light” adventures in the Sierra, this bag has a great warmth-to-weight-to-price ratio.

rei co-op magma 10 - this bag is available in three sizes: fitted, regular, and wide. you...
This bag is available in three sizes: fitted, regular, and wide. You can choose to prioritize weight savings or comfort.
Credit: Matt Bento


Weight is this bag's strong suit, and rarely have we seen an 850 fill power down bag at a sub $400 price range. 17.6oz of the total weight of the bag is down, leaving 12.4oz dedicated to the material weight. The shell is comprised of lightweight Pertex Quantum, which feels so thin and light that one tester commented that she felt like she was sleeping in a garbage bag (as far as weight was concerned). The Magma is available in three sizes, fitted, regular, and relaxed. This means that you can trade comfort and space inside the bag for even more weight savings. The Magma and Western Mountaineering Versalite were the two lightest bags in the fleet.


Our test model is the “regular fit” version of the Magma. We like the roomy foot box, where you can relish in the extra space for your tired feet, or store a hot water bottle or some clothing that needs to stay warm. The hip girth measurements on the Magma are wider than our Editors' Choice Award winner, the Western Mountaineering Kodiak MF, but the taper of the Magma is different, making it more difficult to bend our legs up to our chest, and generally making this bag feel a bit narrower.

rei co-op magma 10 - this bag packs down smaller than any other bag in our review.
This bag packs down smaller than any other bag in our review.
Credit: Matt Bento

Packed Sized

This bag packs down as small as any other bag in our review, making it great for alpine adventures, backpacking, bike touring, traveling, or any activity where space is a premium. It packs down pretty small in its included stuff sack, but in a proper compression sack, it compresses to the size of a cantaloupe. A similar packed size is found in the Versalite.

rei co-op magma 10 - appropriately called the "zipper plow", this zipper operates...
Appropriately called the “zipper plow”, this zipper operates completely snag free.
Credit: Matt Bento


We feel like a lot of the price, and weight savings comes from a lack of features. The Magma has one cinch cord for the hood and collar that slips open too easily when we jostled around and didn't seal up all the way over your face. This is important for sleeping out in the wind, and all our favorite bags close up so that only your nose sticks out. Instead of a full draft collar that encircles your neck, the Magma has an “insulated yoke” that hangs down under the chin and doesn't keep out the cold air as well as a collar. The Magma has a sweet zipper that has a guard on the top of it, ensuring snag-free operation.

rei co-op magma 10 - light rain and snowmelt are no match for the pertex quantum shell.
Light rain and snowmelt are no match for the Pertex Quantum shell.
Credit: Matt Bento

Weather Resistance

The Magma stays dry with the best of the fleet in our light rain testing. Water beaded up and eventually puddled on the shell of this bag. The Pertex Quantum shell kept the interior dry, even at the seams, just as well as more expensive bags, but not as well as the super burly Marmot Col or the Feathered Friends Snow Bunting.

rei co-op magma 10 - always store your down bag in a storage sack to ensure years of...
Always store your down bag in a storage sack to ensure years of lofty warmth.
Credit: Matt Bento


For the price, this bag is an awesome value. You won't find many bags this lofty with 850 fill power down for that price, especially with such lightweight and weather-resistant shell materials. It was right on the line of winning one of our Best Buy Awards.

rei co-op magma 10 - comfortable at 22, "t" for tolerable at 10.
Comfortable at 22, “T” for tolerable at 10.
Credit: Matt Bento


If you're looking for something lightweight and easy on the wallet, the REI Co-Op Magma 10 is a solid choice, especially if you consider yourself a warm sleeper. Available in three sizes, there's something for everyone, whether your top priority is weight savings or comfort.

Matt Bento