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REI Magma 15 Down Sleeping Bag Review

REI Magma 15 Sleeping Bag

The REI Magma 15 is an ultralight sleeping bag for three-season use. Weighing just 1 lb 12.2 oz, it’s insulated with 850 fill power goose down with an outstanding warmth-to-weight ratio. Its variable-sized baffle construction, a draft collar, zipper draft tube, and trapezoidal footbox are all high-end features commonly found on premium sleeping bags costing much more. 

 Specs at a Glance

  • Gender: Men’s (a women’s specific version is also available)
  • Size: Regular
  • Weight: 1 lb 12.22 oz 
  • Down Fill Weight: 15.9 oz
  • Insulation: 850+ fill power goose down
  • Draft collar: Yes
  • Draft tube: Yes
  • Anti-snag Zipper: Yes
  • Water-Resistant Down: Yes
  • Fabric: exterior – Pertex Quantum; lining – 15 denier nylon ripstop
  • Shoulder/hip: 63”/57”
  • Length – Regular: 6’0” (72”)
  • Zipper: full length; left-hand
  • Stuff Sack Size/Volume: 7.5 x 15 inches/10.9 liters
  • Compressed size – Regular: 5.2 Liters
  • ISO Temperature Ratings:
    • Comfort: 28F / -2C
    • Lower Limit: 16F / -9C

The REI Magma 15 is a three-season sleeping suitable for use in spring, summer, and autumn although it may be too warm for use (without serious venting) in high summer, depending on your location and whether you’re a warm or cold sleeper. Its sweet spot is definitely in the cooler months during autumn and spring, when the days are shorter, the nights are cooler, and you need to a sleeping bag that will keep you warm as your metabolism slows during the longer nights. 

The REI Magma 15 has a distinct silhouette shape

The Magma 15 has what REI calls a curvy silhouette shape, that’s designed to save weight by eliminating the extra fabric and insulation that boxier sleeping bags require. While it is “fitted”, the Magma 15’s interior is not cramped and there’s still plenty of room inside regardless if you’re a back or side sleeper. The bag is however strongly shaped with a curved side-to-chest zipper and variable-sized baffles that help keep minimize the number and size of the air spaces in the bag that your body has to heat before you can get warm. 

Stiffened low profile strip next to the zipper reduce the chance of snags

Anti-Snag Zipper

The zipper on the Magma 15 is well designed and does not snag because it has a tightly woven barrier that keeps the down baffles away from obstructing the zipper’s path. The zipper extends from the bottom of the footbox and then angles up from about mid-chest, over the left shoulder to the neck/collar closure.  It has a robust pull loop and the teeth are encased in a hard plastic shell that slides easily for entry/exit or venting. 

The zipper is insulated with a down-filled draft tube which prevents cold drafts from reaching you

Interior

The inside of the Magma 15 is soft to the touch and constructed with a plush 15-denier nylon ripstop.  The baffles are variably spaced throughout the interior of the bag to maintain a high loft and minimize cold spots throughout the interior. The construction is not sewn through but uses a boxed style baffle adapted to work with the Magma 15’s unique shape. 

REI Magma 15 Yoke Draft Collar
The Magma 15 has a down baffle called a yoke that seals your neck and the top of your chest so hot air can’t escape.

Hood and Yoke

I usually wear a hat in a sleeping bag to ensure that my head stays warm even if I toss and turn at night. I found that I didn’t need a hat when using the Magma hood because it was so warm and well-fitting. The hood also followed me easily as I turned at night, rather than fighting against me as some mummy bags do. The hood is large enough to fit a pillow, which I find to be a must-have during the long cold nights of autumn and early spring.

The Magma 15 also has an insulated “yoke” that augments what is typically a fixed draft collar around the neck portion of a sleeping bag. It’s a baffle of down that lays on over your neck and upper chest to prevent warm air from leaking out of the bag when you move around at night, called the “bellows effect.” NEMO has a similar feature on all of their sleeping bags. They’re equivalent to draft collars but are slightly larger and easier to use without any additional adjustments. 

Comparable sleeping bags

When you compare the REI Magma 15 against other premium mummy sleeping bags, it is a quite attractive option in terms of overall weight, insulation weight, and feature set.

Make / ModelPriceDown Fill PowerTotal WeightDown Fill Weight
REI Magma 15$36985028.2 oz15.9 oz
Feathered Friends Lark 10 UL$57995031.3 oz20 oz
Marmot Helium 15$40080033 oz19.8 oz
NEMO Kayu 15$39080030 oz15 oz
REI Igneo 17$29970031 oz16 oz
Therm-a-Rest Hyperion 20 $41090020 oz13 oz
Western Mountaineering Badger15$60585040 oz23 oz
Western Mountaineering Apache 15$54085033 oz19 oz

Recommendation

The REI Magma 15 sleeping bag is a lightweight and relatively affordable option for those seeking to expand their backpacking adventures well into spring and autumn.  It is well constructed, weather-resistant, and comfortable when the nights are cold and long.  Weighing just 1 lb 12.2 oz, the Magma 15 provides superior warmth when temps get down into the 20’s and high teens while having little additional impact on the overall size or weight of your backpacking kit.  We’re impressed! 

Disclosure: REI provided SectionHiker with a sleeping bag 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.

About the author

Erik Birkeland is an avid hiker with a backpacking problem, that is, he just can’t seem to get enough. Living in Duluth, Minnesota with the Superior Hiking Trail just outside his backdoor, daily hikes and weekend treks fill his free time while he contemplates the next big adventure. He has completed numerous backpacking trips into such diverse landscapes as Escalante, the Wind River Range, the Absaroka-Beartooth Wilderness, the BWCA, Isle Royale National Park, and even Iceland. While he hasn’t gone the farthest, fastest, nor the ultra-lightest; he does aspire to establish as many trekking BKTs (best known times) as possible - meeting the wilderness as it is, by simply getting out there.

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12 comments

  1. Does is use RDS down?

  2. A friend of mine bought this bag for a Sept. Bonds traverse. He was cold with temps in the 30’s and he’s not a cold sleeper. I was warm in my Feathered Friends Flicker 30.

  3. Nice bag, detailed review, as usual. REI always gives you your money’s worth and then some.

    For the past 7 years I’ve had an overstuffed WM Megalite good to 20 F. and been very happy with it in the “shoulder seasons” and even summers her in the mountain west.

  4. I just bought a women’s magma 15 a few weeks ago (I’m a guy), and had a pretty warm and cozy sleep in it at about 22F nightly temps. In fact, I think I’m the only one out of a group of 4 that slept comfortably.

  5. I wonder why the women’s bag is heavier and more expensive? A long women’s ( 72 inches) is 2 pounds 6 ounces and $389.
    The men’s regular ( 72 inches) is 1 pound 12 ounces and $369 .

    • and though it says the women’s is roomier in the hip–both are measured at 60 inches. The men’s has 3 extra inches in the shoulders.

      • There are 8 more ounces of down in the womens than the mens. I don’t know any of the science here but i think the reasoning is something along the lines of; women sleep colder than men therefore require more insulation. Don’t know how true that is but it is common for womens bags to weigh more. I’m guessing that is why J.D. above got the womens version, to get some extra fill/warmth.

      • The science is that women sleep about 10 degrees colder than men because they have less body mass.

  6. Philip,

    What are your thoughts/experience with compression sacks for sleeping bags?

    I have the previous version Magma 10, and it’s 850 down compresses very well. But I am worried about damaging the down and reducing the loft.

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