This plush, warm sleeping bag is appropriately named and the REI Co-op Magma 15. It may make you feel like you're sleeping in recently formed lava tube. Its lofty down fill creates a warm cocoon for sleeping in cool environments. Sometimes it is too warm, and we find it difficult to vent without having a shoulder exposed, which made it difficult to vent effectively without cooling down too much. REI doesn't share the logic behind the placement of the zipper which cuts in from the side to up the front of the hood at the top, but this was our least-favorite feature of this bag. We think the Magma is a good choice for cool weather camping and backpacking trips, but not our favorite.
REI Co-op Magma 15 - Women's Review
This super warm and lofty bag is a great choice for cool weather camping and backpacking, but we wish there was a more conventional zipper.
Price: $379 List | $379.00 at REI
Pros: Very warm, lofty, good value
Cons: Zipper design is uncomfortable and creates drafts, less compressible
Manufacturer: REI Co-op
Cons: Zipper design is uncomfortable and creates drafts, less compressible
Manufacturer: REI Co-op
By Jessica Haist ⋅ Review Editor ⋅ Oct 29, 2019
Our Editors independently research, test, and rate the best products. We only make money if you purchase a product through our links, and we never accept free products from manufacturers. Learn more
RELATED: The Best Sleeping Bags for Women
Our Verdict
Compare to Similar Products
Our Analysis and Test Results
The Magma will keep you warm just below freezing temperatures and is roomy in the legs, but the placement of the zipper is awkward and can be uncomfortable.
Performance Comparison
The REI Magma 15 will keep you warm on cool nights in the alpine.
Warmth
Warmth is the Magma's highest-scoring metric; it is very warm. We slept in it in the alpine of the Sierra Nevada in late September and were too hot! However, the placement of the Magma's zipper is strange. It winds from your right shoulder to the middle of your chin, so when the bag is partially unzipped, your neck and shoulder are exposed. The way the zipper is placed makes the bag feel cooler than a conventional zipper because it gapes open unless completely zipped up. Whereas with a conventional side-zip bag, you can still drape it over yourself unzipped, and it won't feel as drafty as when it's open up down your front.
The Magma 15 has a very warm 23.5 ounces of 850 fill to keep you warm at high elevations and on cool nights.
Weight
In the grand scheme of things, the Magma is a relatively light bag. However, if you're looking to shave off ounces in your lightweight kit, it is almost a half a pound heavier than the lightest competitors in this review. This is a trade-off for its impressive warmth offering.
The REI Magma is on the heavier side for longer trips into the backcountry.
Comfort
We love how cushy and lofty the Magma's 850 fill feels. The foot and leg area feels surprisingly roomy and comfortable. Unfortunately, the shape of the zipper is uncomfortable and caused lots of tossing and turning on our pads.
The Magma's asymmetrical zipper design means you have to have the bag completely zipped up or your shoulder and neck will be exposed, making this bag difficult to vent and uncomfortably drafty for side sleepers.
When the zipper is completely closed, the bag is very warm and cozy, but some people may feel claustrophobic as the hood is a very tight fit and comes right up to your mouth. As we mentioned already, it's hard to vent and difficult for side sleepers to stay warm unless it's fully zipped up because your shoulder sticks out of the opening.
We find the Magma's hood shape very fitted and it can feel claustrophobic when zipped up all the way.
Packed Size
The Magama is super lofty and is not as compressible as the other bags in this review with a similar or higher fill power. However, it does have more fill overall, which contributes to a bulkier bag (and a warmer one!). We couldn't fit this into some of the smaller stuff sacks that came with other products.
The Magma is not as compressible as other high-end down bags, but does have more down fill than most.
Features
We wish the Magma had an inner pocket! This is the one feature we really like in a sleeping bag so we can stash things like earplugs, headlamps, and phones.
We like the Magma's anti-snag zipper pull but wish the zipper didn't wrap around to the center of the bag.
As mentioned, we're not fans of the shape of the zipper. We think the neck baffle is silly and gets in the way unless the bag is fully zipped up. It sticks out because it's meant to cross over where the zipper comes up. If REI just made the zipper a normal shape, then they wouldn't have to create the annoying neck baffle feature. We do like that the Magma has snag-proof zipper pull.
The Magma's neck baffle is awkward because of the way the zipper is.
Value
In general, REI's products are of good value, and the Magma is no exception to this rule. We think it's a great value for a product with 850 down. However, we would still think some of the lighter and slightly more expensive products are a better value if trying to save weight.
We like how cushy and lofty the Magma is.
Conclusion
If you love completely zipping up your sleeping bag and feeling mummified in there at all times, the Magma will be a super warm and comfortable choice for you. Otherwise, we found the asymmetrical zipper design problematic in that it is very uncomfortable and creates drafts in your shoulder area if open at all.
— Jessica Haist