REI Co-op REI Magma 15 Review
Brand: REI Co-op · Category: sleeping-bag · Price: $369 - $429
Buy the Magma 15 if you're a backpacker who wants a lightweight, compressible, and genuinely warm bag for three-season trips (spring, summer, fall). Skip it if you value an unrestricted fit or tend to run very hot in mild conditions.
Specs
| Shape | mummy |
|---|---|
| Length | Regular 72 in; Long 78 in |
| Weight | 1 lb 12.2 oz (men’s regular); 1 lb 14.6 oz (men’s long); women’s versions are heavier |
| Zippers | Left zip on men’s; right zip on women’s; anti-snag zipper with draft tube |
| Fill Type | 850-fill power goose down |
| Fill Power | 850 |
| Packed Size | 5.2 L compressed volume; roughly 7.5 x 15 in stuff sack |
| Shell Fabric | 15-denier Pertex Quantum ripstop nylon exterior; 15-denier nylon ripstop lining |
| Comfort Rating | 28°F |
| Temperature Rating | 15°F lower-limit rating; ISO comfort around 28°F; ISO extreme 17°F |
Strengths
- Excellent warmth-to-weight ratio for a true three-season down bag
- Lightweight and highly compressible for backpacking
- Premium feature set: draft collar, zipper draft tube, vaulted/trapezoidal footbox, variable baffles
- Available in multiple sizes and fits more body types than older REI bag designs
- Uses water-resistant, bluesign-approved, RDS-certified down and fabrics
- Strong value compared with many premium 850-fill competitors
Complaints
- Can be too warm for some users in midsummer without venting
- Price is high versus budget bags
- Mummy cut and fitted shape may feel restrictive to some sleepers
- Men’s and women’s size/weight specs can be confusing across versions and updates
- Not intended as a winter-expedition bag
- Some review sites report different weights and fill weights depending on size and model year
Fit And Comfort
The Magma 15's mummy shape and fitted design are part of what make it so warm and lightweight, as there's less empty space for your body to heat. However, this means it can feel restrictive for side sleepers or those who like to toss and turn. While REI has expanded its sizing offerings, if you crave a lot of room to spread out, you might find this less comfortable than a roomier bag like a semi-rectangular model.
Fill And Materials
REI loaded this bag with premium 850-fill power goose down. That '850-fill' number means the down lofts (fluffs up) really well, trapping a lot of air for insulation with less actual material. It's treated to be water-resistant, which is a huge plus if you encounter damp conditions, and is RDS-certified (making sure the down comes from humanely treated birds) and bluesign-approved (ensuring sustainable manufacturing practices). The shell fabric is a 15-denier Pertex Quantum ripstop nylon, which is a fancy way of saying it's a very thin but surprisingly durable fabric that resists tears and keeps the down from escaping.
Design And Features
This mummy bag is packed with features usually found on much more expensive bags, like a draft collar to seal in warmth around your neck and a zipper draft tube to prevent cold air from sneaking through the zipper teeth. The vaulted/trapezoidal footbox is shaped to give your feet more room to move naturally without compressing the insulation. The men's bag sports a left zip, while the women's has a right zip, making it easy to pair up if you want to zip two bags together (though you'll need the right corresponding zippers).
Weight And Packed Size
Clocking in at just 1 lb 12.2 oz for the men's regular, this bag is a true lightweight champion without jumping into ultralight, fragile territory. It also packs down impressively small, with a compressed volume of about 5.2 liters, or roughly 7.5 x 15 inches. This means it won't hog all the space in your pack, leaving room for more snacks or extra layers.
Warmth And Temperature Rating
The Magma 15 lives up to its name, offering serious warmth for its weight. It's rated at a 15°F lower limit, meaning it can technically keep you alive down to that temperature. However, the more realistic ISO comfort rating is around 28°F, which is what most people will find cozy. This makes it an ideal companion for shoulder-season outings or high-elevation summer trips where temps can still dip.