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 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.
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 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.
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 quite attractive option in terms of overall weight, insulation weight, and feature set.
|Make / Model||Price||Down Fill Power||Total Weight||Down Fill Weight|
|REI Magma 15||$369||850||28.2 oz||15.9 oz|
|Feathered Friends Lark 10 UL||$579||950||31.3 oz||20 oz|
|Marmot Helium 15||$400||800||33 oz||19.8 oz|
|NEMO Kayu 15||$390||800||30 oz||15 oz|
|REI Igneo 17||$299||700||31 oz||16 oz|
|Therm-a-Rest Hyperion 20||$410||900||20 oz||13 oz|
|Western Mountaineering Badger15||$605||850||40 oz||23 oz|
|Western Mountaineering Apache 15||$540||850||33 oz||19 oz|
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 donated a sleeping bag for this review.SectionHiker is reader-supported. We independently research, test, and rate the best products. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.