Lava deep underground is called magma. A sleeping bag that's unlikely to stay underground is the REI Co-op Magma 30. That's because this awesome bag is poised to become massively popular. On paper it has impressive specs: 850 fill power down in a 30°F bag that weighs just 1 lb 4 oz. Our hands-on test also confirmed that it achieves this low weight and respectable warmth without compromising comfort or versatility. Overall, the Magma isn't as good as our favorite models from Western Mountaineering and Feathered Friends, but it comes close. At the same time, the Magma has a more reasonable price tag, and its availability at REI means that you're much more likely to find it on sale. We thus recommend the Magma for dedicated backpackers or other weight-conscious travelers looking for a good bargain on a top-performing sleeping bag.
REI Co-op Magma 30 Review
Cons: Expensive, moderate warmth
Manufacturer: REI Co-op
Our Verdict
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 This Product
REI Co-op Magma 30 | |||||
| Awards |  |  | | ||
| Price | $320 List | $470.00 at Backcountry Compare at 2 sellers | $429.00 at Feathered Friends | $510.00 at Backcountry Compare at 2 sellers | $389.00 at Feathered Friends |
Overall Score  |
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| Star Rating | |||||
| Pros | Lightweight, small packed size, quality down, nice zipper, cozy fabric | Spacious dimensions, super comfortable, great loft, lightweight, made in the USA | Super lightweight, incredible loft, snag-proof zipper, cozy hood | Best-in-class warmth, legit draft collar, light weight, exceptional loft | Best-in-class zipper, best-in-class hood, awesome loft, great warmth-to-weight ratio |
| Cons | Expensive, moderate warmth | Expensive, awkward hood, good but not great zipper | Uncomfortably narrow dimensions, bare-bones design, noisy fabric | Really pricey, kind of bulky, awkward hood closure | Narrow leg dimensions, no draft collar, heavier and bulkier than some 3-season options |
| Bottom Line | A awesome bag at a fair price. | The only ultra-premium bag to combine low weight, good packability, and luxurious comfort. | Our favorite when ounces matter, this is a full-size mummy bag that's both warm and ultralight. | A ultra-premium bag that's our favorite for cold nights in spring and fall. | Our favorite zipper and hood in a bag that's also exceptionally warm and lofty. |
| Rating Categories | REI Co-op Magma 30 | MegaLite | Hummingbird UL 30 | UltraLite | Swallow 20 YF |
| Warmth (20%) | |||||
| Weight (20%) | |||||
| Comfort (20%) | |||||
| Packed Size (15%) | |||||
| Versatility (15%) | |||||
| Features & Design (10%) | |||||
| Specs | REI Co-op Magma 30 | MegaLite | Hummingbird UL 30 | UltraLite | Swallow 20 YF |
| Insulation | 850 FP Down | 850+ FP Down | 950+ FP Down | 850+ FP Down | 900+ FP Down |
| Compressed Volume (L) | 6.7 L | 7.2 L | 7.3 L | 8.7 L | 8.5 L |
| Measured Bag Weight (Size Long) | 1.39 lbs | 1.62 lbs | 1.45 lbs | 1.86 lbs | 1.94 lbs |
| Compression/Stuff Sack Weight (oz) | 0.4 oz | 1.6 oz | 0.8 oz | 1.6 oz | 1.0 oz |
| Manufacturer claimed weight of size Regular (lbs) | 1.24 lbs | 1.5 lbs | 1.33 lbs | 1.81 lbs | 1.79 lbs |
| Hydrophobic down | Yes | No | No | No | No |
| Manufacturer Temp Rating (F) | 30 | 30 | 30 | 20 | 20 |
| EN Temp Rating (Lower Limit) | 30 | Not rated | Not rated | Not rated | Not rated |
| Fill Weight (oz) | 9.7 oz | 13 oz | 12 oz | 17 oz | 17.5 oz |
| Shell material | Pertex ripstop nylon (15D) | Extremelite (12D) | Pertex Endurance (10D) | Extremelite (12D) | Pertex YFuse (20D) |
| Neck Baffle | Yes | No | No | Yes | No |
| Small Organization Pocket | No | No | No | No | No |
| Zipper | 3/4-length / Side | Full-length / Side | Full-length / Side | Full-length / Side | Full-length / Side |
| Shoulder Girth (in) | 63 | 64 | 58 | 59 | 60 |
| Hip Girth (in) | 57 | Unknown | 52 | Unknown | 56 |
| Foot Girth (in) | Unavailable | 39 | 38 | 38 | 38 |
| Compression or stuff sack included? | Stuff | Stuff | Stuff | Stuff | Stuff |
Our Analysis and Test Results
Performance Comparison
Warmth
The Magma is filled with 9.7 ounces of 850 fill power goose down. Although this down is undeniably high-quality, that's a fairly small amount for a bag with a 30°F temperature rating. Nevertheless, our testers believe this moderate rating is accurate. Helping it retain body heat is the legit draft collar that seals heat in on cooler nights. The Magma may not keep you lava hot, but it's certainly warm enough for most 3-season uses.
Weight
A size long weighed in on our scale at 1.39 pounds, impressively light for a 30° mummy bag with a full-length zipper. Its drawstring stuff sack also tipped our scale at an ultralight 0.4 ounces. Together they combine for an overnight combo that's noticeably lighter than several bags that offer similar warmth but cost as much as a hundred dollars more.
Comfort
The Magma scores pretty well on comfort. Its 63-inch shoulder girth is almost the widest we tested, and it only tapers modestly toward the foot of the bag. This left our testers with generous interior dimensions to enjoy. We also appreciated this bag's cozy 15-denier ripstop nylon material. Finally, it's easy to overlook the triangle-shaped piece of fabric at the end of the zipper, but the excellent job it does of shielding your face from the cold metal of the zipper's slide should not be ignored.
Packed Size
As its low weight would suggest, this bag packs down super well. Stuffed inside a third-party compression sack, we measured its minimum volume at 6.7 liters. That's nearly the smallest in the backpacking sleeping bag field. Unfortunately, you can't achieve this minimal size using the simple drawstring stuff sack that it comes with. So if packed size is important to you, expect to spend a few extra dollars getting a good after-market compression sack.
Versatility
All down insulation underperforms if it gets wet, and the Magma is no different. This limits its usefulness in wet conditions, but in most situations, it's possible to keep it dry and performing well. The range of temperatures you can comfortably use it in is enhanced by the full-length zipper and draft collar. The long zipper lets you vent excess heat on warmer nights while the draft collar helps trap heat inside on colder evenings.
Features and Design
As far as traditional mummy bags go, the Magma is designed pretty well. The strongest evidence for this is the respectable warmth it provides in such a lightweight package. Aside from that, however, it has limited noteworthy features. It lacks a stash pocket to store your phone, and it can't boast of any versatility boosting accessory. We do really like its zipper, which is anti-snag and includes a pull tab on the inside for a more convenient escape.
Value
The Magma is REI's premium sleeping bag offering. Although its price tag is higher than one might expect for a store-brand model, we still think it provides excellent value. Performance-wise there are a few ultra-premium bags from Feathered Friends and Western Mountaineering that we like more, but the Magma costs noticeably less. Its availability at REI also means that you're much more likely to find it on sale.
Conclusion
Today, more and more big-name companies are making sleeping bags with 850 fill power down or higher. Our testers have been underwhelmed with the offerings from many of these new entrants, but that's not the case with the REI Magma 30. Although its performance didn't quite reach the pinnacle of the backpacking sleeping bag category, it came darn close. Getting one at REI is also a lot more convenient than a custom order from a specialty manufacturer and improves the likelihood that you could find it on sale. If you're lucky and do find it marked down, don't hesitate to pull the trigger.
— Jack Cramer