The Phase is easily one of the highest quality and best overall 20° F sleeping bags on the market. Its combination of a high-quality 10D Pertex shell fabric and top-tier water resistant 850 European goose down make this bag hard to beat, as its scored near the top of our review in nearly every category.
Performance Comparison
The Phase 20 was easily one of the warmest 20° F bags we tested. The only model that was warmer was the Western Mountaineering Ultralite, though it's worth noting that the difference in warmth between these two bags was minimal. The Phase is slightly lighter and more compressible.
Warmth
The Phase uses 14.1 ounces of top-quality 850 down fill that is hand-stuffed in Rohnert Park, California USA. On top of that, the down that Marmot uses is also treated with a proprietary DWR called Down Defender, which performed similarly to other water resistant downs in our review. It was noticeably more weather resistant and quicker drying than untreated down, helping to keep its user dry (for longer periods time) in wet conditions.
The Phase is straight-up one of the highest quality bags currently on the market - using quality materials and insulation to produce one of the lightest and most compressible 20° F bags out there.
We found the Phase was warmer than most bags in its temperature rating, with the exclusive exception being the Western Mountaineering Ultralite, which features 2 more ounces of similar fill-power down (and a slightly tighter and more thermally efficient cut that was noticeably warmer but was also 4.5 oz heavier). The Phase is slightly warmer than the Rab Mythic 400 and significantly warmer than the Kelty Cosmic Down 20, The North Face Cat's Meow, and The North Face Hyper Cat and provided significantly more warmth than the 5°F would suggest compared to the REI Co-op Igneo 25.
The comfort levels of the Phase - explained.
Besides more volume of generally higher quality down, the Phase's warmth was increased via its well-designed hood. Our entire review team loved the hood design of this bag both because we felt it effectively captured heat, but also because it was so dang comfortable. We felt this hood design added to this bag's versatility and proved especially important when pushing this bag near the edge of its temperature range while testing it on an early spring ski tour when the temperatures dipped into the upper teens.
The Phase featured one of the better hood designs in our review, not only doing a magnificent job retaining heat but also being among the most comfortable for our heads.
Weight
At just over 1 lbs 7 oz, this bag is impressively lightweight for its temperature rating and is one of the lighter weight 20° F bags on the market with only the Rab Mythic 400 being one-ounce lighter, but the Rab only features a 1/3 length zipper. Compared to its closest competition, the equally 20° F rated Western Mountaineering Ultralite, the Phase is still 4.5 ounces lighter, and offers a marginally more generous cut (though again the Ultralite has 2 more ounces of fill and did prove slightly warmer).
What's so impressive is the Phase weighs less than many bags rated to 30° F or warmer, including our other Editors' Choice, the 30° F Western Mountaineering MegaLite, (1 lb 8 oz, thought the Megalite is much roomier) and the Patagonia 850 down 30 (1 lbs 10 oz). The Phase achieves this exceptionally low weight both by using a some of the lightest weight shell fabrics in our review (10 Diner), very high-quality fill 850 down-fill, and a very low-gauge zipper. The Sea to Summit Spark III (1 lb 6 oz), which is only barely over an ounce lighter but isn't as warm nor as versatile, only features a 1/4 length zipper.
The Phase's dimensions are slightly on the tighter side, but pretty average among more performance-oriented sleeping bags. While it is marginally on the snug side, its roomy shoulder and hip dimensions mean the vast majority of people will find it plenty roomy.
Comfort
The shoulder and hip dimensions of this bag are 60" and 59", hardly making the Phase a "wide" bag. Overall, our testers found it struck a very nice balance between remaining light and efficient but also comfortable enough for most people, not feeling particularity narrower than most other performance sleeping bags.
The Phase is marginally wider than the Western Mountaineering Ultralite which sports a 59" shoulder girth and a 51" hip girth, but noticeable less roomy than the Editors' Choice the Western Mountaineering MegaLite.
While a small feature, the Phase featured among the best foot boxes in our review not only making back-sleepers more comfortable but also helping to keep their feet warmer while compressing less insulation.
Our review staff loved the feeling of this bag's internal fabric and found it among the most "silky" in the review. The one thing of note was on super warm days this fabric did feel a little clammier than most, but this was a minor complaint.
We like the small internal zippered pocket featured on the Phase as it was a decent place to keep a watch for an alarm, a small headlamp, or some lip balm.
Features & Design
The Phase also features a small internal zippered pocket that is a decent place to keep a small headlamp or a watch. We did notice that the loft of this bag muffled most watch alarms, so keep that in mind if you have an early wake up planned. This pocket isn't big enough to fit most smartphones. The WM Megalite, Ultralite, and Sea to Summit Spark offer numerous features and a well thought out design.
Packed Size
This model packs down the among the smallest 20° F sleeping bags you'll find on the market in our review and proved comparable to both the 25° F Sea to Summit Spark III and the Rab Mythic 400 which are only marginally more compact and both sports shorter 1/4 length zipper. The Phase blew the other competitors out of the water for compressed volume and often by a large margin, as it was half the packed size of the other bags with the same, or close to the same temperature rating.
The Phase even compressed down very similarly to our Editors Choice' Western Mountaineering MegaLite which is a 30° F bag. The phase comes with a small, lightweight stuff sack that does the best job of an included non-compression stuff-sack in our review, minimizing the amount of space the Phase takes up in your pack (without having to go out and buy an aftermarket compression sack). However, if you did use a different compression sack, you could make this bag roughly 25-35% smaller with an appropriate model.
Versatility
The Phase is an extremely versatile bag; it's lightweight enough for extended or long-range backpacking trips, yet has enough insulation (with enough extra room additional layers in its shoulder area) to help extend its temperature range. Thus, with a few additional layers, this bag works for colder lower-48 style mountaineering trips or spring ski touring trips. Conversely, the full-length provides excellent temperature regulation and can be opened up for warmer nights. When compared to the Sea to Summit Spark III, which was only two ounces lighter, we like the Phase for most purposes, as it offers a wider, more comfortable cut, as well as a full-length zipper.
Best Applications
The Phase is one of the best sleeping bags in our review for 3+ season use. It is more than adequately warm for most summer-time mountaineering in the lower-48 and lower regions of Canada, as well as multi-day spring ski touring missions though is still light and compact enough for even a thru-hiker to consider carrying.
Value
At $460, the Marmot Phase is one of the more expensive sleeping bags of its temperature both on the market, and in our review. However, from a quality and materials standpoint, we think there are exceptionally few bags using nicer down or shell materials. While this bag is expensive, it's fairly justified, as it's one of the nicest bags you can get. Even compared to other top-quality bags, the Phase is a high scorer and offers lightweight and generous dimensions. We also don't think the Phase gives up that much in the way of design, quality of workmanship, or materials. But again what sets the Ultralite apart from the Phase is the Ultralite is 100% crafted in San Jose, California, whereas the Phase is only stuffed and finished in the USA and sewn overseas.
The Phase 20 is one of the best 20F bags on the market. While expensive, it lives up to its price point, offering top-notch materials, insulation, and design - at a very low weight.
Conclusion
The Marmot Phase is easily one of the very best 20° F bags on the market and the same could be said about its 30° F counterpart, the Phase 30. Even compared to the best-of-the-best bags from Feathered Friends or Western Mountaineering, like the Ultralite, the Phase 20 is still lighter weight, roomier, and slightly more compressible (though marginally less warm than the Ultralite). From every standpoint, this is one of the very best sleeping bags currently available.
