The world's most in-depth and scientific reviews of outdoor gear

Marmot Phase 30 Review

One of the lightest and most compressible 30°F bags currently available, the Phase 30 is an excellent option for any trip where weight and packed volume are at a premium.
  • 1
  • 2
  • 3
  • 4
  • 5
Price:  $399 List | $299.25 at Backcountry
Compare prices at 4 resellers
Pros:  Extremely lightweight and the lowest weight model in our review, most compressible, cozy internal fabric, great hood design that is comfortable and traps heat
Cons:  Not super warm for its 30°F rating, side zipper catches
Manufacturer:   Marmot
By Ian Nicholson ⋅ Review Editor  ⋅  Nov 15, 2018
  • Share this article:
76
OVERALL
SCORE


RANKED
#8 of 17
  • Warmth - 20% 7
  • Total Weight - 20% 9
  • Comfort - 20% 6
  • Packed Size - 15% 9
  • Versatility - 15% 7
  • Features & Design - 10% 8

The Skinny

The Marmot Phase 30 is easily one of the best all-around backpacking and summertime mountaineering sleeping bags and was certainly a contender for our Top Pick for the best bag. Aside from just a couple of models, it was FAR lighter and more compressible than a majority of the competition and still. The only downsides of the Phase 30 are that it isn't a super warm 30°F bag and it sports some of the tightest internal dimensions in our review. However, for folks used to performance-oriented mummy-style bags, it feels similar to other mummy bags. Even our broad-shouldered testers who were used to sleeping in mummy-style bags didn't think it was much tighter than most.


Compare to Similar Products

Our Analysis and Test Results

The Phase 30 is a former award winner of our Top Pick Award for the best model for low weight and minimal packed volume. While it barely lost out this award to the Western Mountaineering Summerlite it was extremely close and this model remains one of the lightest and most compact 30° F models on the market. Overall the Phase is pretty tough to beat for those wanting a reasonably versatile bag that can embark on adventures where minimal weight and packed size are at a premium. The Phase isn't the warmest 30° bag out there and we felt like it was closer to a 35F rating than its stated 30F rating. However with that said aside from the Summerlite and the Mountain Hardwear Phantom Spark 28 it was almost half a pound lighter than most of its closest competition and was one of the most compressible models we tested.

Performance Comparison


The Phase 30 offers a low weight and excellent compressibility. While it certainly wasn't the warmest 30F bag out there  it wasn't far off and was almost half-a-pound lighter than its closest competition. Photo: Tracey Bernstein wakes up in Red Rocks Nevada after a cold Fall night.
The Phase 30 offers a low weight and excellent compressibility. While it certainly wasn't the warmest 30F bag out there, it wasn't far off and was almost half-a-pound lighter than its closest competition. Photo: Tracey Bernstein wakes up in Red Rocks Nevada after a cold Fall night.

Warmth


The Phase 30 uses 8.5 ounces of incredibly high-quality 850 fill power treated weather-resistant down. The proprietary treatment that Marmot uses id called Down Defender, and is hand-stuffed in Rohnert Park, California USA.

The 8.5 ounces is the least amount of fill weight found in any bag in our review. While it's high quality (thus having more loft and offering the best possible insulation for its weight) it wasn't as lofty as other 30°F sleeping bags in our fleet. While the Phase 30 has lots going for it, being an actual 30°F bag wasn't one of those things. It's excellent up to 40°F, though most of our testers found that we needed to layer up once we got into the 30°-35°F range.

The EN lower limit (rating for men) and EN Comfort Rating (rating for women) were the least warm for a 30F bag in our review. Our entire testing team agreed with those stats and felt it was rated closer to a 35-40F model.
The EN lower limit (rating for men) and EN Comfort Rating (rating for women) were the least warm for a 30F bag in our review. Our entire testing team agreed with those stats and felt it was rated closer to a 35-40F model.

Overall, the Phase 30 is similar in warmth to the Patagonia 850 Down 30, Sierra Designs Backcountry Bed 700, and The North Face Hyper Cat. However, we found all three of these bags were slightly warmer. Its close to, but not quite as warm as the Western Mountaineering Summerlite which is its more direct competitor. For those curious, the Phase was nowhere near as warm as the similarly rated (30°F) Western Mountaineering MegaLite, the Mountain Hardwear Phantom Spark 28 or the Nemo Salsa 30, which features a girthier cut.

It is worth noting that the Phase 30 is warmer than we'd expect of a bag offering only 8.5 ounces of fill; this is due to the model's tight cut and exceptionally well-designed hood, which did a top-notch job at trapping the heat and was comfortable. The same could be said about the vaulted foot box that minimizes the amount of down compressed around our feet, maximizing warmth. It's not that this bag isn't warm; it's just not as toasty as most other 30F models we tested.

The Phase 30 featured one of our favorite all-around hood designs. The hood wrapped comfortably around our heads without making us feel claustrophobic and did a top-notch job of trapping heat.
The Phase 30 featured one of our favorite all-around hood designs. The hood wrapped comfortably around our heads without making us feel claustrophobic and did a top-notch job of trapping heat.

While it shares the same name as its colder weather sibling the Phase 20; most of the things mentioned above (about it not being warm enough for its temperature rating) don't apply. The Phase 20, despite being one of the lighter 20F bags out there and is one of the warmest in our fleet. The Phase 20 achieves this by using 14.1 ounces of high-quality down, which is more than nearly every model we tested.

The Phase 30 uses top-quality 850 fill European goose down that is hand-filled in the USA. Marmot also uses a water resistant treated down called Down Defender (what a great name)  which uses a proprietary chemical that performed similarly as other treated weather resistant downs.
The Phase 30 uses top-quality 850 fill European goose down that is hand-filled in the USA. Marmot also uses a water resistant treated down called Down Defender (what a great name), which uses a proprietary chemical that performed similarly as other treated weather resistant downs.

Weight


At just over 1 lbs 1.5 oz (498g), the Phase 30 is one of the lightest bags for its temperature rating on the market and is barely the lightest model in our review being almost an ounce lighter than the Western Mountaineering Summerlite and a couple ounces lighter than the Mountain Hardwear Phantom Spark 28 and Sea-to-Summit Spark III but otherwise significantly out-performing the vast majority of the competition in this category.

The Phase 30 weighs less than many bags rated to 40°F and is one of the lightest 30F models currently available. The Phase is an impressive 6-7 ounces lighter than other lightweight models, including our Editors' Choice, the Western Mountaineering MegaLite, (though the Megalite is roomier), and the sewn through Patagonia 850 Down 30.

The Phase achieves its low weight by using high-quality down; equipped with 8.5 ounces, along with a 10D shell fabric, this is among the thinnest material of any model we've tested. While it does feature a full-length zipper, the zipper Marmot uses is small, making it lighter and more packable, but also more prone to hanging up.

The internal fabric on the Phase was among our favorite in the review. It was silky smooth and didn't feel as clammy as most other models we tested.
The internal fabric on the Phase was among our favorite in the review. It was silky smooth and didn't feel as clammy as most other models we tested.

Comfort


This bag's dimensions are 60" (shoulder), 59" (waist), and 45" (feet). Not exactly a "wide" bag. When compared to other performance-oriented mummy-style bags, it's not exactly narrow, either.

If you like most things about the Phase but wish it was a little roomier, we'd recommend considering our Editors' Choice Western Mountaineering MegaLite, which sports four more inches of room in the shoulders and 6.5 more ounces. What does four more inches of circumference feel like? We instantly noticed the additional space that gave us a tad more room to roll around in; it also does not feel as claustrophobic, especially if mummy bags tend to give you that impression.

Overall  our review team found the Phase 30 struck a very pleasant balance between weight and comfort. While hardly a wide-dimensioned bag  it was maybe only slightly smaller-than-average when compared to most performance oriented sleeping bags.
Overall, our review team found the Phase 30 struck a very pleasant balance between weight and comfort. While hardly a wide-dimensioned bag, it was maybe only slightly smaller-than-average when compared to most performance oriented sleeping bags.

We loved the incredibly silky feel of the interior fabric, which was among the very best in our review. Our review staff loved using the Phase 30 when it was hot (we felt less clammy); when it was cold out, the 30 felt cozier than the majority of models out there.

We loved most of the design features that went into the Phase 30. The only very small thing we didn't like is that the extremely low-gauge zipper (low gauge to save weight) gets snagged on the material more than any other bag we tested. This is hardly a deal breaker but was a small pain worth noting.
We loved most of the design features that went into the Phase 30. The only very small thing we didn't like is that the extremely low-gauge zipper (low gauge to save weight) gets snagged on the material more than any other bag we tested. This is hardly a deal breaker but was a small pain worth noting.

Features & Design


There aren't many "extra" features on this bag, and most of the design has been geared towards making it as light and compact as possible. The Phase 30 uses the highest quality down, as well as the minimal amount of fill to achieve a 30F rating. It includes a top-notch hood design to increase its thermal efficiency.

Despite its overall pretty minimal design  the Phase features a small internal zippered pocket. While this pocket was too small for a smartphone  it was a great place to keep a watch or a headlamp to help keep these items from getting lost in the dark.
Despite its overall pretty minimal design, the Phase features a small internal zippered pocket. While this pocket was too small for a smartphone, it was a great place to keep a watch or a headlamp to help keep these items from getting lost in the dark.

There is a tiny internal zippered pocket for an alarm or a watch (if you sleep on your back), but it isn't big enough for most smartphones. Marmot uses a small gauge zipper to help save weight and lines the full-length of this zipper with a marginally stiffer fabric. They call the material "snag free" and say it helps reduce the frequency of the zipper catching on the bag's ultra-thin fabric. Unfortunately, the zipper on our model got hung up and easily snagged.

Showing the size of the Phase 30 when it is stuffed inside its included stuff sack. While it isn't the smallest stuffed sleeping bag we tested  its hard to complain about this size.
Showing the size of the Phase 30 when it is stuffed inside its included stuff sack. While it isn't the smallest stuffed sleeping bag we tested, its hard to complain about this size.

Packed Size


The Phase 30 is easily among the most compressible models in our review. It's 25% smaller than our Editors' Choice the Western Mountaineering MegaLite or Patagonia 850 Down 30, and half the size of other models like the Nemo Salsa 30, or the Sierra Designs Backcountry Bed 700. The only contenders that were comparable was the Mountain Hardwear Phantom Spark 28 and the Western Mountaineering Summerlite along with the slightly warmer Sea to Summit Spark III, which was around 10-15% larger in packed volume.

Versatility


The Phase is a pretty darn versatile bag - as long as it's not too cold. Despite its low weight, features a full-length zipper that allows you to regulate heat on warmer nights.

The Phase 30 features continuous baffles that allow you to shift the down around, though we doubt many people would do this (since there's such little down to begin with). Even our most broad-shouldered reviewers found that its average dimensions (among performance mummy bags) were still plenty to accommodate wearing several layers. This bag is versatile in the sense that it works well in a reasonably wide range of conditions. It can be taken on most outings where weight and packed volume is paramount; as long as the overnight temperatures are reasonable, it also makes for a decent car camping bag.

The Phase 30 is a great addition to your ultralight kit and is versatile enough to stretch into three season use  while also offering solid resistance against water and condensation.
The Phase 30 is a great addition to your ultralight kit and is versatile enough to stretch into three season use, while also offering solid resistance against water and condensation.

Best Applications


The Phase is one of the best contenders in our review for lightweight backpacking, thru-hiking, summer-time mountaineering, or any other activity where low weight and minimal packed size will be appreciated. This bag is comfortable enough for most general purpose backpacking and camping, but other models are marginally roomier if low weight and packed size aren't big factors for you. The only thing that stops this bag from being more versatile for a wider range of activities is most people will find this bag comfortable down to 35°-40°. If the temperatures are any colder, additional layers will need to be used.

Value


At $399, the Phase 30 is pricey, but we feel it has the quality down and shell materials to back it up and with its impressively low weight is one of the highest performing 30°F bags out there. Compared to other high-end bags, the Phase scores similarly and offers extremely low weight and decently comfortable dimensions while being close behind the Phase 30 in design and material quality. The WM Megalite is sewn and filled in California, while the Phase is filled and finished in the USA, but is primarily sewn overseas.


Conclusion


The Marmot Phase 30 is one of the lightest and most compressible 30F sleeping bags on the market though it makes some sacrifices in warmth and we felt we needed to add a layer in this model sooner than other similarly rated bags. While it might not be a do-everything well model, it's a bag that excels at any activity where low weight and pack space are at a premium and it isn't going to be cold, which in reality is probably the majority of trips for people out there. If temperatures are expected to be much colder than 30 degrees, you'll need to pack extra layers or sleep in your clothes. This model compares closely with the Western Mountaineering Summerlite and most people considering this bag should also consider that bag which is ever-so-slightly heavier, but slightly warmer.


Ian Nicholson