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Marmot Phase 20 - Women's Review

This model will keep you warm and cozy at night, but comes with a hefty price tag
Marmot Phase 20 - Women's
Credit: Marmot
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Price:  $506 List
Pros:  Warmth-to-weight ratio, packs down small
Cons:  Expensive, restrictive in the leg area
Manufacturer:   Marmot
By Jessica Haist ⋅ Review Editor  ⋅  Oct 9, 2018
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  • Warmth - 25% 9.0
  • Weight - 25% 9.0
  • Comfort - 20% 8.0
  • Packed Size - 15% 8.0
  • Features - 15% 8.0

Our Verdict

Marmot updated the Phase 20 since our test period.

One of our testers called this bag her "Mermaid Bag" because she felt like one in this bright ocean blue bag with a tapered foot box that resembles a tail. We think the Marmot Phase 20 - Women's is a high-quality product that we enjoy having in the backcountry with us. It is lightweight and scores right up there with the top contenders in this category. It is surprisingly lofty and warm with 850 fill down, but also comes with a high price tag and a tight tapered ankle.

This is a great choice for all your lightweight backpacking needs. With the Phase, you can push your adventures into the shoulder season and camp from cool spring nights all the way through to crisp fall ones as well. It is not the best choice for very warm climates at the height of summer, but great for the mountains. While this bag has no major drawbacks, we found some other models to perform at the same level (or a smidge higher) for less cost.

Our Analysis and Test Results

We love the warmth and weight of this pretty sleeping bag, but don't like the price tag and restrictive fit around our ankles!

Performance Comparison

Marmot Phase 20 - Women's sleeping bag - the marmot phase 20 served us well on many alpine overnights and...
The Marmot Phase 20 served us well on many alpine overnights and backpacking trips.
Credit: Jessica Haist


The Marmot Phase is warm. With a fill power of 850, it has the loft and fluff you're likely seeking. The Phase offers a high level of quality down. Not only that, but the 18.3 ounces of it. The down fluffs up the inside of the bag, making it very warm. The Phase is almost too warm on mid-summer nights and we think it's EN rating of 21.7 is pretty accurate. If you live in warmer climates or are a fair weather camper, you could consider getting something that isn't quite as warm.

Marmot Phase 20 - Women's sleeping bag - the marmot phase is cozy and warm.
The Marmot Phase is cozy and warm.
Credit: Jessica Haist


For having so much down fill, the Phase is just a hair heavier than other lightweight competitors. While it is still lightweight enough to bring along on all fast and light backpacking adventures, it's not the lightest option out there.


We really love the Phase's soft liner materials that are fashioned in an attractive turquoise blue. One tester calls it her "Mermaid Bag" because of the color. She also called it that because of the strange, tapered foot box that almost looked like a mermaid tail.

Marmot Phase 20 - Women's sleeping bag - the phase's foot box is articulated at the toes and tapers at the...
The Phase's foot box is articulated at the toes and tapers at the ankle, which some might find claustrophobic for their legs.
Credit: Jessica Haist

If you are someone who doesn't like their legs to feel restricted, this bag is not for you. The foot box is articulated so you can have your ankles flex in it. However, it tapers down at the ankles leaving your legs feeling somewhat restricted. Another comfort feature we appreciate is the very large hood. If you cinch it down tight, it can essentially cover your whole face, wrapping you up in a cozy hug.

Marmot Phase 20 - Women's sleeping bag - the marmot phase is very comfortable with soft liner materials. we...
The Marmot Phase is very comfortable with soft liner materials. We enjoy sleeping in this bag.
Credit: Jessica Haist

Packed Size

The Phase comes with a small-ish sized stuff sack to pack it down. It is much more compressible than its sack suggests, though, and if you purchase a separate compression sack, you can get it down much smaller. It'll fit nicely into a backpacking backpack.


We like the Phase's simple features and the attempts Marmot has made at saving weight. It has a small inner pocket which we prefer for storing small things like earplugs and headlamps. The finish on the exterior of the bag is water resistant, holding up to moisture-laden mornings.

Marmot Phase 20 - Women's sleeping bag - the phase did a good job of beading moisture off when it got dewy...
The Phase did a good job of beading moisture off when it got dewy outside.
Credit: Jessica Haist

The troublesome feature on this bag which many people have complained about is its small-toothed zipper. It tends to catch on the shell material of the bag, requiring a lot of attention when zipping it up. Many products in this review now come with anti-snag zipper pulls to solve this problem. The other problem with this zipper is that it will not be compatible with other bags should you ever want to zip together with someone else!

Marmot Phase 20 - Women's sleeping bag - one set-back with this bag is its zipper. it has a tendency to catch...
One set-back with this bag is its zipper. It has a tendency to catch on the shell material.
Credit: Jessica Haist

Marmot Phase 20 - Women's sleeping bag - the marmot phase and the feathered friends egret are both great...
The Marmot Phase and the Feathered Friends Egret are both great options for long backpacking trips.
Credit: Jessica Haist


This area is the Phase's main downfall. It is at the higher end of the price range for products in this review. Many other high-quality bags in this review perform on par with the Phase and cost the same or less. As a result, the value isn't good.


If you want to feel like a Mermaid, and carry around a warm, lightweight bag on your back, the Phase could be the one for you. It has high-quality materials and will keep you warm through the seasons. Its shape is slightly restrictive around your legs, the zipper catches on occasion, and it has a steep price tag, but if you can overlook those facts, it gets everything else right.

Marmot Phase 20 - Women's sleeping bag - we like the phase's colors and feel like a mermaid in it sometimes.
We like the Phase's colors and feel like a mermaid in it sometimes.
Credit: Jessica Haist

Jessica Haist
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