Marmot Plasma 15 Sleeping Bag Review

Marmot Plasma 15 at Lunch Counter on Mt. Adams
This year I have been trying to carry less weight in the mountains and one area where I was able to reduce my weight was with my sleeping bag. I needed a 3-season sleeping bag that was warm enough for mountaineering but also light enough to take on fast and light overnight trips. Few sleeping bags are up to this task but the Marmot Plasma 15 is one of them.

The Plasma 15 uses 19.41oz of 875+ hydrophobic Fill Power Goose Down and the exterior shell is comprised of 10D Pertex Quantum Nylon. The Plasma line is all constructed by Insotect Flow baffles which in all practicality are simply vertical baffles. The sleeping bag weighs in at almost exactly 2lbs. Marmot claims 1lbs 15.96oz (906g), if you want exact details.

The Hood on the Plasma is something special to behold. Extra thick baffles contour around the head for maximum warmth and comfort. One of my favorite features of the bag is the chest draft collar. Many 15 degree bags omit this feature for cost savings, but the chest draft collar becomes exponentially important as the temperatures bottoms out to the sleeping bags limit. Being able to seal most of the warm air in and cold air out of the bag as you shift or move drastically keeps you warmer.
Insotect Flow: Cross-Section Diagram
Inostect Flow Diagram

How it Fits:
For being an ultralight sleeping bag, the Plasma 15 is still cut fairly comfortable. The best way to compare how the bag fits compared to other sleeping bags is to compare it against a few other UL sleeping bags.
Plasma 15 sleeping bag dimension comparison chart

The Plasma's dimensions are actually more roomy than other UL sleeping bags but more narrow than Marmot's middle of the road Sawtooth bag. I personally find the Plasma 15 to be exceptionally comfortable to sleep in compared to many other mummy shaped bags.
Marmot Xenon Left, Marmot Plasma 15 Right on a fall backpacking trip in the Cascades

An important thing to consider among sleeping bags is how subjective sleeping bag ratings are. I personally sleep usually cold so I usually look more at the women's comfort rating. The Plasma 15 has a comfort rating of 28.6°F / -1.9°C and a lower limit of 17.6°F / -1.9°C. For myself, the comfort level of the bag is around mid to high 20's.

The coldest I've used the bag was an October in central cascades at around 6400 elevation. I was using an Exped synmat 7 pad for those wondering what sleeping pad I paired with it. The Night cleared out and the temperature dropped to approx mid 20's. I slept fine wearing a mid weight synthetic puffy (Atom AR).

In the morning it rained causing what was a taught rain fly anchored into the snow to turn to mush. This caused the rain-fly to touch the tent. Several hours of rubbing the footbox against a damp tent certainly decreased the loft of the bag. I was glad I had a synthetic puffy! The Hydrophobic down does work considering there was still loft but my friend who borrowed my old Sierra Designs sleeping bag with a waterproof fabric had no decrease in loft. The whole sleeping bag industry has shifted to hydrophobic down but for wet trips or freeze/melt cycles, WP fabric on bags can't be replaced.

I've used the Plasma 15 on Mt. Baker, Mt. Adams, and Mt. Rainier. My wife and I shared the Plasma 15 sleeping bag in the Muir shelter to save on pack weight. We opened it up and layed it over our pads. For 2lbs, the bag provides a great bivy, just make sure to tuck down your side for less drafts.

This is new category that I designed for this sleeping bag. I have a hard time recommending this sleeping bag at 679$ when other brands like the Mountain Hardware Phantom 15, Feathered Friends Lark UL 10, Western Mountaineering Versalite, etc.. are over 100$ cheaper. The price-point on the Plasma should have been like 500-600$

I absolutely love the Marmot Plasma 15 sleeping bag. Over a year of use has shown how versatile this bag is, from UL backpacking to Mountaineering. It's feature packed with super plump baffles, chest and zipper draft collars, and UL Pertex Quantum fabric. The only downfall is the price.  The Plasma 15 is overpriced by over 100$ considering other UL bags in it's class.

Exceptional Bag, but comes with an exceptionally high price

  • 875+ Hydrophobic Down
  • Chest draft collar
  • Super plump head baffles
  • Yes please, on the Blue color!
  • Under 2lbs


  • Exceptionally expensive compared to other UL sleeping bags 
  • 679$ and it comes without a compression sack.... shame on you Marmot


  1. I need a best sleeping bag which you would be recommend for a Furious Traveler?

    1. Best as in warmest, value, light weight? How do you define best?


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