Sleeping Bags

Marmot Helium Review

The Marmot Helium is a 15 degree down backpacking sleeping bag with winter temperature ratings that packs a lot of warmth for its weight. The 800+ fill goose down keeps weight down without going over the top on price.

The 20d inner shell reduces weight while the 30d outer shell increases water resistance and improves durability and longevity.

Coming in at almost 2lb’s (935g), the Marmot Helium is hard to fault, checking a lot of boxes for us looking for an ultralight, winter sleeping bag that can also fit into a small compression sack.

Marmot Helium 15 Sleeping Bag


  • Dual full length zipper
  • The design allows you to eat or read without the hood interfering.
  • 8/10 Warmth
  • Ultralight weight
  • Durable
  • Super comfortable cut – not too constricting
  • Compresses and packs down small
  • Top materials, especially silky liner fabric
  • High quality goose down – puffy!


  • Some minor cold spots, suspect draft tube design
  • Had to bounce included stuff sack for something more durable
  • Zipper could be lighter but at least its durable
  • Could have packed smaller with a 20d outer shell

Feature Summary

  • Ultralight Pertex – 20D ripstop with DWR finish for water resistance
  • Certified 800-fill goose down treated with Down Defender for improved performance in damp conditions
  • Second zipper adds ventilation and bag access options
  • Nautilus style hood envelopes your head in warmth
  • Anatomically designed footbox allows full loft around your feet
  • Insulated draft tube backs a full-length, 2-way, snag-free zipper to prevent cold air getting in
  • Stash pocket


The Helium is rated to 15f degrees and performs well down to around 20f without the need for added thermals. Below that you’ll need to add some thermal layers and maybe even a reactor sleeping bag liner. Provided you don’t try to push things past that, the helium will serve you well in your winter adventures.


I was actually kind of surprised to see this bag come in almost cracking below 2lb’s, the Helium has some solid materials and a few features you really don’t see at this weight range. Any lighter and you’d need to start looking at quilts – i.e. cutting it in half. And, yes, there are lighter sleeping bags out there, but they tend to use 950+ down which adds an extra $100 or $200 depending who you go with.

The Helium manages to also strike a balance with the shell fabrics going for something in-between stupid light and bomb proof, as long as you take care of this bag – it will take care of you.

Comfort & Sizing

The Helium has an absolute boatload of space in the upper portion of the sleeping bag, very nice for sitting up in your tent or around camp, the foot box is a bit more constrictive but that’s something I’m willing to give up for toasty feet all night long.

The Helium offers huge amounts of space where it’s needed and less where its not – this saves on weight but doesn’t effect comfort.

Marmot Helium Packed Size

The Marmot Helium packs down super small. You can get by with a 10L compression sack but I’d suggest going for something a little bigger for ease of packing – you can still compress down smaller than 10L.

Marmot Durability

Marmot produces some of the longest lasting sleeping bags I know of. I’ve had a Marmot trestles (synthetic) since my teen years and its still a great bag – although its lost a lot of warmth as the synthetic fibers broke down.

With the goose down filled Helium you don’t have that problem and the bag, with care, will last a very long time indeed.

Marmot Helium vs the Sawtooth

The Marmot Sawtooth is like the cheaper little brother of the Helium. Sporting 600 fill power duck down down and an 30d ripstop nylon shell it is almost one full pound heavier.

Check out this video on the differences between down and synthetic:

Marmot Helium vs Never Summer

The Marmot Never Summer is a warmer and much more bulkier version of the Helium. It’s a similar design but makes use of much more and lesser quality 600 fill power down feathers. Depending on your climate and expected weather forecasts, choose accordingly!

Marmot Helium vs Plasma

While Marmot Plasma is a little bit lighter and a little bit less bulky than the Helium I find the 875+ fill to be too little of an improvement to justify the price jump. I suggest either sticking with the Helium for your winter bag – its very good – and getting something in the 950+ fill power range for three season. I just can’t justify the Plasma over the Helium.

Marmot Helium vs Kelty Cosmic Down

Kelty’s Cosmic Down is a much cheaper option than the Marmot Helium but personally I shy away from recommending kelty products. They certainly have their niche, time, and place but they are generally cheaper for a reason. I personally trust marmot a lot more with its temperature ratings.

The Verdict

At around $400, the Marmot Helium is one of the more expensive marmot sleeping bags in its temperature rating range. But for what you get, I can’t really blame them. 850 Goose down, isn’t cheap and $400 is still a far cry less than some of the ultralight options out there.

The few downsides make this a solid choice for most people and I know you’ll be happy with it for many years.

Could it be lighter? Probably, but you would either have to lose some creature comforts in the shell (like space), or lose some down fill making it less warm overall?

I believe the Marmot Helium strikes a meaningful balance between affordability and features without skimping on quality.

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Frequently Asked Questions

How durable is the compression sack?

Not very, sadly marmot tends to make great quality gear and then drop the ball on things like compression sacks. Seems to be a common thread! Most people I know usually replace them with a Sea to Summit Event Dry bag anyway.

What is the volume of the sleeping bag packed up and compressed?

How far can you stretch a rubber band? You should be able to compress this sleeping bag down to around 7 litres, you could go further but you might end up damaging the down feathers.


Best UseBackpacking
EN Lower Limit13.5 degrees Fahrenheit
EN Comfort25.2 degrees Fahrenheit
Temperature Rating (F)15 degrees Fahrenheit
Temperature Rating (C)-9 degrees Celsius
Long Left
2 lbs. 4.5 oz.
Regular Left
2 lbs. 1 oz.
Zipper LocationLeft/Right
Insulation TypeDown
Water-Resistant DownYes
Fill800-fill goose down
Fill Weight
Long Left
22 ounces
Regular Left
19.8 ounces
Sleeping Bag ShapeMummy
Fits Up To (in.)
Long Left
78 inches
Regular Left
72 inches
Shoulder Girth (in.)
Long Left
63 inches
Regular Left
61 inches
Hip Girth (in.)
Long Left
58 inches
Regular Left
56 inches
Stuff Sack Size7 x 14 inches
Stuff Sack Volume8.8 liters