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Marmot Hydrogen Review

A lightweight bag with an excessively narrow footbox
Marmot Hydrogen
Photo: Marmot
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Price:  $341 List | $319.92 at Amazon
Compare prices at 2 resellers
Pros:  Packs down really small, low weight, extra zipper for venting
Cons:  Narrow footbox, cheap hood drawstring, fragile accessory zipper
Manufacturer:   Marmot
By Jack Cramer ⋅ Review Editor  ⋅  Apr 23, 2020
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66
OVERALL
SCORE


RANKED
#10 of 17
  • Warmth - 20% 6
  • Weight - 20% 8
  • Comfort - 20% 5
  • Packed Size - 15% 9
  • Versatility - 15% 6
  • Features & Design - 10% 5

Our Verdict

On paper, there's a lot to like about the Marmot Hydrogen. It weighs under 1.5 lbs (size Regular) and packs down impressively small while achieving a 24°F temperature rating on the industry-standard EN test. Our tests confirmed all of these claims but simultaneously uncovered some subtler flaws. The biggest complaint is the narrow dimensions of the footbox, which can make it feel uncomfortably constrictive. We also have concerns about the accessory venting zipper being prone to snagging and sewn directly into the bag, which would make any misalignment a seamstress-level repair. Nevertheless, if you can see past these flaws this bag could present an affordable way (compared to top-shelf bags) to trim some weight from your overnight kit.

Compare to Similar Products

 
Marmot Hydrogen
This Product
Marmot Hydrogen
Awards  Editors' Choice Award Top Pick Award   
Price $319.92 at Amazon
Compare at 2 sellers
$485 List$429.00 at Feathered Friends$389.00 at Feathered Friends$349.95 at Backcountry
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Pros Packs down really small, low weight, extra zipper for ventingSpacious dimensions, super comfortable, great loft, lightweight, made in the USASuper lightweight, incredible loft, snag-proof zipper, cozy hoodBest-in-class zipper, best-in-class hood, awesome loft, great warmth-to-weight ratioSpacious hourglass shape, innovative venting "gills", waterproof footbox, sturdy compression sack
Cons Narrow footbox, cheap hood drawstring, fragile accessory zipperExpensive, awkward hood, good but not great zipperUncomfortably narrow dimensions, bare-bones design, noisy fabricNarrow leg dimensions, no draft collar, heavier and bulkier than some 3-season optionsBelow average warmth-to-weight ratio, bulky packed size
Bottom Line An overly narrow footbox mires this otherwise great sleeping bagIf we could only have one bag for the rest of our lives, this would be itThe ideal bag when you need the warmth, but ounces matter tooExceptional warm and loft along with our favorite hood and zipperAn hourglass bag with premium down and spacious lower dimensions
Rating Categories Marmot Hydrogen MegaLite Hummingbird UL 30 Swallow 20 YF NEMO Riff 30
Warmth (20%)
6
8
8
9
4
Weight (20%)
8
8
9
7
7
Comfort (20%)
5
9
7
7
9
Packed Size (15%)
9
8
8
7
8
Versatility (15%)
6
7
8
8
8
Features & Design (10%)
5
7
7
7
9
Specs Marmot Hydrogen MegaLite Hummingbird UL 30 Swallow 20 YF NEMO Riff 30
Insulation 800+ FP Down 850+ FP Down 950+ FP Down 900+ FP Down 800 FP Down
Compressed Volume (L) 6.8 L 7.2 L 7.3 L 8.5 L 7.2 L
Measured Bag Weight (Size Long) 1.73 lbs 1.62 lbs 1.45 lbs 1.94 lbs 1.91 lbs
Manufacturer claimed weight of size Regular (lbs) 1.4 lbs 1.5 lbs 1.33 lbs 1.79 lbs 1.8 lbs
Compression/Stuff Sack Weight (oz) 0.8 oz 1.6 oz 0.8 oz 1.0 oz 2.4 oz
Hydrophobic down Yes No No No Yes
Manufacturer Temp Rating (F) 30 F 30 F 30 F 20 F 30 F
EN Temp Rating (Lower Limit, F) 23.4 F Not rated Not rated Not rated 29 F
Fill Weight (oz) 13 oz 13 oz 12 oz 17.5 oz 10.2 oz
Compression or stuff sack included? Stuff Stuff Stuff Stuff Compression
Shell material Pertex nylon ripstop (20D) Extremelite (12D) Pertex Endurance (10D) Pertex YFuse (20D) Ripstop nylon (20D)
DWR? Yes No Yes No Yes
Liner material 30D 100% nylon w/ DWR n/a n/a Pertex 20 denier nylon taffeta 30D nylon taffeta w/ DWR
Neck Baffle Yes No No No Yes
Small Organization Pocket Yes No No No Yes
Zipper 3/4-length / Side Full-length / Side Full-length / Side Full-length / Side 3/4-length / Side
Shoulder Girth (in) 61 64 58 60 62
Hip Girth (in) 56 Not stated 52 56 54
Foot Girth (in) Not stated 39 38 38 59

Our Analysis and Test Results

Performance Comparison


The Hydrogen is lightweight but narrow. That makes it ideal for...
The Hydrogen is lightweight but narrow. That makes it ideal for shorter backcountry missions where its constrictive feel won't have time to become too unbearable.
Photo: Jack Cramer

Warmth


Marmot leaves a nice buffer between the Hydrogen's advertised and tested temperature rating. They market it as a 30° bag while it receives a 23°F rating on the industry-standard EN test. As you might guess, our testers think it feels a little warmer than its advertised rating. It supplies this warmth with 13 oz of 800 fill power down, which is a decent amount considering the bag's narrow dimensions.

Despite the introduction of EN ratings, companies still chose the...
Despite the introduction of EN ratings, companies still chose the temp rating they market a bag at. Marmot leaves a nice buffer between the Hyrdogen's EN lower limit rating (23.4 F) and its marketed rating (30 F).
Photo: Jack Cramer

Weight


At 1.73 lbs for size Long (which we tested) and 1.4 lbs for size Regular, this bag is slightly ahead of the field in terms of weight. When you factor in its above-average warmth, it equates to an overall above-average warmth-to-weight ratio. This is surprising if you consider that the Hydrogen provides roomier dimensions and some additional features you won't find on other light bags that are fully optimized for minimum weight.

Cowboy camping under the stars is always a treat, but be wary of...
Cowboy camping under the stars is always a treat, but be wary of rain or dew with a down-filled bag like the Marmot Hydrogen.
Photo: Jack Cramer

Comfort


One of the ways the Hydrogen achieves its impressive warmth-to-weight ratio is through its narrow dimensions. With 61 inches of shoulder girth, the upper body section of the bag actually supplies adequate space. The same cannot be said as the bag tapers toward your feet. The footbox, in particular, feels uncomfortably constrictive. We also heard complaints about the drawcord used to seal up the hood. It's flimsy with a pointy melted tip that had a habit of floppy around and scratching our testers faces.

The svelte Hydrogen can compress impressively small. The included...
The svelte Hydrogen can compress impressively small. The included stuff sack, however, isn't designed to achieve maximum compression.
Photo: Jack Cramer

Packed Size


Considering this bag's near average weight, it performs impressively well when it comes to packed size. With the help of an aftermarket compression sack, we were able to squeeze it down to 6.8L, which is just fractions of a liter more than the smallest 3-season sleeping bags we've tried. The stuff sack it comes with, however, is of the simple drawstring variety so if you hope to enjoy the super small packed size we observed, you'll need to buy a third party compression sack.

This bag is distinguished by its 14-inch auxiliary zipper, seen here...
This bag is distinguished by its 14-inch auxiliary zipper, seen here on the left, which lets you shed heat better on a warm night.
Photo: Jack Cramer

Versatility


To boost your options for venting excess heat the Hydrogen is fitted with a 14-inch auxiliary zipper positioned opposite the main zipper near the head of the bag. When opened, this allows you to fold down the collar and let your neck and upper chest breathe. It's a nice feature, but we're not fans of the tiny zipper it relies on because it's so prone to snagging.

There's a small zippered pocket inside the bag to keep your...
There's a small zippered pocket inside the bag to keep your battery-powered electronics warm. This iPhone X barely fits inside.
Photo: Jack Cramer

Features & Design


Inside the bag is a slim zippered pocket that's just large enough to stash an iPhone X. The main zipper incorporates a Y-shaped slide that's designed to reduce snags. We found it to be modestly successful at this goal.

We're not happy about the hood drawstring made of supple string because it often dangles down to irritate your face. We also dislike that the useful accessory venting zipper is sewn fully into the bag which makes it a serious chore to fix if it becomes misaligned.

The main zipper is an effective Y-shaped design but the adjacent...
The main zipper is an effective Y-shaped design but the adjacent fabric is supple, rather than stiff, and susceptible to occasional snags.
Photo: Jack Cramer

Value


This bag retails near the average for a 3-season backpacking sleeping bag, and it's been around long enough that we occasionally see it on sale. At full price, we consider it an OK value, but there are a few other bags priced competitively that we like a little more, such as the 850 fill power REI Magma 30. If you're able to find the Hydrogen at a decent discount it could still be worth considering.

This auxiliary zipper on the Marmot Hydrogen boosts the bag's...
This auxiliary zipper on the Marmot Hydrogen boosts the bag's versatility, but its sewn fully into the bag. That means if it gets misaligned there isn't a easy way to fix it.
Photo: Jack Cramer

Conclusion


The sleeping bag market is a crowded place, and this bag does little to separate itself from the field. Its accessory zipper is perhaps its most distinguishing trait but this feature is compromised by durability concerns. If you're on a budget, the Marmot Hydrogen should be on your radar. But only if you're able to find it on sale.

Jack Cramer