Reviews You Can Rely On

Marmot Hydrogen Review

A lightweight bag with an excessively narrow footbox
marmot hydrogen backpacking sleeping bag review
Marmot Hydrogen 30
Credit: Marmot
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Price:  $370 List
Manufacturer:   Marmot
By Jack Cramer ⋅ Review Editor  ⋅  Apr 23, 2020
  • Warmth - 20% 10.0
  • Weight - 20% 9.0
  • Comfort - 20% 7.0
  • Packed Size - 15% 10.0
  • Versatility - 15% 9.0
  • Features & Design - 10% 9.0

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.
Packs down really small
Low weight
Extra zipper for venting
Narrow footbox
Cheap hood drawstring
Fragile accessory zipper

Our Analysis and Test Results

Performance Comparison

marmot hydrogen backpacking sleeping bag review - 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.
Credit: Jack Cramer


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.

marmot hydrogen backpacking sleeping bag review - 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).
Credit: Jack Cramer


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.

marmot hydrogen backpacking sleeping bag review - 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.
Credit: Jack Cramer


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.

marmot hydrogen backpacking sleeping bag review - 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.
Credit: 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.

marmot hydrogen backpacking sleeping bag review - 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.
Credit: Jack Cramer


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.

marmot hydrogen backpacking sleeping bag review - 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.
Credit: 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.

marmot hydrogen backpacking sleeping bag review - 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.
Credit: Jack Cramer


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. We would still consider the Hydrogen if you're able to get it at a decent discount.

marmot hydrogen backpacking sleeping bag review - 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.
Credit: Jack Cramer


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
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