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Therm-a-Rest Hyperion 20 Review

A seriously toasty bag to bring on any adventure that won't feel like a boat anchor in your pack
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Therm-a-Rest Hyperion 20 Review
Credit: Justin Simoni
Price:  $550 List
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Manufacturer:   Therm-a-Rest
By Justin Simoni ⋅ Review Editor  ⋅  Feb 28, 2024
76
OVERALL
SCORE


RANKED
#1 of 17
  • Warmth - 30% 9.0
  • Weight - 25% 6.5
  • Comfort - 20% 8.0
  • Versatility - 15% 6.0
  • Features - 10% 8.0

Our Verdict

If you're seeking the very best ultralight sleeping bag, your search may be over. After an exhaustive process of testing out a plethora of sleeping bags and quilts, we've settled on the Therm-a-Rest Hyperion 20 as the best. In hindsight, the reason why was obvious: the Hyperion uses some of the best materials, including 900 fill responsibly sourced, hydrophobic treated goose down sewn into DWR treated 10D nylon ripstop using horizontal box baffles and peppered with what we feel are some of the best-designed features for warmth and comfort. All this does come at a price — the Hyperion won't be easy on your bank account. But when you're ready to invest in a solid piece of gear, this is one we would not think twice about scooping up.
REASONS TO BUY
Excellent warmth and weight
Well thought out features
Horizontal box baffles
Generously-sized footbox
REASONS TO AVOID
Expensive
Not as versatile as a quilt

Compare to Similar Products

 
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$449 List
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Bottom Line Stay warm and comfy in this excellently executed bagThe only mummy bag that uses more down fill in the foot box and less around the torso, to take advantage of the clothing you have with youAn awesome set of features allows you to use this bagin a surprising amount of different temperatures and situationsA functional, versatile, and well-featured quilt well worth the low priceYour best bet for an ultralight quilt if down fill just doesn't work for you
Rating Categories Therm-a-Rest Hyperi... Feathered Friends V... Feathered Friends F... Hammock Gear Econom... Enlightened Equipme...
Warmth (30%)
9.0
6.8
4.0
6.7
5.5
Weight (25%)
6.5
8.5
7.4
4.8
5.3
Comfort (20%)
8.0
8.0
7.0
7.0
7.0
Versatility (15%)
6.0
6.0
10.0
8.0
8.0
Features (10%)
8.0
5.0
9.0
8.0
7.0
Specs Therm-a-Rest Hyperi... Feathered Friends V... Feathered Friends F... Hammock Gear Econom... Enlightened Equipme...
Manufacturer Stated Temperature Rating 20°F 25°F lower half, 45°F upper half 40°F 20°F 30°F
Measured Weight (bag only) 21.4 oz 16.2 oz 19.2 oz 25.8 oz 24.6 oz
Stuff Sack Weight 1.6 oz 0.8 oz 0.8 oz 0.6 oz 0.6 oz
Stuffed Size 6" x 8" 7" x 10" 7" x 10" 6" x 10" 8" x 17.5"
Manufacturer Claimed Weight 20.0 oz 16.7 oz 20.0 oz 22.2 oz 23.8 oz
Fill Weight 12.5 oz 9.4 oz 8.4 oz 13.2 oz 20.4 oz
Shell Material 10D Nylon RipStop w/DWR Pertex Endurance UL Pertex Endurance UL 20D nylon taffeta 10d Ultralight nylon fabric, DWR finish
Fill Power 900 fill RDS Nikwax hydrophobic goose down RDS 950+ fill goose down 950+ goose down 850 fill duck down 4oz/yd² Climashield Apex synthetic insulation
Style Hooded mummy Hoodless, zipperless mummy Center zip mummy bag or unzip for quilt Quilt Quilt
Construction Horizontal box baffle consruction No hood, no zipper and a variable fill Continuous baffles Box baffle consruction Baffle-less, no sewn-through seams
Shoulder Girth 57" 64" 62" 55" 54"
Hip Girth 49.5" 48" 48" 50" 47"
Foot Girth 43" 38" 39" 45" 40"
Zipper Length 1/2-length side zip at top No zipper Full-length center zip 1/3-length at bottom 1/4-length at footbox
Sizes Small, regular, long 62", 68", and 74" Regular, long, and wide Short, standard, long, short wide, standard wide, long wide Short, regular, regular wide, long wide
Temp Options (degrees Fahrenheit) 20, 32°F 25, 45°F 20, 30, 40°F 0, 10, 20, 30, 40°F 20, 30, 40, 50°F

Our Analysis and Test Results

Details matter, and the magic of the Therm-a-Rest Hyperion 20 is found in the excellent choice of materials and careful crafting of its features. The luxe 900 fill insulation traps your body heat to keep you pleasantly comfortable all night long, while the well-designed hood can be cinched down to keep the draft collar snugly around your face, sealing it from the cold air outside. For more temperate weather, the two-way half-length zipper can allow some much-needed ventilation for your body's core. All this in in a bag that weighs just 21.4 ounces. With the included compression sack, the Hyperion packs down small enough to get lost inside your pack and may feel so light you'll have to stop mid-hike just to double-check you didn't leave it at your last camp spot by mistake.

Performance Comparison


therm-a-rest hyperion 20 - this bag can spark pure joy when used on a camping trip - especially...
This bag can spark pure joy when used on a camping trip - especially when your feet experience its generous footbox.
Credit: Justin Simoni

Warmth


Toasty! Warmth is one of the most important metrics in our review, and the Hyperion 20 is the warmest bag in our lineup. It's easy to see why. It features 12.5 ounces of the finest responsibly sourced 900 fill goose down sewn into its horizontal box baffles using flyweight 10D shell fabric. An excellent 58% of this bag's weight is taken up by the down fill, which is exactly what provides all the insulating qualities.


Our overnight hot water bottle lab test resulted in the Hyperion coming up on top by a fair margin. The 20°F limit rating seems rooted in the real world — if not a little conservative — when we compared the results across all the bags we tested. The smart features found throughout the bag help keep warmth, like the clever and utterly simple pad attachment straps that keep a sleeping pad underneath you rather than wandering away and leaving your bottom exposed to the cold ground.

therm-a-rest hyperion 20 - these simple pad attachment straps do a great job of keeping your...
These simple pad attachment straps do a great job of keeping your bag attached to your sleeping pad, ensuring you're insulated from the ground.
Credit: Justin Simoni

Weight


We weighed the Hyperion 20 at 21.4 oz — a little heavier than the manufacturer's advertised specifications. Compared to other bags and quilts in this review, this is a good, but not great weight, but it is to be expected for a bag that's rated as low or lower, temperature-wise, than almost every other bag in our lineup.


All the features found in this bag are well-designed and don't take up much of the bag's total weight, especially the very lightweight 10D fabric used for the shell, which is as light as almost every other bag dares to go. Any lighter and you seriously run the risk of premature damage. A similar story can be told about the #3 zipper: anything smaller, and you're asking for trouble. Talking holistically, the designers made intelligent decisions to balance weight with performance.

therm-a-rest hyperion 20 - the included excellent compression sack allows you to pack the bag...
The included excellent compression sack allows you to pack the bag into a small volume, despite the 20F limit rating.
Credit: Justin Simoni

Comfort


Comfort reigns supreme with the Hyperion 20, not hurt by how much down fill is found within its baffles. The bag's measurements allow for a slightly more relaxed fit when compared to other ultralight sleeping bags in this category. This gave our main 5'11" climbing-obsessed tester a huge sigh of relief, as it's not always possible to fit his shoulders inside some of the more restrictive bags.


We can't help but repeat that all the features in the Hyperion are extremely well-designed and stay out of the way of you enjoying laying in this bag. We especially love the hood. When cinched down, it molds around the sleeper's head and feels comforting and supportive. A draft tube around the hood helps keep cold air from infiltrating. If things get too toasty, you can use the two-way zipper to vent from your hips to your chest while keeping the bag snug against your head, neck, and shoulders if you so desire.

therm-a-rest hyperion 20 - the hood can be cinched very tight around the head.
The hood can be cinched very tight around the head.
Credit: Justin Simoni

Versatility


Pure versatility isn't the strong point of the Hyperion 20. If that's what you need, consider a quilt, especially one that can transform into a flat blanket and several discrete steps in between. But as ultralight sleeping bags go, the Hyperion has some crafty tricks up its sleeve. Anchoring them all is its generous half-zip two-way zipper, which allows you to get in and pop out of the bag easily and provides multiple ventilation options if things are getting a little too hot.


The 20°F limit rating of the Hyperion means you can utilize this bag well into the shoulder seasons, where a lighter and higher temp-rated bag will fall short. There is a slight weight penalty to carrying a few more feathers than you need some of the time. That said, if you sleep colder than most, this bag could be perfect for summertime use.

Getting in and zipping up the Hyperion is quite easy, although you do have to be a little careful not to catch the small #3 zipper on the bag's fabric - no matter how smooth it looks for our handsome model.
Credit: Justin Simoni

Features


We could probably talk about the features of the Hyperion 20 as one does a hand-made watch. Small details go a long way in what we love about this bag. The high-quality materials of the 900-fill goose down and 10D shell fabric are a solid foundation upon which to build a great bag.


The two-way half-sized zipper is one of the best zippers we've found on a bag. We particularly love the position of the top snap at the head of the bag, which allows you to zip up or down any way you want while keeping the hood snug around your face. The cinch strap on the opposite side is out of the way, and stays out of the way, unlike so many other hood cinches we've tested. The bottom sleeping pad attachment straps are so useful and simple that we wonder why every bag ever made doesn't have something similar. We sleep better at night knowing we won't have to be rudely awakened to see just where our pad has wandered off to.

therm-a-rest hyperion 20 - a top hood snap and two-way zippers allow you to keep the hood tight...
A top hood snap and two-way zippers allow you to keep the hood tight around your head, while still allowing air to escape to regulate heat.
Credit: Justin Simoni

Should You Buy the Therm-a-Rest Hyperion 20?


If you're looking for the créme de la créme of ultralight sleeping bags, the Hyperion 20 rises to the top. The materials are quality, the features are refined, and, dare we say: this sleeping bag is close to perfection. If you can swallow the upfront price, it will serve you well for many miles and years to come.

therm-a-rest hyperion 20 - a bag to look at in wonder.
A bag to look at in wonder.
Credit: Justin Simoni

What Other Ultralight Sleeping Bags Should You Consider?


For a sleeping bag with comparable build quality to the Hyperion 20, look into the excellent Feathered Friends Hummingbird UL 30. It has a similar, more generous girth profile, which should benefit everyone whose trail name isn't prefixed with “skinny.” If you don't need as much space in your bag, the Sea to Summit Spark Ultralight 28 is another excellent option. It packs down just as well — or maybe even a little better — than the Hyperion, given it comes with its own excellent compression sack. For a quilt with a ton of excellent refined features, look no further than the Katabatic Gear Flex 22 Quilt. You may consider getting the “wide” option, as we found its main weakness is that the normal option was just a little too tight for our main tester's athletic build.

therm-a-rest hyperion 20 - the hyperion keeps us nice and toasty on a cold late autumn night...
The Hyperion keeps us nice and toasty on a cold late autumn night high on a snowy mountain pass.
Credit: Justin Simoni

Justin Simoni