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Therm-a-Rest Hyperion 20 Review

This super-lightweight, compact bag is a great choice for fast and light, warm-weather adventures but does sacrifice some comfort and warmth for weight
Therm-a-Rest Hyperion 20
Credit: Therm-a-Rest
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Price:  $470 List | $352.46 at Backcountry
Compare prices at 2 resellers
Pros:  Very lightweight, small packed size, high-quality down
Cons:  Tight-fitting mummy bag, not very warm, expensive
Manufacturer:   Therm-a-Rest
By Jessica Haist ⋅ Review Editor  ⋅  Oct 20, 2021
Our Editors independently research, test, and rate the best products. We only make money if you purchase a product through our links, and we never accept free products from manufacturers. Learn more
72
OVERALL
SCORE


RANKED
#8 of 17
  • Warmth - 25% 4.0
  • Weight - 25% 10.0
  • Comfort - 20% 5.0
  • Packed Size - 15% 10.0
  • Features - 15% 8.0

Our Verdict

The Therm-a-Rest Hyperion is a great lightweight bag for fast summertime adventures. It is much lighter than most bags we’ve tested, but it’s also nowhere near as warm as most other products in this review. This trade-off will be worth it for those of you looking to go super light in the warm summer months where temperatures do not go below freezing. Its scant weight and tiny packed size make it a great candidate for long trips and moving fast. We love its high-quality down fill and clever half-zip design, but its price tag and niche use will give some people pause.

Compare to Similar Products

 
Awards  Editors' Choice Award Editors' Choice Award Best Buy Award Best Buy Award 
Price $352.46 at Backcountry
Compare at 2 sellers
$569 List
$489.00 at Feathered Friends
$569 List$330 List
$254.96 at Amazon
$113.37 at Backcountry
Compare at 3 sellers
Overall Score Sort Icon
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Star Rating
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Pros Very lightweight, small packed size, high-quality downHigh-quality down, warm, lightweightHigh-quality down, warm and lofty, light, a top tier productComfortable, lightweight, excellent materials, not constrictingLight and compressible synthetic, keeps you warm when wet
Cons Tight-fitting mummy bag, not very warm, expensiveSizing not for everyone, fabric is a bit noisyExpensiveComforter sometimes does not stay tucked inBulkier packed size, heavier, small fit
Bottom Line This super-lightweight, compact bag is a great choice for fast and light, warm-weather adventures but does sacrifice some comfort and warmth for weightThis high-end bag will keep you warm and comfortable from Spring to Fall in all conditionsA high-tech, high-quality backpacking sleeping bag with more roomy dimensions than mostA great, high-quality choice at a relatively low price for those looking for a lightweight bag that doesn't sacrifice comfortAn inexpensive and versatile synthetic bag, this is an excellent choice for breaking into backpacking
Rating Categories Therm-a-Rest Hyperi... Feathered Friends E... Sea to Summit Flame 15 Sierra Designs Clou... The North Face Cat'...
Warmth (25%)
4.0
10.0
9.0
5.0
8.0
Weight (25%)
10.0
9.0
8.0
9.0
6.0
Comfort (20%)
5.0
8.0
9.0
8.0
8.0
Packed Size (15%)
10.0
8.0
9.0
9.0
6.0
Features (15%)
8.0
9.0
8.0
8.0
7.0
Specs Therm-a-Rest Hyperi... Feathered Friends E... Sea to Summit Flame 15 Sierra Designs Clou... The North Face Cat'...
ISO/EN Comfort Rating 32 F 20 F (not EN rated) 15 F 26 F 22 F
Fill Type 900-fill-power Nikwax Hydrophobic goose down Goose down Goose down PFC-Free DriDown Heatseeker™ Guide synthetic insulation
Measured Weight 1.2 lbs. 1.7 lbs. 2.0 lbs. 1.7 lbs. 2.5 lbs.
Total Weight 19.0 oz. 27.5 oz. 31.2 oz. 27.4 oz. 40.2 oz.
Fill Power 900 950+ 850+ 800 Synthetic
Women specific features Available in a "Short" length, which is a standard women's size Extra fill in footbox and chest Women's specific fit - more insulation in key areas More insulation per square inch than men's version Women's specific cut
Fill Weight 12.0 oz. 17.3 oz. (medium) 22.9 oz. 14.8 oz. Unspecified
Material 10D Nylon RipStop w/ DWR Pertex Endurance UL Ultralight 10D Nylon Shell 15d nylon risptop 20D Nylon Ripstop/taffeta
Neck Baffle No Yes Yes No Yes
Pocket No No No No No
Sleeping Pad Sleeve Removable attachment straps No No Yes No
Zipper Length 35 in 62 in 56 in N/A 59 in
Shoulder Girth 55 in 54 in 60 in 59 in 58 in
Hip Girth 48.5 in 56 in 58 in 58 in 58 in
Foot Girth 36 in 38 in 40 in 39 in 40 in
Stuff Sack included? Compression sack and storage bag included Stuff sack and storage bag included Compression stuff sack and storage bag included Stuff sack and storage bag included Compression sack and storage bag included

Our Analysis and Test Results

The Hyperion is a great choice for warm-weather, lightweight backpacking adventures. If you’re looking to move quickly with a lightweight pack, this could be the bag for you.

Performance Comparison


Therm-a-Rest Hyperion 20 sleeping bag womens - the therm-a-rest hyperion is a great choice for fast and light...
The Therm-a-Rest Hyperion is a great choice for fast and light adventures.
Credit: Ian McEleney

Warmth


Because it is a unisex model, the Hyperion’s temperature rating is different from the other bags in this review. Therm-a-Rest rates this bag to the EN “Limit” rating, which in this case is 20F versus the “Comfort” rating of 32F. This is different from the other women’s specific bags we’ve tested, which use the “Comfort” rating in their naming conventions, but seems to be the way that Thermarest rates all their bags. This is definitely something to note when you’re comparing the Hyperion to other products in this review. This bag’s Comfort rating is to 32 F. We took it out on a chilly September night and we’d say that rating is just about right. As the temperatures dipped towards freezing in the wee hours of the morning we felt chilly but never cold. We like the Hyperion’s half zip as it prevents drafts coming through the zipper and its snug hood does the same.

Therm-a-Rest Hyperion 20 sleeping bag womens - the hyperion's snug hood helps keep warmth in, as does its...
The Hyperion's snug hood helps keep warmth in, as does its tight-fitting silhouette.
Credit: Ian McEleney

Weight


The Hyperion blows the competition out of the water in this category. Weighing only 19 ounces it’s half a pound lighter than its closest competitor. As we mentioned in the warmth section, the Therm-a-Rest Hyperion trades off some of its warmth for those extra ounces.

Therm-a-Rest Hyperion 20 sleeping bag womens - we like the hyperion's clever half-zip design; it reduces weight and...
We like the Hyperion's clever half-zip design; it reduces weight and helps stop drafts from getting through the zipper.
Credit: Ian McEleney

Comfort


Again, in an effort to slim down the ounces, the Hyperion has a trimmed down silhouette that makes for quite a snug fit. We tested the “Small” size and our 5’5 tester just barely fit length-wise. She was able to get the hood over her head and was quite cozy; however, we think most folks who aren’t used to a snug mummy fit will not feel comfortable in this bag. There is very little legroom (your legs are essentially pinned together in the bag), but there is an articulated foot box so your feet don’t feel squished. This bag is all about its low weight, and you sacrifice comfort noticeably for fewer ounces. We do think that this snug fit helps keep the warmth in. This bag also only has a half-length zip and some people will find this less comfortable as well.

Therm-a-Rest Hyperion 20 sleeping bag womens - the hyperion is a tight fit for our 5'5 tester and snug all the way...
The Hyperion is a tight fit for our 5'5 tester and snug all the way around the body and legs. The articulated foot box helps your feet feel more comfortable.
Credit: Ian McEleney

Packed Size


This bag packs down to a tiny little capsule and gets really small. We like that the Therm-a-Rest Hyperion comes with a compression sack to make it even smaller than a traditional stuff sack would.

Therm-a-Rest Hyperion 20 sleeping bag womens - the hyperion's packed size is tiny, as seen here next to a 1 liter...
The Hyperion's packed size is tiny, as seen here next to a 1 liter Nalgene bottle.
Credit: Jessica Haist

Features


The Hyperion’s features are all about weight savings, which we think is great. It has a really high quality down fill of 900, which increases its warmth to weight ratio, and the half-length zipper shaves a few grams. This bag also comes with “SynergyLink™ Connectors” that are essentially removable straps you can use to attach your bag to your sleeping pad if you’re one to roll off your sleeping pad. We really like that they’re removable and appreciate the simple attachment system.

Therm-a-Rest Hyperion 20 sleeping bag womens - the hyperion's sleeping pad straps are very small and lightweight.
The Hyperion's sleeping pad straps are very small and lightweight.
Credit: Jessica Haist

Value


Even though the Hyperion has high-quality materials, we think the price tag is a little steep. There are other products in this review that you get a lot more bang for your buck than with the Hyperion. However, it is one of the lightest bags we’ve found that’s sized for smaller people. If the conditions and mission are right, it could be worth the money for you.

Conclusion


The Therm-a-Rest Hyperion is a great choice for fast and light summer adventures. This is a very snug-fitting mummy-style bag that’s comfort rated to 32 F, so be sure you’re ready to sacrifice a bit of comfort and warmth for a tiny, lightweight package. If you’ll be spending lots of time carrying your stuff around, and don’t think the temperatures will go below freezing, this bag could be a great choice for you, if you’re willing to pay the price.

Therm-a-Rest Hyperion 20 sleeping bag womens - our favorite thing about the hyperion's sleeping pad attachment...
Our favorite thing about the Hyperion's sleeping pad attachment straps is that they're removable with an easy grommet.
Credit: Jessica Haist

Jessica Haist
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