REASONS TO BUY
Very lightweight
Small packed size
High-quality down
REASONS TO AVOID
Tight-fitting mummy bag
Not very warm
Expensive
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
We've spent hundreds of nights in the backcountry testing out these bags for you.
Credit: Ian McEleney
RELATED: Best Sleeping Bags for Women of 2024
Our Verdict
The Therm-a-Rest Hyperion 20 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 when 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 the price tag and niche use will give some people pause. Our full article on the top-rated women's sleeping bags will show you how the Hyperion fares versus competing products.
Compare to Similar Products
 This Product
Therm-a-Rest Hyperion 20 | |||||
|---|---|---|---|---|---|
| Awards |  Best Ultralight Sleeping Bag for Women |  Best Overall Women's Sleeping Bag |  Best Value for a Down Sleeping Bag | Best Value for a Synthetic Sleeping Bag | |
| Price | $550 List | $589 List $529.00 at Feathered Friends | $220 List | $169.00 at Backcountry Compare at 2 sellers | $125.93 at REI |
Overall Score  |
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| Star Rating | |||||
| Bottom Line | If you're willing to sacrifice a bit of warmth and comfort for this lightweight package, this could be the bag for you | The highest three-season performance of any model in our bunch | "Get Down" with this extremely well priced sleeping bag that will work for short to medium length backpacking trips in the summer | This synthetic model offers snug fitting design that is surprisingly compressible and a good choice to keep you warm in wet conditions | Too heavy and bulky for backpacking but a great choice for car camping comfort |
| Rating Categories | Therm-a-Rest Hyperi... | Feathered Friends E... | Sierra Designs Get... | The North Face Cat'... | Marmot Trestles Eli... |
| Warmth (25%) | |||||
| Weight (25%) | |||||
| Comfort (20%) | |||||
| Packed Size (15%) | |||||
| Features (15%) | |||||
| Specs | Therm-a-Rest Hyperi... | Feathered Friends E... | Sierra Designs Get... | The North Face Cat'... | Marmot Trestles Eli... |
| EN Temp Rating (Lower Limit) | 32°F | 20°F (not EN rated) | 23°F | 20°F | 20°F |
| Insulation | 900 FP Goose Nikwax Hydrophobic Down RDS | 950+ Goose Down | 550 FP DriDown RDS | Recycled synthetic | HL-ElixR synthetic fibers |
| Measured Weight | 1.19 lbs | 1.72 lbs | 2.36 lbs | 2.50 lbs | 2.75 lbs |
| Female-Specific Features | Available in a "Short" length, which is a standard women's size | Extra fill in footbox and chest | Women's specific cut | Available in a "Short" length, which is a standard women's size | Women's specific fit |
| Fill Weight | 12.0 oz | 17.3 oz (medium) | 25.0 oz | 38.9 oz | Unspecified |
| Material | 10D ripstop nylon w/ DWR | Pertex Endurance UL | 20D polyester | 20D ripstop nylon, taffeta | 20-denier recycled ripstop polyester |
| Neck Baffle | No | Yes | No | Yes | Yes |
| Small Organization Pocket | No | No | No | Yes | Yes |
| Sleeping Pad Sleeve | Removable attachment straps | No | No | No | No |
| Zipper Length | 35 in | 62 in | 39.5 in | 34.5 in | 53/15 in |
| Shoulder Girth | 55 in | 54 in | 58 in | 60 in | 58 in |
| Hip Girth | 48.5 in | 56 in | 56 in | 55 in | 58 in |
| Foot Girth | 36 in | 38 in | 40 in | 41 in | 45 in |
| Compression or Stuff Sack | Compression sack and storage bag | Stuff sack and storage bag | Stuff sack and storage bag | Compression sack and storage bag | Stuff sack and storage bag |
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Our Analysis and Test Results
The Therm-a-Rest Hyperion 20 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. You will sacrifice some creature comforts and warmth for the light weight, but for the right person and adventure, this could be a bonus.
Performance Comparison
The Hyperion is a great choice for trips when you need to go fast and light.
Credit: Ian McEleney
Warmth
Because the Hyperion is a unisex model, its temperature rating is different from the women's-specific bags in this review. Therm-a-Rest rates this bag to the EN “limit” rating, which in this case is 20°F versus the “comfort” rating of 32°F. This is different from the other women's specific bags we've tested, which use the “Comfort” rating in their naming conventions, but this seems to be the way that Therm-a-Rest rates all their bags. This is definitely something to note when you're comparing the Hyperion to other products in this review.
We took this bag out on a chilly September night, and we'd say the rating is just about right. As the temperatures dipped towards freezing in the wee hours of the morning, we felt chilly but never cold. Arguably, for our testers, the “limit” of this bag is 32 degrees. We like the half zip as it prevents drafts from coming through the zipper, and its snug hood does the same.
The Hyperion is a very snug-fitting bag, especially around the legs. This means that there is less cold air around your body that needs to get heated up, but it also means there is less room to put on extra layers. For broader-shouldered or hipped individuals, this may mean you can't put that extra layer of puffy pants or jacket on.
The Hyperion's snug hood helps keep warmth in, as does its tight-fitting silhouette.
Credit: Ian McEleney
Weight
The Hyperion is one of the lightest bags we tested. Therm-a-Rest shaved the ounces wherever they could.
As we mentioned in the warmth section, the Hyperion trades off some of its warmth for those extra ounces. Things that help contribute to the Hyperion's feather-lightness are… well, its feathers. The high-quality 900 fill power down means that this bag is a lot warmer per square ounce compared to other bags with lower quality down which is heavier and requires more to equal the same amount of warmth. We also like the clever half-zip that shaves a few more grams off the Hyperion's weight.
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 reduce the ounces, the Hyperion has a trimmed-down silhouette that makes for quite a snug fit. We tested a size small, 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 in the Hyperion (your legs are essentially pinned together in the bag), but there is an articulated foot box so your feet don't feel squished. The shoulder girth is an average of 3-8 inches narrower, and the hip girth is 6-10 inches narrower than most bags in this review. The Hyperion 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 — some people will find this less comfortable if they want to fully unzip when feeling warm or wanting to stretch out.
The women's size small Hyperion is a tight fit for our 5'5" tester and snug all the way around the body and legs. That said, the articulated foot box helps your feet feel more comfortable.
Credit: Ian McEleney
Packed Size
The Therm-a-Rest Hyperion packs down to a tiny little capsule and gets really small. We like that it comes with a compression sack to make it even smaller than a traditional stuff sack would.
This bag also comes with a larger storage sack so you can store it uncompressed. This is a best practice for any sleeping bag as it helps retain loftiness over time.
The Hyperion's packed size is tiny, as seen here next to a 1 liter Nalgene bottle.
Credit: Jessica Haist
Features
The features of the Hyperion are all about weight savings, which we think is great. This bag 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.
The Hyperion also comes with “SynergyLink Connectors” which 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 in the night. We really like that they're removable and appreciate the simple attachment system — this is the best pad attachment system we've tested because it's so minimal and light. Another weight-saving feature is the Hyperion's tiny gauge zipper — although it does not have an anti-snag feature like many other products in this review.
The Hyperion's sleeping pad straps are very small and lightweight.
Credit: Jessica Haist
Should You Buy the Therm-a-Rest Hyperion 20?
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 offer a lot more bang for the buck. However, the Hyperion 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. We love this bag for fast and light summer adventures, though keep in mind that the snug-fitting mummy style can feel constricting. Still, if you'll be spending lots of time carrying your stuff around, trying to move fast and cover lots of ground, and don't think the temperatures will go below freezing, this bag could be a great choice.
What Other Sleeping Bags Should You Consider?
If price isn't as much of an issue, our favorite overall sleeping bag is the Feathered Friends Egret UL 20. With good care, this bag will easily last you a decade or more. Finally, if you want to avoid down and also save major bucks, the The North Face Cat's Meow is an easy and classic choice.
—
Jessica Haist
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