A great night's rest is the foundation of every adventure. That makes your sleeping bag or quilt one of the most important pieces of equipment in your kit, and the question of how to choose the right one is a big one.

With that in mind, we put together this guide to choosing the best sleeping bag or camping quilt to build your ideal sleep system for any adventure. The aim is to help you understand how and why the designs of our bags—their feature sets, technologies, and specifications—are suited to different types of sleepers and adventures. We will first do a run-through of our lineup, then dive into a discussion of features, technologies, and important considerations.

Therm-a-Rest's Lineup

Our sleeping bags and camping quilts are organized into two categories: Fast & Light and Backpacking Comfort. (Our sleeping pads use the same organization, but add an additional category called Camp & Comfort). Across these two categories, you will find true ultralight specialists, seasonal experts, quiver killers, and, ultimately, a bag or quilt that will keep you warm and comfortable just about anywhere on earth.

Backpacking Comfort Sleeping Bags & Quilts

Backpacking Comfort is all about versatility and usability. It is our line of gear that merges high-performance and lightweight design with a comfort-conscious, utilitarian philosophy. These feature-rich sleeping bags & quilts are light enough for backpacking and comfortable enough for car camping.

Series	Type	Models	Fit	Insulation Type	Materials
Boost 650 Sleeping Bag	Sleeping Bag	20F/-6C 32F/0C	Warm Zip™ Tech Adjustable Volume	650-Fill Nikwax Hydrophobic Down™	Shell: 20D Polyester w/ DWR Lining: 20D Polyester Taffeta
Corus™ Quilt	Camping Quilt	20F/-6C 32F/0C	Single	650-fill Nikwax Hydrophobic Down™	Shell: 20D Polyester w/ DWR Lining: 20D Polyester Taffeta

Boost 650™ Sleeping Bags

Available in 20F/-6C and 32F/0C temperature ratings

Best For: Backpacking, car camping, couch surfing; you name it! People looking for one bag to do it all.

If you prioritize comfort and versatility in a sleeping bag, we created the all-new Boost 650 bags just for you. Featuring our new WarmZip Tech, these bags can go from car camping to the backcountry and everywhere in between, all with the slide of the midline zipper, allowing you to go from a roomy, cooler semi-rectangular shape to a warmer (up to 10F!), more streamlined mummy-style shape on colder nights. Zippered arm holes make accessing the WarmZip (or anything else nearby) a cinch, and provide added ventilation for, you guessed it, greater versatility and comfort across a range of temperatures.  The Boost 650 sleeping bags are also available in Short, Regular, Long, and Wide sizes to ensure a great fit for every body.

Corus™ Quilts

Available in 20F/-6C and 32F/0C temperature ratings

Best For: Backpacking, car camping, paddling, bike packing, layering.

If you've not tried a quilt, you need to, and the Corus is a great place to start.  In its temperature range, the Corus offers an unbelievably comfortable and lightweight alternative to a sleeping bag. When temperatures drop, layer it with another or over your sleeping bag, and you can extend your 3-season bag well into winter. Though not the lightest quilt we make, the added width—especially in the footbox—allows the Corus to perfectly adapt to comfort-conscious car camping. If you are looking to add versatile performance to your sleep system at a friendly price, look no further.

Fast & Light Sleeping Bags & Quilts

The sleeping bags and quilts in this category are purpose-driven. That purpose? Ultralight, super-compact, high-performance sleep systems. Made of the highest-quality materials and engineered for efficient comfort, our Fast & Light sleeping bags and camping quilts can be relied on for uncompromising backcountry performance time and time again.

Series	Type	Models	Fit	Insulation Type	Materials
Vesper™ Quilt	Camping Quilt	20F/-6C or  32F/0C	Single	900-fill Nikwax Hydrophobic Down™	10D Nylon Ripstop
Parsec™ Sleeping Bag	Sleeping Bag	0F/-18C or 20F/-6C	Performance Fit	900-fill Nikwax Hydrophobic Down™	Recycled 20D Nylon Ripstop
Polar Ranger™ Sleeping Bag	Sleeping Bag	-20F/-30C	Performance Fit	800-fill Nikwax Hydrophobic Down™	Recycled 20D Nylon Ripstop, DWR

Vesper™ Quilt

Available in 20F/-6C and 32F/0C temperature ratings

Best For: Ultralight pursuits, thru-hiking, mountaineering, backpacking, paddling, bike packing, layering.

If gram-shaving is what gets you up in the morning, and keeps you up at night, this is the quilt for you. As with all of our quilts, you'll enjoy unparalleled freedom of movement and a lot less weight and bulk in your pack. Our finest 900-fill hydrophobic down delivers the warmth (and a tiny packed size), while SynergyLink™ Connectors keep the quilt anchored to your sleeping pad so you stay under it all night long. Side baffles keep drafts at bay, and an enclosed footbox and box-baffle construction make sure cold spots are never a thing. 

Parsec™ Sleeping Bag

Available in 20F/-6C and 0F/-18C temperature ratings

Best For: Ultralight pursuits, backpacking, paddling, bike packing, sleeping anywhere you want.

The Parsec is our go-to bag for those who demand the most versatility from their sleeping bag. It delivers the ultralight performance you need for demanding backcountry trips and the comfort you want for a weekend of roadside cragging with friends. Built for speed, it features 900-fill hydrophobic down and a 3/4-length zipper, while zoned insulation ensures every ounce of down is maximized.

Polar Ranger™ -20F/-30F Sleeping Bag

Best For: The dead of winter and the coldest places on earth.

Have you ever heard the gunfire-like sound of trees popping, or the ice on a frozen lake moaning in extreme cold?  If you like being out all night in that kind of cold, the Polar Ranger is your sleeping bag. Working with one of the most accomplished polar explorers on the planet, Eric Larsen, we designed this bag for maximum warmth on expeditions to the world's coldest places. Features like the side vents that allow arm use outside of the bag without unzipping it, along with a draft-blocking snorkel hood and massive amounts of down, make it a highly specialized sleeping bag. However, if you need it, there's nothing that beats it. 

Temperature Ranges

We have been industry leaders in standardizing warmth ratings for our products and have adopted the latest EN/ISO protocols to rate the warmth of our sleeping bags and quilts. Let's take a look at how that works.

When shopping for a sleeping bag or quilt, you'll find that each one has a designated temperature rating. When considering a bag rated 20F/-6C, for example, the temptation is to assume it will keep the sleeper warm at 20F/-6C no matter what. While this may be true in many cases, overnight warmth is more complex. This is why the EN/ISO standard breaks the rating into three conceptual temperature ranges: Comfort Range, Transition Range, Risk Range.

Comfort Range
A sleeper should feel warm in the bag or quilt in these conditions.

Transition Range
The official listed temperature rating (e.g. 20F/-6C) is the bottom limit of this range. Somewhere in this range is the performance limit of the bag for most people. A warm sleeper might feel comfortable while a cold sleeper may be fighting against the cold.

Risk Range
Beyond the performance limit of the bag or quilt. Sleeping in these conditions is dangerous. It is not recommended unless it’s an emergency.

Know How You Sleep

We believe that an informed customer is empowered to make the right gear decisions, resulting in many safe nights under the stars. That said, it is important to keep in mind that sleeping bag and quilt temperature ratings are just a piece of the puzzle. The R-value of your sleeping pad, base layers, your diet and other factors all affect sleep warmth.

Knowing what kind of sleeper you are will allow you to most accurately use the temperature ratings, but that requires experience sleeping outside. If you’re here shopping for your first bag or quilt in order to gain that knowledge, a great starting point is to consider what conditions you'll be sleeping in MOST of the time. If you're a summer backpacker at lower elevations, a 45F/7C quilt might be the perfect thing for you. However, if you venture into the alpine frequently, or like to extend your season into the fall where freezing nights are the norm, a 20F/-6C bag might be a better choice. At some point, if you like year-round camping, you'll need more than one solution to keep you comfortable year-round, but aiming for that "most of the time" bag is a great place to start.

Insulation Type

There are two types of insulation in sleeping bags and quilts, down and synthetic. Both have certain benefits and certain drawbacks, but down is the clear winner when talking about high performance warmth.

Down Insulation
Down is the soft, fluffy plumage found under the exterior feathers of a bird. It is almost always harvested from waterfowl because they produce a lot of it to insulate from cold water. At Therm-a-Rest we only use Responsible Down Standard (RDS) certified down.

Here are some quick hits on down insulation:

Therm-a-Rest does a lot to mitigate that first drawback by using hydrophobic down in our sleeping bags and quilts. While synthetic insulation is still better on the rare occasion that your bag gets wet, hydrophobic down performs 90% better than untreated down when wet. If you are adventuring in wet forecasts but still want the warmth-to-weight performance of down, treated down is the way to go.

Other than that, down is the clear winner over synthetic for sleeping bags because of its vastly superior compressibility and light weight. 

Synthetic Insulation
Synthetic insulation is the human attempt to mimic naturally occurring down with synthetic fibers. While it is true that synthetic bags retain some insulating value when wet, there are few other benefits beyond price.  They are much heavier and larger than down bags and simply not the best choice when you're carrying your sleeping bag for miles. 

Here are some quick hits on synthetic insulation:

 While not ideal for sleeping bags, synthetic is still the most functional choice for wearable insulation pieces, like our Honcho Poncho when you might be throwing on your amazing insulated poncho after a hot spring soak on a cold night, or spilling food into your lap at a campfire. 

Even with hydrophobic down, one should avoid getting their down sleeping bag or quilt wet. Down feathers escape through any tears or small holes, whereas synthetic does not. Down can also clump up if not dried carefully after washing, though that is relatively easy to undo.

We highly recommend reading our guide to washing sleeping bags, becuase proper care and storage are essential for maintaining their peak performance. 

Sleeping Bag & Quilt Fit

The question of how to choose a sleeping bag or quilt should always include the consideration of fit.

When we say "fit", we mean more than just small, medium, and large, though size is a component of choosing the right fit. Moreover, it is important to note that all of our bags and quilts are unisex. Regardless of your sex, just go with the size that is most appropriate for your height.

Here’s a breakdown of size-to-height correlations:

• Small: 5’1” – 5’6” (156 cm – 168 cm)
• Regular: 5’7” – 6’0” (170 cm – 183 cm)
• Long: 6’1” – 6’6” (185 cm – 198 cm)

Having the wrong size bag or quilt will affect thermal efficiency. If it is too large, your body will have to expend more energy to heat the excess internal space, or not be able to heat it at all, resulting in a cold night. If it’s too small, you risk not properly covering your body and creating cold spots where the insulation is compressed.

While choosing the right size is objective based on your height, picking the right fit profile is subjective and depends on your preferences. By “fit profile,” we are essentially referring to the internal shape of the bag or quilt. (By contrast, external shape refers to the style: mummy, rectangular, semi-rectangular).

Our sleeping bags and quilts come in three different fit profiles: Ultralight Fit, Performance Fit, and W.A.R.M. Fit. Each is tailored to different types of adventurers and sleepers.

Ultralight Fit

As the name suggests, this fit is all about trimming weight and compact packing. Bags and quilts with this fit are specialized pieces of gear. They are narrower throughout the shoulders, hips and footbox. Less internal space means less energy required to heat it, as well as less energy expended to carry it. It also means less room to move around and get comfy at night.

If you are all about ultralight packs for fast backcountry travel, and willing to sacrifice some comfort for it, Ultralight Fit is optimized for you. If you are a side sleeper you may feel confined in one of these bags.

Performance Fit

Like Ultralight Fit, the bags and quilts with Performance Fit are only in our Fast & Light category. The point is to provide ultralight options to sleeper profiles that require more space for better rest. Examples would be side sleepers or cold sleepers that may be donning extra layers—like a puffy jacket—for overnight warmth. The extra internal space may add grams, but that is justified price to pay if it means you will be better rested.

These bags and quilts are still compact, lightweight and altogether designed for the backcountry. Still, with a touch more room for comfort a Performance Fit piece will be better suited for weekends in the crag parking lot or general car camping than Ultralight Fit bags and quilts. If you are a comfort-conscious thru-hiker, or a backcountry traveler that knows your trip schedule includes car camping as well, performance fit is an excellent option.

W.A.R.M. Fit

With Additional Room for Multiple Positions. It may be an imperfect acronym, but we really want you to know that the extra room in these bags and quilts DOES NOT result in cold spots (we’ll explain why in a moment). Continuing up the spectrum from Performance Fit, W.A.R.M. bags and quilts comprise the Trek & Travel line.

The concept is to offer backcountry ready sleeping bags and quilts that allow a wide range of natural sleep positions. The point of a sleeping bag or quilt (really the point of our whole company) is to achieve quality nighttime rest in the outdoors. If you are a side sleeper, an active dreamer, or a position pluralist a narrow sleeping bag can be really frustrating (or downright claustrophobic) and rob you of good, solid sleep.

W.A.R.M. Fit bags are great for backcountry travelers that move around in their sleep, or are otherwise uncomfortably confined by narrow bags, and willing to add some weight for better sleep. What’s more, these bags and quilts are well suited for frontcountry adventures. When weight and packed size are of lesser concern, why not prioritize comfort? If your adventure calendar has you backpacking deep into the wilderness but also spending quality time car camping with friends, W.A.R.M. Fit is a strong choice for you.

The Sleep System Design Philosophy
But what about cold spots? Good question, here’s the answer: The reason we are able to offer spacious W.A.R.M. Fit bags and quilts that are light enough for backcountry use and still thermally efficient, comes down to a series of design choices and features that lean into the concept of a sleep system. It is about maximizing the strengths of each system component as efficiently as possible.

It is not just our W.A.R.M. fit bags that incorporate this design philosophy. All of our fits and models are informed by building them to be components of a system. The easiest way to understand what this means is by understanding what makes camp quilts so special.

The Quilt Revolution
Quilts are much lighter and more compact than sleeping bags because they are, more or less, half a sleeping bag. By relying on the warmth of the sleeping pad, a quilt does away with the insulation on the bottom, which is typically compromised by compression anyway, and exchanges it for unparallelled freedom of movement. As a part of a system, it is a game changer.

We mapped that concept, of reducing reliance on down that you're sleeping on and compressing, onto our sleeping bag line to create lighter, more comfortable bags that don’t sacrifice performance. Here are the specific features that get it done.

Zoned Insulation
Zoned Insulation is the prioritization of insulation to the areas of the bag or quilt where your body needs it most.

Insulation on the bottom of a sleeping bag becomes compressed under the weight of your body. This results in fewer air pockets and a significant decline in its insulating ability. So, we reduce the amount of insulation on the bottom accordingly, which saves weight and gives us the option of adding more insulation to key areas on the top of the bag without adding weight. Examples of key areas would be through the chest and torso section and the heat-trapping draft collar.

Zoned Insulation relies on the R-Value of your sleeping pad to provide warmth, so choosing the right pad to go under your bag or quilt is an important consideration. Thinking holistically about your sleep system opens up the door to mixing and matching sleeping pads, bags and quilts for the warmth you need in a broad range of conditions. 

SynergyLink Connectors
Have you ever woken up with your bag upside down, your face looking squarely into your hood, wondering where your zipper is? Stopping this panic-inducing chaos is the sole mission of our SynergyLink Connectors. These optional straps, attached to our bags and quilts, wrap around your sleeping pad, keeping your insulation right where you want it, without constricting your movement. They also reduce drafts, ensuring you get the maximum amount of insulation from your system.

Quilt Loops
Building a personalized sleep system offers a whole new level of versatility through the principle of layering.  Many of our sleeping bags have built-in quilt and blanket loops along each side of the bag for securing one of our quilts or blankets to the top of your bag in order to boost warmth. On cold nights, a securely integrated quilt can mean the difference between sleep-defeating cold spots and a comfy, thermally efficient night.

Footboxes
Therm-a-Rest quilts have thoughtfully shaped footboxes to ensure a secure fit all night long. On the Corus, the footbox is roomy enough to tuck the end of an XLite pad in. On the narrower Vesper, the footbox offers a snug, fast-warming pocket for your feet. If you are layering over a sleeping bag, the quilt footboxes will easily fit around it.

All of our sleeping bags also feature a Toe-asis™ Foot Warmer Pocket. This delightfully luxurious pocket just for your feet ensures they are warm, toasty, and not forgotten. Though not really a feature dependent on the sleep system design philosophy, the Toe-asis adds revelatory comfort to our bags without adding significant weight. The goal of a sleep system is high-performance rest, and our little foot pocket fits the description.

Regarding Environmental Impact

Lastly, when you ask yourself how to choose a sleeping bag, we hope you factor in its environmental impact. A point of contention in outdoor gear manufacturing is the difficulty in reducing negative environmental impacts in the supply chain. The simple truth you should know as a customer is that high-performance materials can be environmentally demanding.

That said, we are constantly working to improve our supply chains and reduce our environmental impact so that high performance doesn’t come at a high cost to the natural world.

One way that we minimize the impact of our sleeping bags and pads is by only using RDS-certified down. (Responsible Down Standard) RDS is a voluntary standard that ensures the waterfowl that supply our down are treated humanely. There is no requirement for us (or anybody else) to adhere to this standard, but it is an obvious choice for us to do so.

Another essential environmental consideration is the lifespan of your gear. Blown-out and damaged gear heading to the landfill is something we make a great effort to avoid. Since 1972, our products have only been made with the finest materials, with a central focus on durability and repairability. Our sleeping bags and camping quilts demonstrate the legendary, long-lasting build quality for which we are known.

Our gear is made to last, yes, but it is also made to be used. We want you tucking into your sleeping bag or quilt for as many nights under the stars as you can muster. Damages happen. Zippers get caught, tears spring up, down leaks, etc. When this happens, there’s no need to buy a new bag. We have a full-service repair facility, fully capable of making most repairs and, if we can't, we can likely connect you to a trusted partner that can. That way you can keep the gear you know and trust out of the landfill and in your backpack.

 Thank you for reading, if you have any thoughts please leave us a comment or get in touch!

Related Posts:

• How to Choose the Right Sleeping Bag Size, Shape & Fit
• Down vs. Synthetic Sleeping Bags & Quilts Insulation
• 3-Season Sleeping Bags vs. Winter Sleeping Bags

Updated. Originally Published December 3, 2020.