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	Insulation Type	Materials
Boost 650 Sleeping Bag	Sleeping Bag	20F/-6C 32F/0C	650-Fill Nikwax Hydrophobic Down™	Shell: 20D Polyester w/ DWR Lining: 20D Polyester Taffeta
Corus™ Quilt	Camping Quilt	20F/-6C 32F/0C	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	Insulation Type	Materials
Vesper™ Quilt	Camping Quilt	20F/-6C or  32F/0C	900-fill Nikwax Hydrophobic Down™	10D Nylon Ripstop
Parsec™ Sleeping Bag	Sleeping Bag	0F/-18C or 20F/-6C	900-fill Nikwax Hydrophobic Down™	Recycled 20D Nylon Ripstop
Polar Ranger™ Sleeping Bag	Sleeping Bag	-20F/-30C	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. Consider 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, warmth, it turns out, is subjective. 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 how your body reacts at different temperatures will allow you to accurately use these temperature ratings, but that requires experience sleeping outside n a range of conditions. 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 include the consideration of fit. Buying a bag with too much room will make your body work harder to warm it up, and a bag or quilt that is too tight will result in compressed down and cold spots. 

Height

It doesn't have to be a tailored fit, but you should choose a bag or quilt that is as close to your actual height as possible allowing a bit of added room for maximum comfort while wearing layers and moving around inside the bag. To accommodate this, we offer two lengths in each: 

Quilts

Regular: 79 in/183 cm long (fits people up to 72 in/201 cm)

Long:     83 in/211cm long (fits people up to 78 in/198cm)

Sleeping Bags

Regular: 80 in/203 cm (fits people up to 72"/183 cm)

Long:      85 in/216 cm (fits people up to 78"/198 cm) 

Girth

While girth (a lateral measurement of the widest part of a sleeping bag's interior) is generally not a variable you can buy into, it's worth noting that the colder the rating of the sleeping bag, the larger its girth will likely be. We build extra room into our coldest bags because we know winter means added layers, boot liners, gear, and more are often inside the bag with you at night. Summer bags are narrower, reflecting a priority on lighter weight designs for warmer temperatures.

The Sleep System Philosophy

While everything around you is your sleep environment, everything that touches you while you sleep is part of your system. From your sleeping pad, sleeping bag or quilt, pillows, layers, etc., they all directly affect your warmth. Fortunately, this also means you have far more options for controlling your system's warmth than you might have thought. 

Let's take your summer sleep system for example. Maybe you have a 32F/0C Vesper Quilt and a NeoAir XLite NXT that keeps you happy as clam until it gets below 40F. At that point, you can toss on a hat and maybe some base layers, and you're good for another 10 degrees F. As fall approaches and you're waking up to frost on the ground, you could change out your sleeping pad to an XTherm, switch over to a Parsec 20F/-6C sleeping bag, or sleep in a few more layers to get you by. Colder still? Try layering your Vesper over your Parsec to get another 10 degrees or so of warmth out of your system and add a light down vest to your sleeping attire. 

The idea is that colder weather doesn't just leave you with a choice of a warmer sleeping bag. You can mix and match all the components of your system for incremental change while gaining greater versatility with fewer items across a wide range of conditions. Start thinking in terms of a sleep system, and you'll be more empowered to dial in the comfort you need.

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 sleeping pad's warmth, a quilt eliminates the bottom insulation, which is typically compromised by compression anyway. A quilt trades that wasted insulation for unparalleled freedom of movement and comfort in an ultralight, ultra-packable package. As part of a system, it is a game-changer. Most people who try them are hard-pressed to give them up.

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 shift that insulation to key areas on the top of the bag to provide more warmth without adding weight. Examples of key areas would be through the chest and torso section and the heat-trapping draft collar.

Zoned Insulation leans into 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 maximum insulation from your system.

Quilt Loops
Building a personalized sleep system offers a whole new level of versatility through 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, keeps them 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 we minimize the impact of our sleeping bags and pads is by using only 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 capable of making most repairs, and if we can't, we can likely connect you with a trusted vendor who 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.