The best sleeping bags

The right (or wrong) sleeping bag has the ability to make or break a backpacking or camping trip. If you choose the wrong one, you’ll have a long and restless night but if you do your research and pick the best bag for your target destination, you’ll sleep as soundly in a shelter as you do at home.

Therm-a-rest Hyperion 20

The best ultralight

Why should you buy this: The Hyperion is incredibly warm for its weight.

Who’s it for: Backpackers who want warmth in a featherlight bag.

Temperature rating: 20 degrees Fahrenheit

Weight: 1 pound, 4 ounces

Fill: 13 ounces of 900 Fill Goose NHD/RDS

Why we picked the Therm-a-Rest Hyperion 20:

The Therm-a-Rest Hyperion is so light in weight you won’t believe it’ll keep you warm, but it will. Its incredible lightness and warmth comes from the premium 900 fill goose down that is packed into the well-placed baffles. You get plenty of loft from the 900 fill down making the bag as comfy as it is cozy. The down is smartly distributed with 70 percent of the loft on the top of the bag where you need it the most and 30 percent underneath you. Be warned, the Hyperion is so comfy that you’ll want to climb into it each night and not get out.

Our two favorite features are the long zipper and the sleeping pad straps. The three-quarter length zipper allows you to cool off quickly when you overheat — just unzip as needed. In warmer weather, you can even use the bag on top of you like a quilt. You can’t unzip it fully like a rectangular bag, but you can stick your feet in the closed foot box and drape the unzipped bag across your legs and torso. The sleeping pads straps are a bonus feature not seen on many other sleeping bags. They hold the sleeping pad securely to your bag so you don’t slip off and end up on the hard, cold ground. These straps are a godsend for the restless sleeper, but they can be removed if you don’t want them.

The Hyperion has a mummy cut so it can be snug around the shoulders for larger individuals. The regular bag measures 57 inches across the shoulders, 49.5 inches across the hips, and 43 inches in the footbox.  The Hyperion is rated down to 20 degrees if you have the right base layers for sleeping but it is most comfortable at 32 degrees or warmer. It’s plenty warm enough for three-season usage — possibly even four seasons if you consider yourself a warm sleeper or don’t travel in extreme conditions. It also is available in a 32-degree version that weighs an incredible 16 ounces. For fair weather hiking, the 32 degree Hyperion is an outstanding bag for lightweight or long-distance hikers.

REI Co-Op Magma 15

The best three-season down sleeping bag

Why should you buy this: The Magma 15 from REI offers a winning combination of quality design, outstanding warmth, and reasonable cost.

Who’s it for: The Magma 15 is for backpackers who place a priority on warmth when it comes to sleeping.

Temperature rating: 16 degrees Fahrenheit

Weight: 2 pounds

Fill: 16 ounces of 850 fill DWR-treated goose down

Why we picked the REI Co-Op Magma 15:

The REI Magma may not have snazzy features like self-closing toe boxes but the bag hits the mark where it matters most — comfort and warmth. The lightweight Magma has an inner 15D nylon lining that is soft to the skin and an outer 15D Pertex shell that resists tearing and repels moisture. It has enough space in the toe box to move your feet and is roomy enough in the hood to fit a small backpacking pillow for a good night’s sleep. The bag has a fitted mummy cut that trims weight and a variable baffle design that deliver warmth. Most people won’t mind the trim fit, but broad-shouldered people may find it a bit snug.

The Magma 15 has a temperature range that makes it a solid three-season bag suitable for spring, summer, and fall in the mountains. When temperatures plummet, there are two drawstrings on the hood that provide a snug fit while an insulated draft collar and a draft tube on the zipper help to trap body heat inside the bag. To let off some heat, the bag can be unzipped in an arc across the shoulders. When conditions warm up, the bag can be fully unzipped and used as a quilt. An internal anti-snag strip makes it easy to open the bag from both inside and outside the bag without catching on the fabric. The new-for-2019 Magma 15 is available in both a men’s and women’s version. For wamer climates, there is a 30-degree Magma sleeping bag and a quilt.

Big Agnes Bolten SL 20

The best three-season synthetic sleeping bag

Why should you buy this: Backpackers who want all-weather protection should look at the Big Agnes Bolten SL 20, which is crafted with a durable and lightweight synthetic insulation that stays warm even when it’s wet outside.

Who’s it for: Backpackers and car campers who explore in areas where wetness is a major concern.

Temperature rating: 20 degrees Fahrenheit

Weight: 2 pounds 11 ounces

Fill: PrimaLoft Silver & PrimaLoft Gold Active stretch insulation

Why we picked Big Agnes Bolten SL 20:

There is little argument that a down sleeping bag is warm — it’s perhaps the warmest material you can wrap yourself in. However, down insulation does have a significant flaw — it loses its warmth when wet. Manufacturers have turned to a special water-resistant down that is treated superficially with a DWR-like Nikwax but this technology is relatively new and its effect on the longevity of a down bag is unknown.

While many sleeping bag makers use down in their high-end bags, manufacturers like Big Agnes realize there is a huge market for synthetic fabrics, as well. These synthetic bags offer a significant advantage because they stay warm even while wet, though wet warmth does come at a cost as synthetic bags are often heavier and bulkier. This is where the Big Agnes Bolten SL 20 shines by offering the wet warmth advantage of synthetic insulation while maintaining a lightweight profile that rivals many down bags in the same temperature class.

So, how does the Big Agnes manage to make a synthetic bag almost as light as down? The answer lies in the materials. The company uses PrimaLoft Silver and combines it with PrimaLoft Gold Active stretch insulation. Primaloft has spent decades perfecting its insulation so it mimics down with millions of air pockets that trap your body heat. The result is a lightweight insulation that’s warm, durable, and compressible. The active stretch insulation is a unique addition to the bag. It’s built into side stretch panels that provide some give in the sleeping bag allowing you to sleep on your side and move around inside your bag.

The Big Agnes Bolten screams comfort with a top zipper that is easy to undo and extends almost the full length of the bag. When unzipped, the bag can be used as a quilt for sleeping in warmer weather. Other features include interior fabric loops for sleeping bag liners, exterior loops for easy drying, and an integrated draft tube to prevent snags and minimize cold air from seeping in through the zipper.

Big Agnes Lost Dog 15

The most eco-friendly

Why should you buy this: The Lost Dog 15 is warm, comfy, and easy on the environment.

Who’s it for: Backpackers who want a warm sleeping bag made from recyclable materials.

Temperature rating: 15 degrees Fahrenheit

Weight: 3 pounds, 3 ounces

Fill: 31 ounces of FireLine™ ECO Synthetic Insulation

Why we picked the Big Agnes Lost Dog 15:

The Lost Dog 15 from Big Agnes shows that you can make a piece of gear from recycled materials and not sacrifice quality. The company’s latest three-season sleeping bag, the Lost Dog 15, is constructed with 100 percent recycled FireLine ECO Synthetic Insulation. This super warm synthetic and recycled polyester insulation is constructed to have an excellent loft, high compressibility, and an outstanding weight-to-warmth ratio. Whether you are in a tent or cowboy camping, the Lost Dog 15 will keep you warm down to 15 degrees Fahrenheit. It also is available in a 30-degree and a 45-degree version for warmer weather and a 0-degree bag for winter.

The bag is packed full of features both big and small. Our favorite feature is the flex pad sleeve which is designed to fit over almost any sleeping pad and hold it securely in place. No matter how much you toss and turn, you will stay securely on your sleeping pad. The bag has a free-range footbox for wiggle room and a free-range hood that allows you to lift your head without getting tangled up in the bag. On the inside of the bag, there is a jacket-style hood that securely lines your face and a draft-free zipper for a snug, warm fit.

The Lost Dog 15 is part of a growing trend of sustainability among manufacturers, and it is a movement that we are happy to see.

Therm-a-Rest Vesper Down Quilt 20

The best quilt

Why should you buy this: The Vesper quilt weighs less than a pound and is incredibly warm for its weight.

Who’s it for: Backpackers who want warmth in a featherlight quilt.

Temperature rating: 20 degrees Fahrenheit

Weight: 19 ounces

Fill: 12 ounces of 900-fill-power Nikwax Hydrophobic down

Why we picked the Therm-a-Rest Vesper 20:

The Therm-a-Rest Vesper quilt is incredibly light, just like its cousin the Hyperion sleeping bag which made it to the top of our list. Both the Hyperion and the Vesper owe their remarkable lightness and warmth to the premium 900 fill goose down used for insulation The quilt used the box baffled construction with mesh walls to ensure maximum loft and even distribution of down. For the sleeper, this means you’ll enjoy maximum comfort and no cold spots.

The outstanding feature of the Vesper quilt is its packability. It packs down to 5.5 x 8 inches (2.8L), allowing you to stuff it easily into a 5L compression sack. Pair the Vesper with Therm-a-Rest’s new Uberlite sleeping pad and you can fit both into a 10L sack. The quilt takes up barely any space in your pack allowing you to travel lighter and with a smaller backpack.

Like most Therm-a-Rest sleeping bags, the Vesper quilt includes a single sleeping pad strap. This SynergyLink Connector holds the sleeping pad securely to your bag so you don’t slip off and end up on the hard, cold ground. The straps is a must-have for the restless sleeper, but it can be removed if you are trimming ounces. Just keep track of the strap as it is easy to lose.

The Vesper has a mummy cut that is open at the top and a sealed footbox. There is no zipper, but the quilt does have a snap at the top that you can use to close the quilt around you like a sleeping bag. This design is not as air-tight as a sleeping bag, but the side baffles and top snap does help to reduce drafts. You want the flexibility of sleeping with just a blanket on top of you when it is warm and the ability to snuggle in the quilt when temps are colder. The Vesper quilt was tested down to its 20-degrees Fahrenheit limit, but we recommend it for warmer temps that are at least above freezing unless you want to wear a few extra layers to bed.

The Vesper quilt also is available in a 32-degree version that weighs a mere 15 ounces and packs down equally as small as its 20-degree counterpart.

Kelty Sine 35

The best warm weather sleeping bag

Why should you buy this: The Kelty Sine 35 is the perfect 3-season bag. It’ll keep you warm in the spring and fall but is designed with exceptional ventilation to cool you off when temperatures start to climb.

Who’s it for: Backpackers who want a single bag for the summer that’s warm enough for those unexpected cold nights.

Temperature rating: 35 degrees Fahrenheit

Weight: 1 pound, 14 ounces

Fill: 9 ounces of 800 fill power DriDown

Why we picked the Kelty Sine 35:

The Kelty Sine 35 is fantastic down bag for those warm summer hikes that take you to distant mountains. The bag’s number one feature is its flexibility as it’s ideal for both warm and colder nights, allowing you to pick one bag for 90 percent of your backpacking needs. It also accommodates a man-sized frame but has extra down for women who sleep cold.

As its name implies, the Sine 35 has a 35-degree rating when fully zipped — perfect for those occasional cold nights. When it gets warmer, the bag uses two well-placed zippers for ventilation; one which extends across the chest allowing for airflow and another that exposes the feet and lower legs, providing a way for cool air to seep into the bag without comprising warmth in the middle.

The Sine 35 is chock full of features. The Arc zipper system not only allows for cooling as mentioned above but it’s also set at an angle, allowing for natural arm movement across the body when unzipping the bag. There’s a natural fit toe box for comfort along with a zipper draft tube for warmth. Kelty designed the tube to be anti-snag, so you won’t need to worry about catching any fabric. Another bonus in the Sine 35 is the built-in pillow pocket at the head which allows you to stuff an extra jacket to create a pillow.

Sierra Designs Nitro 800/20 degree

The best shoulder season sleeping bag

Why should you buy this: The Nitro 800 keeps you warm and won’t weigh you down.

Who’s it for: Anyone who plans to sleep outside, whether they’re camping or backpacking.

Temperature rating: 20 degrees Fahrenheit

Weight: 1 pound, 12 ounces

Fill: 14.7 ounces of 800 fill PFC-free Dridown

Why we picked the Sierra Designs Nitro 800:

The Nitro 800 is the epitome of quality and value making it our top choice. Every aspect of the bag is designed to be just what you need without anything extra. The bag offers 14-ounces of high quality, PFC-free 800 fill goose down which keeps the weight down without inflating the cost. The Nitro 800 isn’t the lightest bag on the market, but its 1 pound and 12 ounces weight is still very packable for short and long trips. This weight is even more impressive when you climb inside the bag and realize how roomy it is — 62 inches for the shoulders, 56 inches for the waist, and 40 inches for the feet. Not too big, not too snug, the fit is just right.

Sierra Designs didn’t skimp on the construction and materials used in the bag. The company opted for a 15D nylon shell that doesn’t add a lot of extra weight but is durable enough that you don’t have to be overly gentle with the bag. There’s a rugged YKK zipper but it only extends about halfway down the bag. It’s easy to get in and out of the bag, but you can’t use it as a quilt. The bag has an efficient anti-snag zipper guard and a basic draft collar for warmth. It also has 5-inch baffles which help keep the down evenly distributed.

The Nitro has a roomy foot box that keeps your feet warm. To shed extra heat, the Nitro has a self-closing, zipperless foot vent that you can open when you need some extra ventilation. Just stick your feet through the vent when you are overheating and pull them back in when you have cooled down. When not in use, the vent closes snugly without any cold drafts.

The Nitro 800 20 is an all-around versatile bag. It’s well-ventilated for summer use in temperate climates and is warm enough for the shoulder season when temperatures start to drop. You may be able to eek out some winter trips with the right base layers. It also is available in a 0-degree and a 35-degree version for those who want a bag that is geared towards consistently colder or warmer conditions. Sierra Designs also developed women-specific versions of the Nitro 800/20 degree and the Nitro 800/0 degree.

Sierra Designs Cloud 800/20  Sleeping Bag

The best zipperless sleeping bag

Why should you buy this: Sierra Designs did away with zippers in the Cloud 800, and the result is a bag that’s lightweight and low maintenance.

Who’s it for: Minimalists who don’t want the fuss of zippers.

Temperature rating: 20 degrees Fahrenheit

Weight: 1 pound, 13 ounces

Fill: 14.8 ounces of 800 fill PFC-Free DriDown

Why we picked the Sierra Designs Cloud 800:

The Cloud 800 from Sierra Designs is a minimalist’s dream. The lightweight bag is simple in construction with a traditional mummy shape and zipperless design. Only the top portion of the bag opens and is secured using a crescent-shaped opening that uses tension to keep it shut. There’s also an inner comforter layer with a pocket that you can wrap around your shoulder to minimize drafts.

Other standard features of the Cloud 800 include a cinch hood and a roomy foot box with a self-sealing vent to let off heat. On the outside, the bag is covered in water-repellent, lightweight 15D ripstop nylon, while the inside of the bag is lined with a similar ripstop minus the extra waterproofing. There is even an integrated half pad sleeve designed to hold a sleeping pad that will cover all the pressure points on your hips, shoulders, and head.

Patagonia Hybrid Sleeping Bag

The best sleeping bag for alpine pursuits

Why should you buy this: The Patagonia Hybrid sleeping bag is the bag you want when weight matters on an alpine trek.

Who’s it for: Alpine Backpackers or mountaineers who already travel with a down parka and want a warm sleeping bag that weighs next to nothing.

Temperature rating: Varies based on layering

Weight: 1 pound, 1 ounce

Fill: 850-fill Traceable European down

Why we picked the Patagonia Hybrid sleeping bag:

The Patagonia hybrid sleeping bag does away with unnecessary weight by using an “Elephant’s Foot” design. This style of bag concentrates the insulation in the lower half of the torso, requiring the user to wear a warm down coat as insulation for the upper half of their body. This style of sleeping bag tends to be light and compact, making them suitable for alpine pursuits where ounces are critical.

Everything about the Patagonia hybrid bag is ultralight from the Pertex Quantum outer shell to the featherweight nylon ripstop liner. Both the outer and inner surface of the bag has a DWR finish which helps keep the down insulation (and its owner) dry. Unlike other “Elephant’s Foot” bags that are shorter in length, the Patagonia hybrid bag is a full-length bag with insulation at the bottom and a nylon upper with a cinch hood at the top to keep in the heat.

Besides being light and simple in design, the hybrid bag from Patagonia also is versatile. Because you’ll pair the sleeping bag with an insulated jacket, Patagonia allows for the customization of the sleep system to fit your needs. On a cold night, the bag might pair with a heavily-insulated down parka, while on a warmer night, the bag goes perfectly with a lightweight parka and no additional layers.

Mountain Hardwear Bozeman Adjustable Sleeping Bag

The best sleeping bag for kids

Why should you buy this: The Mountain Hardwear Bozeman is the perfect sleeping bag for kids — its unique design allows the bag to grow along with a child.

Who’s it for: Young children who love the outdoors

Temperature rating: 20 degrees Fahrenheit

Weight: 2 pounds, 4 ounces

Fill: Synthetic Thermal.Q Thermic MX

Why we picked the Mountain Hardwear Bozeman Adjustable sleeping bag:

Sleeping bags for kids are a difficult niche to fill. Quality bags tend to be quite expensive as they are designed with longevity in mind. Unfortunately, kids grow so fast that this longevity is lost on them and their bags quickly become obsolete. As a result, few parents are willing to shell out $300 for a bag that’ll only last a year. Mountain Hardware realized this doesn’t have to be the norm and released the Bozeman — an adjustable sleeping bag that expands as your child grows.

The key to the Bozeman is an internal drawstring that shrinks the bag to the height of the child. This internal closure ensures the child stays nice and warm in a space sized specifically for their height. As the child grows, the drawstring can be adjusted to a new length. Each year the bag gets a little bit longer until the child is ready for an adult-sized model.

When deciding what to put in the Bozeman, Mountain Hardwear didn’t scrimp. The company started off with enough synthetic fill to produce a bag that’s comfortable down to 20 degrees Fahrenheit, ensuring a full three seasons of usage. Mountain Hardwear also included a draft tube along the zipper and a face gasket to keep cold air out and the warm air in.

Big Agnes Sentinel 30

The best double sleeping bag

Why should you buy this: The Big Agnes Sentinel 30 takes all the features of a high-end sleeping bag and packages them into a form factor built for two.

Who’s it for: Couples who enjoy spending time together outside.

Temperature rating: 30 degrees Fahrenheit

Weight: 3 pounds, 9 ounces

Fill: 650 Fill DownTek water repellent down

Why we picked the Big Agnes Sentinel 30:

The Sentinel 30 from Big Agnes is all about sharing your love of the great outdoors with your favorite person. The down sleeping bag is designed to hold two people comfortably with room for sleeping pads in the integrated sleeve. Rated down to 30 degrees Fahrenheit, the full package brings a bed-like comfort to your camping experience.

The most striking feature of the Sentinel 30 is its size — the double bag measures almost 9-feet across the shoulders and hips, accommodating two people up to 6-feet tall. It weighs 3 pounds and 9 ounces, which is reasonable for such a large bag. Instead of unpacking two sleeping bags and struggling to zip them together, campers simply roll out the Sentinel 30 and hop right into bed. Its weight, however, makes the Sentinel 30 more suited for car camping instead of backpacking.

Although it’s meant for two people, the bag does have some individualized features. Each person has the option to use their pillow in the integrated pillow barn and cinch the hood based on their need for heat. The bag also allows owners to choose between two individual sleeping pads — or one double pad — if both sleepers can agree on the firmness and thickness of the mattress pad. Each side also has its own zipper, meaning a person can get in and out of the bag without waking up their partner.

The Sentinel 30 is big in size and big in features. Thanks to DWR on the outside and water-repellent down on the inside, the Sentinel 30 is designed to keep you dry and warm even when the conditions turn wet. There are also interior fabric loops to hold sleeping bag liners in place and a free range hood which allows you to lift your head without adjusting the hood.

Kelty Cosmic 20

The best sleeping bag for the budget-conscious

Why should you buy this: The Kelty Cosmic 20 keeps you warm in three season conditions at an extremely affordable price.

Who’s it for: Budget-conscious campers and backpackers

Temperature rating: 20 degrees Fahrenheit

Weight: 2 pounds, 13 ounces

Fill: 18 ounces of 600 fill DriDown

Why we picked the Kelty Cosmic 20:

To find something as warm and lightweight as the Kelty Cosmic is truly remarkable. The Cosmic is a high-quality mummy bag designed for durability and comfort. It has a durable 50D taffeta lining that feels soft to the skin and a snug hood with a draft collar to keep your body heat in and the cold weather out.

Kelty designed the Cosmic 20 with 600 fill DriDown, a water-resistant down which prevents moisture from compromising its excellent lofting capacity. In addition to the down filling, the Cosmic 20 features a rugged 50D down-proof outer fabric that prevents the loss of down and baffles which reduce the occurrence of cold spots. A three-quarter zipper makes it easy to use the sleeping bag as a quilt in warm conditions.

The Kelty Cosmic is rated to an EN lower limit of 19 degrees Fahrenheit and a comfort limit of 20 degrees Fahrenheit. If you’re looking for something warm enough for three season conditions, lightweight enough to take backpacking, and at a price point that won’t break the bank or sacrifice quality — the Kelty Cosmic should be on your radar. If 20-degrees doesn’t hit the sweet spot, then talk a look at the Cosmic 0 for four-season use or the Cosmic 40 for warmer climates. There’s also a women’s specific version.

Marmot Lithium 0-degree

The best sleeping bag for winter weather

Why should you buy this: An outstanding warmth-to-weight ratio for challenging the coldest winter weather.

Who’s it for: Winter campers and backpackers who want a warm sleeping bag.

Temperature rating: 0 degrees Fahrenheit

Weight: 2 pounds, 9.5 ounces

Fill: 800-fill goose down

Why we picked the Marmot Lithium:

When winter rears its head, the snow begins to fall, and the winds begin to howl, you don’t have to retreat indoors and out of the elements. You can camp or backpack all winter long with the Marmot Lithium and keep warm at night, even when the temperatures dip below freezing.

Marmot stuffed a healthy helping of 800-fill down into this performance mummy bag and added a Pertex DWR shell to repel moisture, making it ideal for use in snowy conditions. In addition to quality down, smoothly curved baffles prevent down drift and ensure maximum loft. The Lithium is rated to an EN comfort level of 0 degrees Fahrenheit and a lower limit of minus-4.5 degrees Fahrenheit.

Aside from an impressive warmth-to-weight ratio, the Lithium is extremely lightweight, making it ideal for use on a backpacking or alpine expedition. Tipping the scales at just 2 pounds, 9.5 ounces, it rivals many of the bags on this list — including those that are significantly less warm.

How we test

When possible, our sleeping bag recommendations have been field tested across a variety of terrains and weather conditions. We try to test each bag under the conditions which it will be most frequently used. When testing a sleeping bag is not possible, we look at the features of the bag and compare it to existing models in our arsenal of gear. We examine how the bag has changed and what improvements, if any, were made for the current year. We also comb through product specifications and both manufacturer and retailer videos for insight into any new technology advances that were developed for these latest and greatest sleeping bags.

Things to consider

Buying a sleeping bag is a very personal thing. Everyone sleeps differently — there are warm sleepers, cold sleepers, side sleepers, back sleepers and more. Because of this variability, there is no perfect sleeping bag suitable for everyone. As a result, you have to spend time researching a sleeping bag before purchasing. Buying a sleeping bag comes down to three things: the type of insulation (down or synthetic) in the bag, the size, and weight that you can carry, and the level of comfort you want in the field.

Down vs. synthetic insulation

One of the biggest decisions you need to make about when purchasing a sleeping bag is the insulation. The insulation influences how warm you will be when you backpack. There are two basic types of insulation — down and synthetic — and they have very different properties.

Down is known for being lightweight and warm. It can be compressed to a fraction of its original size and takes up relatively little space in your pack. Down has an Achilles heel, though. When wet, it loses its ability to keep you warm. Down has a loft that creates air spaces between the feathers. When this air heats up, it’s able to keep you warm inside your sleeping bag. When down gets wet, it sticks together and loft disappears. As a result, the bag stays cold because it no longer has these air spaces to trap heat.

Synthetic insulation, on the other hand, does not rely on loft to keep you warm. The insulation itself is developed with specialty materials and woven fabric matrices that are designed to trap heat. When this insulation gets wet, it retains its ability to keep you warm. This capability is a huge benefit for backpacking in a wet area.

Like down, synthetic insulation does have a downside. The material is heavier than down and not nearly as compressible. As a result, synthetic bags are heavier and take up more room than their down counterparts.

Seasons and temperature ratings

Another major factor in choosing a sleeping bag is the temperature rating. You don’t want to pack a 50-degree bag in the dead of winter, nor do you want to pack a 0-degree bag in the middle of summer.

Each bag has a temperature rating which helps you choose the best model for your outings. Many sleeping bags list an EN rating, which is a testing standard used by most major sleeping bag manufacturers. This specification ensures the bags are evaluated using the same set of criteria, allowing you to compare an 800-fill down bag from Mountain Hardware with a 650-fill down bag from the North Face. There are usually two EN values listed for each bag — the EN comfort rating and the EN lower limit rating.

The comfort rating is the lowest temperature that the average woman will find comfortable, while the lower limit reflects the lowest temperature that is comfortable to the average man. These temperatures are calculated based on a person wearing a single layer of long underwear and a hat. Some bags don’t have an EN rating, so you’ll need to look at the insulation type and its relative reviews to see whether the bag lives up to its advertised temperature rating.

Do keep in mind ratings are only a guideline and should be applied to your unique physiology. Everyone is different — for instance, some people sleep warmer and are comfortable in a 30-degree bag when it is well below freezing while others sleep much colder and need a 30-degree model even during warm summer nights. Typically, three-season bags, with a range from five degrees Fahrenheit to 29 degrees Fahrenheit, are the most popular bags as they can be used from spring through the fall.

If you do almost all of your backpacking and camping in the summer, you’ll want a warm weather bag with a temperature range that extends from 30 degrees Fahrenheit on the low end to 55 degrees Fahrenheit on the upper end. For winter, you want to select a bag with a range that extends from four degrees Fahrenheit to negative-40 degrees Fahrenheit. Don’t worry if your bag is a little too warm or cold for the conditions. If cold, you can add a liner or an extra layer of clothing to boost 10 degrees Fahrenheit in warmth. Likewise, you can simply open a zipper to create a vent, or even unzip a bag fully and use it as a blanket to cool off.