How to choose the best sleeping bag for you

By Sea to Summit

No sleeping bag is right for everyone but finding the best sleeping bag for you is a game-changer.

After all, a good sleeping bag is going to give you the rest and recovery you need to keep exploring. It's what's going to see you through overnight adventures for years to come.

There's a lot more to consider than reviews or budget when choosing this vital bit of your sleep system. You need to think about how you’re going to use it and how you’re going to get it there. And you definitely need to consider what the weather may throw at it.

Here's everything you should consider when choosing a sleeping bag.

Sleeping Bags: Choose your adventure

The best sleeping bag for you depends on what kind of outdoor activities you're into.

Thru-hiking the Appalachian Trail? Your sleeping bag needs to be as light and compact as possible, like our Spark and Flame range. Taking a paddle trip? A technical synthetic bag like our Trailhead and Quest might be your best insurance policy against wet conditions.

To match people with the right sleep system, we ask them to choose their top three activities. There's a sleep system to suit everything from hiking and backpacking to mountaineering, bikepacking and overlanding.

Activities—the first thing we ask you about on our Sleep Systems Finder

How warm does your sleeping bag need to be?

If a sleeping bag had just one job to do, it would be to keep you alive. It needs to protect you from hypothermia and other cold-related injuries.

Make sure your sleeping bag is also warm enough to stop you shivering all night. Poor quality sleep makes for some pretty gruelling outdoor experiences. And on more technical expeditions, fatigue is downright dangerous.

EN Ratings

EN temperature ratings are your best bet at choosing a sleeping bag in the right temperature range. It’s the most standardised independent test in the industry and is backed by the most respectable outdoor designers.

The EN rating scale help you choose a sleeping bag that will keep you warm enough at the lowest temperature you intend to sleep in. Most men should refer to the Lower Limit rating for this. Women, who usually sleep a few degrees colder than men, should refer to the Comfort rating.

Women's specific sleeping bags

If you're a cold sleeper, a women’s specific sleeping bag—like our AltitudeJourney, Venture and Quest—might be the solution. These bags have extra insulation where you need it most and come in Regular and Long. Remember that the Women’s Regular is for sleepers up to 167cm / 5’6” and the Women’s Large is for sleepers up to 183cm / 6’0”. Taller bags can be found in our unisex range.

Sleeping bags for colder conditions

Sleeping bag draft tubes along the zippers and a full draft collar are essential for retaining warmth in colder conditions. They prevent heat ‘leaking out’ along the zippers or around your shoulders. The oversized draft tubes/draft collars on our Ascent or Altitude bags excel at this.

Remember that the manikin used in the EN temperature rating test does not move. It doesn't draw cold air into a sleeping bag. In the real world, where people move around in their sleep, these construction details are vital.

PRO TIP: Consider adding heat to your bag with a Reactor/Reactor Extreme Thermal Liner or Spark 0.

Sleeping bag weight

There’s a reason some people obsess over grams. When you’re lugging all your kit up a mountain for days at a time, all that weight adds up. It really does.

Down sleeping bags

The sleeping bags with the best warmth-to-weight ratio are down sleeping bags. A synthetic bag can be just as warm but it will normally be heavier and bulkier.

The higher the Loft number, the more packable and light your bag will be for the same warmth. A 650+ Loft down bag is great for car camping. But a 750+ and 850+ Loft is our top pick for fast-and-light expeditions.

Each of the above chambers is filled with 1oz (28g) of fully-lofted down

If you’re choosing a down bag, choose one that uses ethically-sourced hydrophobic down. At Sea to Summit, we use RDS certified ULTRA-DRY™ Down. And all our customers receive a certificate of authentication with every bag. Responsible Down Standard (RDS) certification requires third party assessments to ensure the welfare of animals throughout the entire supply chain. 

Synthetic sleeping bags

Synthetic bags are typically heavier and bulkier than down bags. However, synthetic has come a long way in the last few years. Insulated brands like THERMOLITE® have gotten particularly good at mimicking the best qualities of down.

Cross section of Sea to Summit's unique Waveloft™ construction

Construction also goes a long way in getting the most out of synthetic fill. At Sea to Summit, our synthetic bags use a WaveLoft™ construction. WaveLoft™ construction is where we loop the insulation and sew it into the lining. This helps the insulation gain extra loft and trap pockets of air. It also eliminates the frustration of getting tangled in loose lining.


L-R: Explore Double, Ascent II, Flame I, Spark I and a 22cm-high water bottle

For activities like bikepacking, bike touring and motorcycle touring, there's more wriggle room on weight—and less on packed size.

For trips like these, a down sleeping bag with lightweight materials is your most compact companion. And a compression sack can further reduce packed size by 30–40%.

Many of our bags come with a compression bag but these can also be purchased separately. Compression dry sacks—like our eVent® Compression Dry Sack and Ultra-sil® eVent® Compression Dry Sack—will also protect your bag from the elements.

Sleeping bag Fit

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The right fit needs to do two things—keep you comfortable and not compress the insulation in the bag.

Both down sleeping bags and synthetic sleeping bags need to loft up to effectively insulate. If your bag is too tight, it will compress the insulation and create cold spots. So choose your fit wisely.

Our unisex bags come in a range of relaxed-tapered to rectangular shapes. Our women’s specific range is narrower in the shoulder and wider from the hip-to-knee. Measure yourself and check the dimensions of bags from both these ranges to figure out which one is right for you.

Or why not just forget about fit altogether and get yourself an Ember Quilt? It's a seriously technical and versatile choice.

PRO TIP: Don't underestimate the importance of comfort. If your bag is too tight, you’re going to feel too restricted to get comfy. This is why even our most tapered bags are roomier than many out there. At a certain point, a snugger fit is going to be counterproductive.


Once you have your bases covered—warmth, weight, packability and fit—it’s time to consider features that make your life easier and more comfortable on the trails. Here are a few of our favourites:


Our Free-Flow triple zip system can be found in our Altitude, Ascent, Traverse and Venture.

The most versatile bags—the ones that will see you through different temperatures and terrain—are normally those that have ventilation options. Just open up your sleeping bag to let out excess heat. Some models can even be opened completely flat like a quilt, for true three-season flexibility.

Bags with our Free-Flow triple-zip system—like our Alpine, Ascent, AltitudeVenture and Traverse—offer the most ventilation options. Zips on each side of the bag allow you to fold the top down. And a third zipper in the footbox frees your feet.

Many of our other bags use secondary zips or zip sliders to allow ventilation. This gets you more use out of your bag for negligible extra weight.


Pockets might not sound like the most exciting feature out there—but they come in pretty handy when you want to keep your batteries or technology safe from freezing temperatures.

Zip Coupling

L-R: Ascent + Altitude, Trek + Journey

Bags with our Zip Coupling feature can be paired with one another.


Just to make matters more complicated—you should really be asking yourself how your sleeping bag fits into your sleep system. We're talking your sleeping bag, mat, liner and pillow.

When it comes to your sleep set-up, one bit of gear affects the other. The mat you choose will determine how warm your sleeping bag needs to be. Your sleeping liner will boost temperature too (and keep your bag clean for the long haul). As for your pillow, well—have you tried sleeping on a stuff sack full of dirty clothes? For the difference of 60g, you could make or break a night of rest and recovery.


Just like finding the right sleeping bag, there’s a lot to consider when it comes to setting up your perfect sleep system.

Luckily, our Sleep System Finder does all the work for you. We know what to ask to find you your best night's sleep outdoors.