The best 4-season sleeping bags 2023: cozy bags for year round camping

Collage of eight of the best four-season sleeping bags on white background
(Image credit: Future)

When it comes to the best 4-season sleeping bags, one thing is for sure: unless you find yourself camping high on an 8000-meter peak or in Antartica, you should be fairly warm. So, for 99.99% of people, the sleeping bags in this selection are great options for camping adventures all year round.

Of course, there's a caveat here. We wouldn't recommend getting into a winter-rated sleeping bag during a July heatwave, but hopefully this is common sense. However, with spring upon us, you'll still get plenty of use out of these toasty bags.

If you're a mountain-loving wild camper, the temperatures up high during both spring and fall will probably demand more than your average 3-season sleeping bag. In this case, you'll really benefit from one of the best 4-season sleeping bags, regardless of whether they're filled with down or synthetic materials.

In this guide, we start with some serious warm winter-ready bags, before moving on to versatile 4-season options, some great bags for bivying and finish with some excellent car camping bags. The difference between 4-season and winter outdoor gear can be a little unclear. To help you know what to look for when buying a 4-season sleeping bag, see our 'how to choose' guide at the bottom of this feature.

Best winter sleeping bags

Rab Andes 800 Down Sleeping Bag in tent

(Image credit: Matthew Jones)
A seriously warm bag for seriously cold conditions, the Andes 800 is a 4-season warrior that is even at home at high altitudes in the world’s great ranges

Specifications

Weight: 1,360g / 48oz
Pack size: 45cm x 28cm / 17.7in x 1in
Shell: 13D Gore-Tex Infinium fabric (45gsm) with DWR
Lining: 20D nylon ripstop with TILT reflective technology (35gsm)
Fill: 800FP European goose down with Nikwax PFC-free hydrophobic finish (800g / 28.2oz)
Comfort rating: -23°C / -10°F

Reasons to buy

+
Extremely warm
+
Moisture-resistant down and fabrics
+
Great hood

Reasons to avoid

-
Expensive
-
Tapered cut isn’t the roomiest
-
No compression stuff sack

A top-quality 4-season sleeping bag, the Andes Infinium 800 is well equipped to deal with temperatures that drop way below freezing. But thanks to premium 800FP down insulation, it’s also competitive in terms of both weight and packability for a bag of this class. 

There’s more, though. Unlike most down rivals, the Andes Infinium 800 is a far more practical choice for use in damp conditions. The fill is treated with a hydrophobic finish, while the shell fabric is made from Gore-Tex Infinium. As such, it’s highly moisture resistant, making it a viable prospect even for cold weather use in predominantly wet climates.

Rab have also added a shiny TILT lining to the interior of the bag, which adds next to no weight but is designed to reflect radiated heat back to the body, further boosting its overall warmth. So too do other design features like the carefully considered baffle arrangement, tapered mummy cut, snug hood and contoured foot box.

Read our full Rab Andes Infinium 800 sleeping bag review

Mountain Hardwear Bishop Pass 15F/-9C

(Image credit: Berne Broudy)

2. Mountain Hardwear Bishop Pass 15F/-9C

Excellently priced, very warm bag

Specifications

Weight: Reg: 1 kg / 2lb 5.4oz; Long: 1.1kg / 2lb 7.9oz
Length: Reg: 218cm / 86in; Long: 234cm / 92in
Pack size: 20cm x 39.5cm / 8in x 15.5in
Body fabric: 20D Ripstop Nylon 39g/m²
Fill: 650 fill down RDS cert / fluorine free
Comfort rating: -9°C / 15°F

Reasons to buy

+
Available in women’s and men’s
+
RDS down
+
Available in left and right zips

Reasons to avoid

-
Too snug for some sleepers
-
No compression stuff sack

With all the bells and whistles of much more expensive bags, Mountain Hardwear’s Bishop Pass Sleeping Bag uses high-quality, ethically-sourced, 650 fill power down certified to the Responsible Down Standard (RDS). The down is blown inside a wear- and tear-resistant 100% nylon shell for a sleeping bag that’s light and compressible, and easy to pack and carry. That makes it an ideal sleeping bag for backpacking. One of the other great features of the Bishop Pass is that it’s treated with a water-repelling finish that prevents it from getting wet from condensation inside the tent. 

The Bishop Pass has many of the features of the most technical winter camping bags, including a contoured draft collar and insulated face gasket that together trap your body heat inside the bag instead of letting heat out and cold in. A full-length draft tube further insulates the bag by preventing cold air from entering through the Bishop Pass’ two-way zipper. The bag is close-fitting; that means that once you’re inside, you’ll feel warm fast because there isn’t a lot of extra space for your body to warm up. While the bag is trim, the square foot box is spacious; this means that your feet won’t feel cramped or claustrophobic, which will keep them warmer and help you sleep better. 

Best 4-season sleeping bags

Nemo Kayu Women’s Down Mummy Sleeping Bag on forest floor

(Image credit: Berne Broudy)

3. Nemo Kayu Down Mummy Sleeping Bag

A warm mummy-shaped sleeping bag

Specifications

Weight: 1.1kg / 2lb 8oz
Suits campers up to (height): 5ft 6in / 168 cm
Pack size: 32cm x 20cm / 12.5in x 8in
Fill: RDS 800 fill down
Comfort rating: -7.8°C / 18°F

Reasons to buy

+
Available in men’s and women’s versions
+
DWR Coating
+
Outer stow pocket
+
Articulated hood

Reasons to avoid

-
Women’s version is a bit short (women over 5ft 7in should opt for the men’s version)

Made from extremely light and compressible Responsible Down Standard-certified insulation that’s been treated to repel water, this bag has several distinguishing features. 

Its sculpted mummy shape is contoured to follow the body’s curves for thermal efficiency, warmth retention and packability. Zippered gills on the front of the bag let you fine-tune the bag’s warmth without fully unzipping and exposing your body parts to the cold. The gills are sewn into the nylon ripstop shell on the front. Unzip the gills and they let heat out when you’re too warm without letting cold air in. 

The bag has a three-quarter zip for ease of entry and exit. Its silky-feeling shell is enhanced with waterproof panels on the hood and foot box to keep the bag from getting wet from condensation where your head or foot might touch a tent wall. The insulation – which is blown into vertical baffles – is extremely warm for the weight. And the Kayu comes with a lifetime warranty. 

OEX Leviathan EV 900 sleeping bag on grass outdoors

(Image credit: Craig Taylor)
A down-filled 4-season sleeping bag that promises big things for a comparably low price tag

Specifications

Weight: 1,370g / 3lb
Pack size: 19.3in x 23.6in / 49cm x 60cm
Length: 220cm / 87in
Fill: 900gsm / 600 fill power duck down
Comfort rating: -9°C / 15°F

Reasons to buy

+
Reasonably priced
+
Packs down small
+
Quite light
+
Very cosy

Reasons to avoid

-
Only comes in one (nasty) color
-
Temperature ratings are slightly generous

The Leviathan EV 900 is a solid 4-season sleeping bag with an impressively low comfort rating for the price. Designed by OEX, which is UK outdoor retailer GO Outdoors’ higher-end own brand, the bag comes with great specs for a low price, and it can often be picked up even more cheaply during one of the numerous sales put on by the Sports Direct-owned retailer throughout the year.

The OEX Leviathan EV 900 has a comfort rating of -9°C (15°F). It comes stuffed with 900 grams (30 ounces) of hydrophobic 600 fill power ethically sourced duck down, and the shell is made from 20D nylon. Featuring a thick baffle along the length of the side zip, as well as a huge baffle and lofty hood around the top of the bag, it’s built to keep you warm in colder climates – and in our tester’s experience, it does just that. 

Weighing 1,370g (3lb), the Leviathan 900 is also reasonably lightweight, considering the temperatures it is designed for. And while there are bags out there that will deliver an equivalent level of warmth at a fraction of the weight, there’s simply no beating it at this price point. 

We do think the temperature ratings are a little generous, and that to get any sleep at -9°C (15°F) you would need some serious base layers on.

Our only gripe with the bag is, in fact, the thing that matters least when you’re deep in the backcountry: the color… a sort of yucky greeny yellow.

Read our full OEX Leviathan EV 900 sleeping bag review

4-season sleeping bag: Patagonia Fitz Roy Down Sleeping Bag

(Image credit: Kim Fuller)

5. Patagonia Fitz Roy Down Sleeping Bag

High-end, eco-conscious and warm sleeping bag for backpacking in all seasons

Specifications

Style: Baffled, down sleeping bag
Shape: Mummy
Temperature rating: -7°C / 20°F
Weight (regular): 1,021g / 36oz
Length: Suitable for users up to 183cm / 6ft (Short is suitable for users up to 168cm / 5ft 6in; Long: 198cm / 6ft 6in)
Filling: 800-fill-power certified traceable down
Materials: Shell and Liner: 100% recycled nylon ripstop with PFC-free DWR finish
Compatibility: 4-season camping
Zip options: Central
Colors: Blue

Reasons to buy

+
800-fill-power down is very warm and lofty
+
Three lengths available
+
Hood design is like a jacket for ideal fit
+
Sculpted footbox keeps feet extra warm
+
Internal chest pocket keeps essentials warm and accessible
+
Water-resistant shell
+
Eco-conscious with Advanced Global Traceable Down, 100% recycled and solution-dyed fabrics, and Fair Trade Certified sewn

Reasons to avoid

-
Central zip won’t suit everyone
-
One of the pricier sleeping bags on the market
-
This bag is heavier than ultralight backpacking options
-
Pack sack could offer more compression support

This down sleeping bag from Patagonia is named after the region's most famous mountain: Mount Fitz Roy (properly known as Cerro Chaltén), an astonishing peak on the border between Argentina and Chile. It's a high-end option designed for use in cold weather conditions. The Patagonia Fitz Roy Down Sleeping Bag comes in two temperature rating options: the 20°F / -7°C version, which we tested, and a 30°F / -1°C version. There are also three length options to choose from: short, regular, and long. The bag is filled with 800-fill-power Advanced Global Traceable Down, which is ethically sourced and provides excellent insulation. 

One of the key features of this sleeping bag is its vertical baffles – this design helps to keep the down evenly distributed throughout the bag and prevents cold spots from forming. The bag also has a full-length zipper and a lid that works like a jacket hood for optimal fit and warmth retention.

The Patagonia Fitz Roy Down Sleeping Bag is packable and works well for trekking in the backcountry, but it is not the lightest and most compressible option. The stuff sack does help to reduce the overall size of the bag, but a more helpful compression sack with side straps would be nice. Overall, the Patagonia Fitz Roy Down Sleeping Bag is a high-quality option for camping in cold weather conditions. While it is more expensive than some other sleeping bags on the market, its advanced materials and features make it a worthwhile investment to ensure you’ll be camping comfortably.

best 4-season sleeping bag: Snugpak Softie Expansion 5

(Image credit: Alex Foxfield)
A luxurious feeling synthetic sleeping bag that punches way above its weight considering the price point

Specifications

Weight: 2.3kg / 81oz
Length: 220cm / 87”
Pack size: 32cm x 26cm / 13" x 10"
Fill: Polyester Softie insulation
Comfort: -15°C / 5°F
Limit: -20°C / -4°F

Reasons to buy

+
Plush, luxurious and warm
+
Great for winter camping
+
Can regulate temperature with expander panel
+
Retains thermal qualities when wet
+
Great value

Reasons to avoid

-
Very heavy
-
Larger pack size than most

Snugpak’s polyester Softie insulation has been a mainstay in the British brand’s products for over thirty years. It utilizes superfine yarns bound together with special resins to mimic the properties of natural insulation such as down. The result is a really plush feeling bag that is easily warm enough for winter camping trips.

This bag is a gloriously cozy cocoon to nestle within and, with a comfort limit of -15°C (5°F), it is wonderfully toasty in all but the most Baltic conditions. However, it's limited to sub-zero use, as its elasticated expander panel allows the user to open things up, thus regulating the temperature inside.

As its fill is synthetic, it's not as light or packable as many of its down-filled counterparts, so isn't ideal for long backpacking missions. However, it’s a mere fraction of the cost of some of the leading down bags. Great value then, especially considering its luxurious feel and the amount of warmth it retains.

Read our full Snugpak Softie Expansion 5 review

4-season sleeping bags: Mountain Warehouse Microlite 1400 Winter Sleeping Bag

(Image credit: Pat Kinsella)

7. Mountain Warehouse Microlite 1400 Winter Sleeping Bag

A seriously warm synthetic sleeping bag available for a bargain price

Specifications

Style: Synthetic fill backpacking bag
Shape: Mummy
Temperature rating: Comfort: -4°C/25°F ; minimum: -11°C/12°F
Weight (regular): 1,900g / 67oz
Length: Regular: 200cm/79in (max user height 180cm / 5’9”); Long: 215cm/84.5 (max user height 195cm / 6’4”)
Pack size (regular): 20cm X 44cm / 8 x 17in
Filling: Synthetic microfibre (100% polyester)
Compatibility: cold weather camping, backpacking or car camping
Zip options: Left or right
Colors: Blue or burnt orange

Reasons to buy

+
Warm enough for 4-season camping
+
Retains thermal properties when damp
+
Left/right zip options
+
Well featured 
+
Excellent price
+
East to look after

Reasons to avoid

-
No recycled content
-
Not as lightweight or compressible as down 
-
Not as comfortable as down

Four-season sleeping bags don’t have to cost a fortune, as this excellent offering from Mountain Warehouse proves. The microlight 1400 might not be as featherlight, packable or quite as sumptuous feeling as down-filled sleeping bag, but it is certainly light enough to be taken on backpacking adventures, and is more that capable of keeping you warm in most conditions likely to be encountered during the vast majority of the year in non-alpine terrain. It’s perfectly suited to those early spring camping escapades, when days are getting warmer but nights can still be super shivery if you don’t have the right gear. And it is very reasonably priced.

Available in versions to suit left or right handed people, the two-way zip can be opened from the bottom or top (to give you ventilation options) and is backed by a storm flap to keep breezes out. It boasts a good, shaped hood, which can be pulled tight around your face, and has inner pockets for keeping valuables safe, or phones warm and handy. It comes in two lengths, regular and long, and the ripstop outer fabric is robust and should last for many chilly seasons.

REI Co-op Down Time 25 Down Sleeping Bag on forest floor

(Image credit: Berne Broudy)

8. REI Co-op Down Time 25 Down Sleeping Bag

A versatile and comfortable bag, but not for really low temperatures

Specifications

Weight: 3lb 3oz - 3lb 6oz / 1.45kg-1.5kg
Pack size: 8in x 14in / 20.3cm x 25.6cm
Suits campers up to (height): Regular: 66in / 167.5cm; Long: 72in / 183cm
Fill: Water-repellent 600 fill power duck down
Comfort rating: -4.4°C / 24°F

Reasons to buy

+
RDS Down
+
Good eco story
+
Full zip
+
Available in men’s and women’s versions

Reasons to avoid

-
Bulkier than some other bags
-
Compression stuff sack not included

Made for adventurers who won’t likely camp when it’s much below freezing, REI’s Down Time 25 has the bells and whistles to make sleeping out great, as well as a robust and verified eco story. 

The mummy-shaped bag uses a no-snag zip with a draft tube that’s been sewn flat to make it even more unlikely the zipper will snag. The Down Time 25 uses 600 fill duck down insulation that’s slightly less compressible than higher-fill power goose down. But it’s bluesign approved and meets the Responsible Down Standard. It’s also treated with a water-repelling finish to help it fend off moisture and dry faster. 

The Down Time gives campers room to move with its relaxed mummy shape. The women’s bag has wider hips and narrower shoulders. Both men’s and women’s bags will be comfortable for people who tend to flip from stomach- or back-sleeping to side-sleeping during the night. The bag’s baffles are sewn with variated-width stitching that keeps the down evenly distributed within the bag, preventing cold spots. 

Kelty Cosmic Down 20 sleeping bag on forest floor

(Image credit: Berne Broudy)

9. Kelty Cosmic Down 20

A very affordable 4-season sleeping bag that’s well designed and intelligently featured

Specifications

Weight: 3lb 7oz / 1.56 kg
Length: 59in / 150cm
Pack size: 20cm x 33cm / 8in x 13in
Suits campers up to (height): 5ft 8in / 172cm
Fill: 550 fill down
Comfort rating: 0°C / 32°F

Reasons to buy

+
Great value
+
Draft tube and draft collar
+
Soft-on-the-skin shell fabric
+
Full zip (left and right available)
+
Available in men’s too

Reasons to avoid

-
Down isn’t certified for the ethical treatment of animals, or fair trade practices
-
Stuff sack is non-compression

The award-winning Kelty Cosmic Down is one of the most affordable down backpacking sleeping bags you can buy. Where other bags use horizontal or vertical baffles to hold insulation, this one uses trapezoids for thermal efficiency and to keep the bag from having cold spots. 

The outer shell of the bag is coated with a PFC-free water-repellent that beads water and repels moisture. Inside, 550 fill down insulates and traps warm inside. A zippered internal stash pocket holds a headlamp, ID, earplugs and more. The bag opens and closes with a two-way, anti-snag zipper that allows for ventilation from the feet and from the shoulders when needed. 

This bag is tried and true. In its latest iteration, Kelty increased the size of the foot box to make it non-constrictive for most feet. The bag comes with both a storage sack and a stuff sack in short, regular and long lengths and in both men’s and women’s silhouettes. While both bags are relatively affordable, the women’s costs more owing to the fact that it has more insulation because, in general, women sleep colder.

Best 4-season sleeping bags for bivying

Exped Waterbloc Pro -15° sleeping bag on grass

(Image credit: Emily Woodhouse)
The lightest weatherproof down sleeping bag on the market

Specifications

Weight: Small: 2lb 11oz / 1,225g; Medium: 2lb 13oz / 1,280g; Large: 2lb 15oz / 1,340g
Length: Small: 75in / 190cm; Medium: 81in / 205cm; Large: 87in / 220cm
Pack size: Small: 10.6in x 6.7in x 5.9in / 27cm x 17cm x 15cm; Medium: 10.6in x 6.7in x 6.3in / 27cm x 17cm x 16cm; Large: 10.6in x 6.7in x 6.7in / 27cm x 17cm x 17cm
Fill: 800+ cubic inches/oz goosedown
Comfort rating: -6°C / 21°F

Reasons to buy

+
Waterproof
+
Storm flap on zip
+
3D foot box

Reasons to avoid

-
Question marks over temperature rating

The Exped Waterbloc Pro sleeping bag is a 4-season sleeping bag designed with bivying in mind. It has 800 fill down, making it very soft and warm, with a Pertex outer shell that repels the weather. 

Although it is sold as waterproof in some marketing material there is also a disclaimer that you obviously can’t lie out in a downpour and expect to stay dry. Not that you want a completely waterproof sleeping bag anyway – that’s what bivy bags are for and a zero breathability sleeping bag sounds like a sticky night’s sleep. That said, Exped have gone out of their way to make this sleeping bag as water resistant as possible: the entire outer shell has barely any seams, the zip has a Pertex storm flap and the 20D Pertex Quantum Pro has a 1000mm water column. 

In terms of comfort, this is a very lofty sleeping bag with lots of attention paid to keeping unwanted cold air out. There are draw cords around the hood and neckline, plus an extra down collar around the neck. Behind the zip has a similar draft excluder and the foot box has been specially engineered to stop cold spots. 

The one question is on the actual temperature ratings. It’s called a -15° sleeping bag but the comfort, limit and extreme temperatures listed on the website are different (warmer) to those printed inside the bag. And surprisingly none of those numbers are -15°.

Read our full review of the Exped Waterbloc Pro -15°

Best 4-season sleeping bags for car camping

4-season sleeping bags: Highlander Serenity 450 Mummy Sleeping Bag

(Image credit: Alex Foxfield)
A wonderfully warm cocoon for winter camping adventures, the Serenity 450 is a quality sleeping bag at an unbeatable price

Specifications

Weight: 2kg / 70.5oz
Length: 220cm / 86.6in
Pack size: 41 x 26 x 26cm / 16 x 10 x 10in
Fill: 450gsm SFX spiral polyester hollowfibre
Comfort limit: --4°C / 24.8°F
Limit: -10°C / 14°F

Reasons to buy

+
Suitable for winter camping
+
Retains thermal qualities when wet
+
Cozy, snug and warm
+
Internal security pocket
+
Great value

Reasons to avoid

-
Large packed size
-
Heavy

A great value synthetic bag that's well equipped for winter camping. Wonderfully insulated and capable even when wet, it will keep you warm even when it’s just beyond freezing outside. Its size and weight make it less appealing than a premium down bag for sustained backpacking, but for single night wild camping or year-round car camping, it’s a solid option.

Despite its weight, the Serenity does have the advantage of being only a fraction of the price of a premium down bag, so it’s perhaps more prudent to put it in the ring with other synthetic winter bags. In such a bout, the Serenity holds its own in terms of weight and pack size.

The full length two-way zip is accompanied by an insulated side baffle to keep the warmth in. There are draw cords on both the hood and the shoulder baffle, so things can be tightened up if things get truly Baltic. Also on the inside by your chest is an internal security pocket, which is fastened by a Velcro tab. This is useful for items like a phone or headlamp.

Read our full Highlander Serenity 450 Mummy Sleeping Bag review

Best 4-season sleeping bags and winter sleeping bags – Slumberjack Ronin 20

(Image credit: Berne Broudy)

12. Slumberjack Ronin 20

A very roomy cocoon, perfect for winter car camping

Specifications

RRP: $89.95 (US)
Weight: 2.6kg / 5lbs 11oz
Length: 213cm / 84in
Pack size: 32cm x 51cm / 12.5in x 20in
Fill: Slumberloft synthetic insulation
Comfort rating: -7°C / 20°F

Reasons to buy

+
Dual zips and velcro tabs lets you stay tucked inside with your arms outside the bag
+
Lots of venting options
+
Budget pricing

Reasons to avoid

-
Comes in one size that’s quite a large side
-
Heavier than most bags
-
Bulky

One of the most spacious mummy bags you can buy, Slumberjack’s Ronin is cut tall and wide with an oversized foot box that won’t cramp your style even if you have extremely large feet. Best suited for base camping and car camping, the Ronin has two three-quarter-length zippers, and each zipper has velcro tabs designed to let you partially unzip it while remaining inside the bag so that you can cook, play cards, read, write in your journal and more without getting cold. 

When it’s warm, the dual zippers let you fold back the top of the sleeping bag like a quilt, providing a lot of venting. The hood turns inside out and becomes a pillow when stuffed with clothing. 

The Ronin -20 is insulated with synthetic fill, which doesn’t compress quite as well as down, but it's warm when wet. And the Ronin is extremely durable, while the price tag makes it accessible. 

Swipe to scroll horizontally
Best 4-season sleeping bags and winter sleeping bags comparison table
Sleeping bagList priceWeightPack sizeComfort rating
Rab Andes 800 Down Sleeping Bag$700 (US) / £800 (UK)1,360g / 48oz45cm x 28cm / 17.7in x 1in-23°C / -10°F
Mountain Hardwear Bishop Pass 15F/-9C$275 (US)Reg: 1 kg / 2lb 5.4oz; Long: 1.1kg / 2lb 7.9oz20cm x 39.5cm / 8in x 15.5in-9°C / 15°F
Nemo Kayu Down Mummy Sleeping Bag$400 (US) / £370 (UK)1.1kg / 2lb 8oz32cm x 20cm / 12.5in x 8in-7.8°C / 18°F
OEX Leviathan EV 900£2701,370g / 3lb19.3in x 23.6in / 49cm x 60cm-9°C / 15°F
Patagonia Fitz Roy Down Sleeping Bag$559 (US) / £500 (UK) / €560 (EU)1,021g / 36oz-7°C / 20°F
Snugpak Softie Expansion 5£150 (UK)2.3kg / 81oz32cm x 26cm / 13" x 10"-15°C / 5°F
Mountain Warehouse Microlite 1400 Winter Sleeping Bag£80 (UK)1,900g / 67oz20cm X 44cm / 8 x 17in-4°C/25°F
REI Co-op Down Time 25 Down Sleeping Bag$229 (US)3lb 3oz - 3lb 6oz / 1.45kg-1.5kg8in x 14in / 20.3cm x 25.6cm-4.4°C / 24°F
Kelty Cosmic Down 20$214.95 (US) / £165 (UK)3lb 7oz / 1.56 kg20cm x 33cm / 8in x 13in0°C / 32°F
Exped Waterbloc Pro -15°£389 (UK)Small: 2lb 11oz / 1,225g; Medium: 2lb 13oz / 1,280g; Large: 2lb 15oz / 1,340gSmall: 10.6in x 6.7in / 27cm x 17cm; Medium: 10.6in x 6.7in / 27cm x 17cm; Large: 10.6in x 6.7in / 27cm x 17cm-6°C / 21°F
Highlander Serenity 450 Mummy Sleeping Bag£80 (UK)2kg / 70.5oz41 x 26 x 26cm / 16 x 10 x 10in-4°C / 24.8°F
Slumberjack Ronin -20$89.95 (US)1.6kg / 3lb 9.5oz32cm x 51cm / 12.5in x 20in-7°C / 20°F

How we tested the best winter sleeping bags

Our gear experts field tested each of the winter-rated sleeping bags featured in this guide while camping out overnight in a range of different locations, from North Wales to North America. Each was assessed against a set of criteria including comfort, warmth, features, packability and price.

For more details, see how Advnture tests products.

Choosing the best winter sleeping bag

Best winter sleeping bags - man high on mountain ridge

(Image credit: AscentXmedia / Getty Images)

When shopping for the best 4-season sleeping bag for your winter adventures, there are various things that you need to be aware of to ensure you’re making the right choice. Understanding these and then shopping for bags that deliver on the features you need most in accordance with your own budget is the best way to maximize bang for your buck. Otherwise, you’ll quickly see that the amount you can spend on winter bags is impressive to say the least…

So, before you go spending way too much for something that you’ll only be able to use a few times a year, here are some extra things for you to consider to help you camp in comfort and get a good night’s sleep.

Warmth and temperature ratings

You can trust Advnture Our expert reviewers spend days testing and comparing gear so you know how it will perform out in the real world. Find out more about how we test and compare products.

When it comes to temperature ratings, this is perhaps the single most important identifier of a true 4-season or winter sleeping bag. To be extra safe, you’re going to want to go big! In general, a “true” 4-season sleeping bag should be able to keep you warm in temperatures -7°C (20°F) or colder.

Don’t instantly believe everything published by manufacturers, however, as temperature ratings are notoriously flexible. Our bodies respond to cold differently, so where one person might sleep soundly in a sleeping bag at -7°C (20°F), somebody else using the same bag might shiver so much they crack a tooth. Conversely, a bag that keeps a cold sleeper comfortable in the winter might make warm sleepers too hot. So take the ratings with a pinch of salt and consider how warm or cold you tend to run. 

For the best gauge of a bag, pay close attention to the comfort rating: this is the temperature at which the average person should be able to comfortably sleep without waking for eight hours. The other ratings, namely the lower limit and the “extreme” limit relate to temperatures at which the bag should keep you alive, not happy. For safety reasons, you should steer well away from these, and if you plan on camping at -20°C (-4°F) , it’s important you get a bag with a comfort rating down to that temperature.

When using a winter bag for the first time, it’s always a good idea to give it a test run first before you commit to using it deep in the backcountry. Using it for a night in the garden or at a pitch close to the car is always a good idea; just so you know what the bag can cope with. 

REI Co-op Down Time 25 Down Sleeping Bag

The REI Co-op Down Time 25 Down Sleeping Bag in its packed down state (Image credit: REI)

Weight and packsize

Because of their additional insulation, 4-season/winter sleeping bags tend to be substantially bigger and heavier than their 3-season counterparts, so don’t be shocked by the numbers if you’ve not shopped for one before. The most heavy duty bags with comfort temperates of below -10°C (14°F) can weigh well over 3kgs, in fact, and will barely fit into a 60L rucksack. On the other hand, down-filled higher-end models with an equivalent temperature rating may get as light as 850g and pack down to the size of a soccer ball. Just be prepared to pay in excess of $1,000 for something like this.

Finding the balance is ultimately a question of your budget: getting a bag that’s super warm, ultralight and packs down small is going to cost you quite a lot of money – there’s simply no way around this. Instead, consider what type of adventures you’ll be using it on, be that long-distance treks, bivy camps on snowcapped summits, or dispersed camping trips a short walk from your car, and think about where you’d be happy to make compromises. Do you really need your bag to weigh less than 1kg? And do you really need a bag with a comfort rating of -22°C (-8°F) when something half as warm would do? Be honest with yourself about how you’ll use it, and let this inform the type of bag you really need. 

Oh, and one last tip: if your bag is very large, you may save space by packing it in a dry bag. These allow you to squeeze out all of the air and almost vacuum-seal it shut. You’ll be surprised at how small you can squash bags down to with this method, and as you can then mold the subsequent package into practically any shape you want, it’s way easier to manipulate into your pack. This works for both down or synthetic-filled bags.

Kelty Cosmic Down 20

The Kelty Cosmic Down 20’s is unusual in that it uses trapezoid-shaped baffles to provide insulation. The dog approves (Image credit: Kelty)

Insulation

Insulation is undoubtedly one of the biggest drivers in decisions regarding winter sleeping bags. It’s what the bag is made of, after all! And ultimately, you’ve got two options: down or synthetic. 

For years, down insulation has been considered the gold standard. Derived from the plumage of ducks and geese, it offers incredible warmth for the weight, and packs down smaller than any other insulation on the market. This makes down bags more packable and lighter on average than most synthetically-filled bags out there, though they do tend to be pricier. When it comes to down, pay attention to the “fill power”, which is a reasonable indicator of down quality. It relates to the loftiness of the down itself, and generally speaking, the higher the number, the better the quality (with 900 fill power being the best you can get). 

Unfortunately, however, down comes with one clear disadvantage: its performance when it gets wet. Despite the best efforts of the outdoor industry, be it in the form of hydrophobic or Teflon coatings, the feathers will still lose their loft when they get damp and thereby lose much of their ability to keep you warm. This is where synthetic insulation excels and is often the better choice for wet or humid environments, despite being heavier and less packable (in general).

Slumberjack Ronin -20

The Slumberjack Ronin -20’s hood in action (Image credit: Slumberjack)

Hoods and baffles

One clear difference when it comes to 4-season bags is that they will almost always come with hoods and baffles. Rectangular bags that don’t cover your head might be fine during the warmer parts of the year, but in the winter you really need a bag in which you can properly batten down the hatches. That’s why winter bags almost always come with hoods that can be cinched down tightly around the head. 

As zips can allow for heat to escape, a good winter bag will also come with baffles along the length of the zip that seal everything in once it’s closed. A baffle will often be present around the shoulders to cinch down and tighten everything up, thereby preventing any heat from escaping through the night. 

Combine with a good sleep system

One last thing to bear in mind is that a good sleeping bag is only the start. You can have the warmest sleeping bag on the market, but if you don’t combine this with a good sleeping pad or camping mattress and a proper shelter, you’ll still struggle to keep warm in the winter. 

Craig Taylor

Growing up just south of the glorious Brecon Beacons National Park, Craig spent his childhood walking uphill. As he got older, the hills got bigger, and his passion for spending quality time in the great outdoors only grew - falling in love with wild camping, long-distance hiking, bikepacking and fastpacking. Having recently returned to the UK after almost a decade in Germany, he now focuses on regular micro-adventures in nearby Snowdonia and the Brecon Beacons, as well as frequent trips to the Alps and beyond. You can follow his adventures over on komoot (opens in new tab), or visit www.craigtaylor.co (opens in new tab) for more info.