Best sleeping bags for 2025 | Tested and reviewed for all seasons

When he reviewed a load of three-season sleeping bags in May 2025, gear tester Matt Jones decided that this was the best. It’s ultralight, very cosy and well-designed.

It's the lightest of all of the bags he tested, weighing just 1lb 8oz (690g) in the regular size. It compresses to 25x16cm in its bag, which outperforms most competitors.

The Xenith III has a very good warmth to weight ratio. It's made with luxury 900-fill power down, plus a superlight 10D Plasma shell fabric – this means it's super cosy, but also very light.

Unlike most three-season bags, you get vertical chest baffles and slanted main body baffles, which maximize heat retention.

It offers superior comfort compared to most ultralight options. Features include a full-length zip, a multi-panel footbox and hood, and an integrated draught collar. The mummy-style design provides a snug fit without feeling restrictive.

With EN/ISO temperature ratings of 28°F (comfort) and 28°F (limit), the Xenith III is a standout choice for hill and mountain use from early spring to late autumn. The only drawback is it's high cost, but Matt reckons it's worth it.

Read our Mountain Equipment Xenith III review here.

Nemo is known for its innovative approach and the Forte 20F offers some unique design features. It is roomier than most sleeping bags, with more space at the knees and shoulders for a less-constricted feel.

A sleeve-like pocket for sliding in a camping pillow keeps it neatly in place, while Nemo’s ‘Blanket Fold draft collar’ – a large, thick flap of insulation – blocks cold air when tucked in, or mimics the cosy comfort of a mattress at home when folded down.

Two 53cm vents across the top of the sleeping bag, with zippers on the top and on the underside and a layer of fabric between the two, allow you to micro-adjust your temperature inside the sleeping bag.

The fill is Zerofiber PCR (100% polyester) synthetic insulation. This is a 100% recycled insulation, ensuring the bag has excellent eco credentials.

The regular length Forte weighs 3lb 7oz (1,550g), which is about par for the course when it comes to synthetic sleeping bags. The 46x24cm packed size is bulkier than ideal.

The temperature ratings are solid for a bag at this price, but the roomy fit of the Forte 20F and the subsequent risk of ‘cold spots’ means we’d suggest mostly using this sleeping bag in slightly warmer climes.

Read our full Nemo Forte 20F Endless Promise review review or check out the women's version here.

It's easy to be fooled by this lightweight sleeping bag that appears to be filled with not very much insulation. Such is the deceptive beauty of high-quality down.

The Ultra 0°C/32F uses high loft 850-fill goose down, which means you don't need much to get a warm sleeping bag. Thus, 10.4oz of fill (long size) gives the Ultra a temperature rating suitable down to about 35°F. Weighing in at 1lb 5oz (600g) for a long version of a sleeping bag, that's very impressive.

There's another big plus point to the Ultra. While most sleeping bags come in regular and long sizes, the Ultra comes in five sizes: small, medium, wide medium, large and wide large.

Furthermore, you get a very sustainable sleeping bag here, too. Naturally, the down is responsibly sourced, but the Exped Ultra 0°C/32F goes further. The Pertex Quantum outer material is recycled, as is the zip. It is a bluesign-approved product and PFC-free; Exped has even offset the manufacturing and shipping emissions.

Downsides to this sleeping bag include the trade-off with the 10D Pertex fabric. Sure, it's super lightweight and has the potential to be long-lasting, but you need to be very careful with it to achieve that. It's a tad delicate.

It's also understandable to balk at the price on initial inspection. However, you do get a lot in return.

Read our full Exped Ultra 0 review.

We're big fans of Rab's versatile Neutrino range. With 10 total products sporting various weights and materials, the 400 is a stand-out contender. Rab hasn't skipped a single detail; each bag is hand-stuffed and fully-featured, treated with a level of care that has earned the Neutrino 400 a number of top awards from us over the past few years.

Features include an adjustable hood, three-quarter length YKK zipper, angled footbox, internal stash pocket, cotton storage sack and waterproof compression sack, among others. As well as being packed with nifty features, the Neutrino 400 has a unique baffle design that solidifies its place at the top of this list.

Baffles are the individual pockets of down fill responsible for the bag's insulation. While most bags go for horizontal baffles, the chevron-style arrangement in the Neutrino 400 allows for more loft, fewer cold spots, and uses less overall material.

We're also very pleased to see some newly implemented sustainability upgrades. Rab has used PFC-free DWR treatments as well as increasing the amount of recycled materials in their construction, particularly in the Pertex Quantum shell.

Read our full Rab Neutrino 400 review or find the women's version here.

This Arizona-based brand caught our attention with its ready-to-hike bundles that neatly pack into the brand's 55-litre backpack, featuring a unique internal organizational system.

During our testing of a Near Zero bundle, we had the opportunity to test the NZ 20 sleeping bag, and it left us thoroughly impressed as a lightweight three-season option offering an impressive warmth-to-weight ratio and good value.

Insulated with 850-fill power down and a remarkably lightweight 10D nylon shell fabric, the NZ 20 boasts a comfort temperature of 28°F while weighing just 1lb 12oz (800g) in its regular size variant.

The very high quality of the down ensures excellent loft, though some may find the mummy fit too restrictive. However, Near Zero offers three different sizes to accommodate various heights.

The trade-off of its impressively low weight is that shell and lining materials do feel quite delicate and demand careful handling for longevity. Nonetheless, its impressive performance and relatively affordable price make it a standout choice in the market of lightweight sleeping bags.

Read our full Near Zero bundle review.

The Big Agnes Fly Creek UL 25 is a premium, ultralight three-season sleeping bag. 

It offers impressive warmth for its weight. The regular size is just 1lb 9oz (700g) and packs down to a compact 24x20cm, yet it's rated to 35°F comfort.

The Fly Creek has a slim tapered shape, with high-quality 850-power down and diamond quilting. It should be noted that the slim fit may feel restrictive for broader builds.

Unsurprisingly for an ultralight bag, features are minimal. There's a snug hood, ergonomic footbox, draught collar and a small half zip. The zip is effective but fiddly; the fact it's only goes half the way down limits ventilation. 

It's wonderfully sustainable, though. The Fly Creek uses NetPlus fabric made from recycled fishing nets, a PFAS-free DWR, and bluesign-approved, RDS-certified down fill.

While this bag is excellent for ultralight camping, it may not suit those who prioritize comfort or versatility in varied weather conditions. It's competitively priced for a premium bag, but it's certainly not cheap ($499.95 RRP).  

Read our full Big Agnes Fly Creek UL25 review.

The Mammut Comfort Down -5C is particularly useful for those who sleep on their side. It has a relaxed mummy shape and a distinctive centre zip, enabling excellent ventilation and ease of access.

It comes in two lengths, with a 23°F lower limit for the men’s/L size and 19°F for the shorter women’s/M size. It performs well in terms of warmth to weight and packability, though it can’t compete with higher-spec bags. 

It's pretty sustainable, with with 1lb 5oz of 100% recycled 650 fill power duck down and recycled polyester fabrics, though there's no responsible sourcing certification. There's no hydrophobic treatment, which might make it less durable in the long run.

It's generously-sized, so smaller users might find that there's too much dead space inside – this reduces thermal efficiency. But for Matt on test, it proved to be comfortable and warm.

The Mammut Comfort Down is certainly versatile, thanks to the central zipper, dual drawcord hood, and 'blanket mode'. But Matt finds that it's not as 'premium' as other Mammut models, as there's no internal pocket or noise-reducing hood lining.

Overall, the Mammut Comfort Down -5 is a comfortable and versatile bag with a practical centre zip – we'd say it's a great all-rounder.

Read our Mammut Comfort Down review here.

The word ‘innovative’ gets thrown around a lot in outdoor kit reviews, but in this case it seems warranted. The Therm-a-Rest Boost 650 is a cleverly designed bag, with impressive comfort and versatility.

Its most unique feature is the central 'WarmZip' baffle, which transforms the bag from a roomy, semi-rectangular shape into a snug mummy-style fit for better thermal efficiency in colder conditions. 

There’s some more useful features, like a snug hood, arm holes, and internal pocket. The arm holes mean that you can stick your arms out, without leaving the warmth of your sleeping bag. The Boost stands out for its inclusive sizing, with multiple lengths and widths to suit various body shapes.

Filled with responsibly sourced 650 fill power duck down treated with a hydrophobic, PFC-free finish, the bag offers a comfort rating of 32°F and a lower limit of 20°F. 

We’d say it’s suitable for backpacking, though there are lighter and more compact options out there. The Therm-a-Rest Boost 650 is more luxurious than ultralight, so it’s ideal for those who prioritize comfort.  

Read our full Therm-a-Rest Boost 650 review.

This sleeping bag is a maverick. There’s no zip, but the bag still opens wide thanks to a curved, wraparound ‘comforter’ – a duvet-like flap that pulls over your upper body.

A big overlap between the comforter and the bag’s edge prevents draughts, while the zipperless design makes getting in and out easy and delivers a sensation akin to your bed at home.

Insulation is provided by 800 fill power goose down, housed in chunky box-wall baffles. However, all the insulation is over the top and sides of the body – there’s no down whatsoever on the underside.

The logic is that any down on the under your body will be squashed, lose its loft, and be ineffective as insulation. Instead, there’s a sleeve to accommodate your sleeping bag, but you will need a well-insulated mat with a decent R-value to guarantee you stay warm.

This approach does keep the weight down though, and the temperature ratings suggest the warmth-to-weight ratio is excellent. However, the design and lack of hood drawcord does mean that cold spots may be a problem, so it’s best not to push the limits of the bags cool weather performance. Plus, its ease of ventilation makes it better suited to milder temperatures.

Read our full Sierra Designs Cloud 800 review for more or check out the women's version here.

Sea to Summit Ascent 15F is a great all-rounder, featuring 750+ fill power down with a 29F comfort rating for a weight of 2lb 4oz (1,020g). These are solid stats offering reliable warmth, particularly considering the bag's weight.

The insulation is 750+ fill power goose down, housed in chunky box-wall baffles. This is not bad, but neither is it exceptional, and given the high price of the Ascent we might have expected a higher grade of down.

An Ultra Dry Down treatment has been applied to the insulation, which helps improve water resistance, ensuring it performs better and retains its warmth and loft, even in humid and damp conditions.

You get a fitted hood, a chunky draught collar, and a down-filled draught tube covers the two-way zippers (full-length to the toe box on one side and a half-length zipper on the other side) to keep the cold out and the heat in.

The dual zipper design means the bag vents brilliantly and that you can get your arms out to sort gear or make a coffee without leaving the warmth of your bag.

Read our full Sea To Summit Ascent Down Sleeping Bag -9°C review or check out the women's version here.

The Questar is perhaps the most affordable of Therm-a-Rest’s down sleeping bags and its temperature ratings are excellent at this price (a comfort temp of 32°F and a limit of 20°F).

The insulation is 650 fill power duck down, and while this is not a particularly high quality of down (other bags use 700, 800 or even 900 fill power) there’s a lot of it; the fill weight is 1lb 3oz (540g), which is pretty considerable.

The packed size and weight (2lb 3oz in size regular)of the Questar is good, but not exceptional for a down-filled sleeping bag, so lightweight backpackers may want to look elsewhere.

The tapered, mummy-shaped design is technical but generous, providing extra wriggle room compared to some other bags. The box baffled construction maximizes loft and minimizes cold spots, while zoned insulation improves the warmth-to-weight ratio, with 60% of the insulation is placed on the top and sides (where you need it most) and 40% on the underside.

Therm-a-Rest’s SynergyLink system features two ultralight straps that connect the sleeping bag to your sleeping mat, ensuring you don’t slide off it and improving thermal efficiency.

Other features include a heat-trapping draught collar at the neck, a full-length zipper draught tube, snag-free main zipper, cinchable hood and external zip pocket, as well as a super-cosy down-lined footbox (Therm-a-Rest’s wonderfully named ‘Toe-asis’).

Read our full Therm-a-Rest Questar 20F/-6C Down review.

The Marmot Trestles Elite Eco sleep bags have consistently impressed us with their combination of high performance and reasonably sustainable materials.

The Trestles Elite Eco 30 has a temperature rating of 32°F, which makes it useful for a wide range of scenarios. It's made from fully recycled materials throughout, including the innovative HL-ElixR Eco insulation.

For a synthetic sleeping bag it offers an very good warmth-to-weight ratio and maintains insulation even when damp – a hallmark of synthetic materials.

The Trestles Elite Eco 30 is also compact, certainly for a synthetic sleeping bag. It has a full-length main side zip that resists snagging and an additional zip on the opposite side for improved ventilation and ease of access.

Inside the bag, you'll get plenty of space for a hiking sleeping bag, especially in the foot area, setting it apart from traditional mummy-shaped designs. The hood cinches snugly around the head, enhancing comfort during colder nights.

While there are some minor points to consider, such as the main side zip not extending fully to the foot, resulting in warmer feet even when partially open, and the shoulder baffle being slightly less effective compared to some competitors, these are relatively minor concerns rather than significant drawbacks.

Overall, the Marmot Trestles Elite Eco stands out as a top choice for those seeking both performance and eco-conscious design in a synthetic sleep bag.

The Nemo Disco 15 sleeping bag is uniquely designed. It prioritizes space to spread out thanks to its distinctive ‘Spoon’ shape, which is ideal for side sleepers. 

Available in men’s and women’s sizes with generous dimensions, the Disco 15 is suitable for use from spring to late autumn. Its standout features include a pillow pocket, Thermo Gills for adjustable ventilation, a cosy Blanket Fold collar and waterproof panels at the hood and footbox to protect against moisture. 

Ethically made using RDS-certified hydrophobic down and 100% recycled fabrics, it also supports full recyclability through Nemo's ‘Endless Promise’ initiative, giving it strong sustainability credentials. 

However, the extra comfort and well-designed features come at a cost: it’s heavier and bulkier than many ultralight options, and its roomy build makes it slightly less efficient at retaining heat.

So, while it might not suit ultralight enthusiasts, the Nemo Disco 15 is a solid pick for environmentally-minded campers who prioritize comfort, particularly those who sleep on their side.

Read our full Nemo Disco 15 review here or find the women's version here.