Our top-rated 3-season sleeping bags of 2025 – expert reviews for every camper

At the time of writing (7 May 2025), we’d say this is the best three-season sleeping bag of the year. It’s superlight, very warm and meticulously designed. 

It weighs just 690g/1lb 8oz in the regular size, which makes this bag the lightest in our 2025 group test. It’s very packable as well, compressing down to 25x16cm inside its rolltop bag. 

The Xenith III uses luxury 900-fill power down, plus a superlight 10D Plasma shell fabric. As a result, this sleeping bag offers maximum warmth for minimal weight.

Unlike most three-season bags, it features box wall longitudinal chest baffles and slanted main body baffles, which keep the fill exactly where it’s needed for optimal thermal efficiency. 

It outperforms most ultralight bags in terms of comfort. The Xenith III has a full length zip as well as a multi-panelled footbox, hood and integrated draught collar. The mummy-shaped fit doesn’t feel restrictive. 

With EN/ISO temperature ratings of -2°C (comfort) and -8°C (limit), the Xenith III is a standout choice for UK hill and mountain use from early spring to late autumn. The only downside is the price tag, but we’d say it’s worth it.

Read our Mountain Equipment Xenith III review here.

Rab’s Neutrino sleeping bags have a longstanding and stellar reputation. Hand-filled in Derbyshire, they now feature PFC-free DWR treatments and more recycled materials. In addition to the standard temperature ratings, the Neutrino 400 also has a ‘Rab Sleep Limit’ of -7C based on Rab’s “real-world assessment of a sleeping bag's useable temperature limit”.

Insulation is provided by 400g of high-lofting 800 fill power European goose down, and you’ll be hard pushed to find a bag with a better warmth-to-weight ratio. Rab uses down with Nikwax’s hydrophobic fluorocarbon-free finish, ensures it dries quicker, absorbs less water, and retains its loft better when damp.

The tapered mummy design has a narrow, tight cut. Some may find it too restrictive, but it does help eliminate cold spots and maximise thermal efficiency. It also keeps packsize and weight to a minimum. An adjustable neck baffle has a close fit designed to decrease any heat loss, and the hood can be cinched in for a fine-tuned fit.

The ¾ length YKK main zipper has a synthetic filled baffle to trap warmth, while a small zippered internal stash pocket provides useful for storage. All the zippers have anti-snag guards to help prevent the zipper ‘catching’ on the liner or shell.

Check out the women's version here

Read our full Rab Neutrino 400 review

In terms of bulk, weight, performance, and price the Apex 3 is quite similar to the Robens Glacier III -9C. They're both synthetic-insulated 3-season sleeping bags rated for the low negatives and both with a good price.

The Apex 3 is a more aggressive mummy shape than the Robens, and arguable a tad warmer because of that. Overall, it's a comfy fit, but only comes in one size (like the Robens), which is a bit annoying but not the end of the world.

We liked that the lining, shell, and insulation is all fully recycled (the lining and shell are made from fishing nets) and also feels nice against the skin. It's also quite durable.

The downside is that this sleeping bag is quite heavy and bulky, measuring over 40cm in length and over 25cm in width when packed down and weighing over 2kg.

Read our full Vango Apex 3 review

Near Zero might not be a household name in the outdoor industry, but 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 organisational system.

During our testing of a Near Zero bundle, we had the opportunity to test their NZ 20 sleeping bag, and it left us thoroughly impressed as a lightweight three-season option offering an impressive warmth-wot-weight ration 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 -2°C while weighing just 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 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 0°C and a lower limit of -6°C. 

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 prioritise comfort.  

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

The Mammut Comfort Down -5C has a relaxed mummy shape and a distinctive centre zip, allowing for excellent ventilation and ease of access, which is especially useful for side sleepers. 

It comes in two lengths, with a -5°C lower limit for the men’s/L size and -7°C 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. 

Stuffed with 600g of 100% recycled 650 fill power duck down and encased in recycled polyester fabrics, the bag boasts impressive sustainability credentials. However, the fill doesn’t have a hydrophobic treatment or responsible sourcing certification. 

On test, it proved to be comfortable and warm, although its generous sizing may leave excess dead space for smaller users, potentially reducing thermal efficiency.

The central zipper, dual drawcord hood, and clever 'blanket mode' add versatility to this sleeping bag. However, it misses out on features found in Mammut's premium models, such as an internal pocket or a hood lining that reduces noise.

Overall, the Mammut Comfort Down -5 is a comfortable and versatile bag with a practical centre zip and good sustainability credentials. 

Check out the women's version.
Read our full Mammut Comfort Down review here.

Minimalist backpackers and fastpackers will be particularly drawn to the Big Agnes Fly Creek UL 25 premium, ultralight three-season sleeping bag. 

Weighing just 700g (regular size) and packing down to a compact 24cm x 20cm, it offers impressive warmth for its weight, with a comfort rating of +2°C and a lower limit of -4°C. 

Its tapered mummy shape, high-quality 850 fill power Downtek hydrophobic down and diamond quilting all contribute to its excellent warmth-to-weight ratio, though the slim fit may feel restrictive for broader builds.

True to its ultralight ethos, features are minimal. It includes a snug hood, ergonomic footbox, draught collar, and a small half zip. The zip is effective but fiddly and limits ventilation. 

Sustainability is a strong point, though: the Fly Creek uses NetPlus fabric made from recycled fishing nets, a PFAS-free DWR, and bluesign-approved, RDS-certified down fill. The bag’s materials are both eco-conscious and high-performance. 

While this bag excels in weight-conscious scenarios, it may not suit those who prioritise roomy comfort or versatility in variable conditions. Retailing at £450, it’s certainly not cheap, but competitively priced for a top-tier ultralight bag. 

Ultimately, the Fly Creek UL 25 is an excellent choice for gram-counters and thru-hikers seeking serious performance in a minimalist package. However, if you’re looking for space to spread out or versatile ventilation for balmier nights, you might prefer a more feature-rich alternative.

US brand 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 1550g, 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.

Check out the women's version here

Read our full Nemo Forte 20F Endless Promise Synthetic Sleeping Bag 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.

Check out the women's version here

Read our full Sierra Designs Cloud 800 review

Sea to Summit Ascent -9C is a great all-rounder, featuring 750+ fill power down with a -2C comfort rating for a weight of 1020g. These are solid stats offering reliable warmth, particularly considering the bag only weighs a smidge over 1kg.

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 brew without leaving the warmth of your bag.

Check out the women's version here

Read our full Sea To Summit Ascent Down Sleeping Bag -9°C review

The Questar is perhaps the most affordable of Therm-a-Rest’s down sleeping bags, and its temperature ratings are excellent at this price. 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 540g, which is pretty considerable. The packed size and weight of the Questar is good, but not exceptional for a down-filled sleeping bag, so gram counters 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 maximises loft and minimises 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 your 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 Sleeping Bag review.

What we found of the Wolftrail sleeping bag (brilliant name) from Jack Wolfskin is that it's a dependable all-round 3-season sleeping bag suitable for most situations.

At about 1.5kg (for the long 195cm version we tested) and packing down to 37 x 22cm, the Wolftrail is far from the lightest or most compact option here. But on the plus side, it is more durable than the ultralight models, and with a comfort limit down to -7°C, it performs well too.

We really liked the Wolftrail's unique details such as the S-shaped SmooZip, which is very ergonomic and opens the bag wide making it easy to get in and out of. It also has a neat stash pocket next to the hood where you can put your pillow (there's a small internal security pocket too).

The Wolftrail has sound sustainability credentials too. It's PFC-free, bluesign-approved, and uses a fully recycled main fabric. Jack Wolfskin is also a Fair Wear Foundation member with 'Leader' status denoting its commitment to worker welfare.

Check out the 180cm version here

Read our full Jack Wolfskin Wolftrail Down -7 review

The Nemo Disco 15 sleeping bag is uniquely designed. It prioritises 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 prioritise comfort, particularly those who sleep on their side.

Check out the women's version.
Read our full Nemo Disco 15 review.

Compared to down bags, synthetic sleeping bags offer better value, easier maintenance, and improved insulation when wet. The synthetic fill in Robens’ Glacier III -9C is a fluffy 100% polyester known as AirThermo. This delivers a cosy sleeping experience even in sub-zero temperatures and the Glacier’s EN/ISO lab test temperature ratings are superb given the price. The downside is that the bag weighs 1795g, which is on the heavy side.

Robens has placed a higher grade of insulation on the top of the bag where you need it most. Insulation on the underside tends to be less important because you gain some warmth from your sleeping mat, plus any insulation under your body tends to be crushed and less thermally efficient. Robens’ ‘loft expander system’ separates the inner lining from the outer shell to enhance loft space and retain heat, providing enhanced warmth in the upper half of the bag.

The taper of the design is not particularly harsh, striking a nice balance between technicality and comfort. The two-way YKK zipper has a full-length insulated baffle to keep the cold out and an anti-snag guard. The hood is well designed and can be adjusted via a drawcord for a fine-tuned fit, while a thick baffle around the neck minimises draughts.

Read our full Robens Glacier III -9C review

The Sea to Summit Hamelin Synthetic sleeping bag is an affordable option for spring-summer camping, but might not be warm enough for colder nights. It’s ideal for damp conditions though, as it dries fast.

Priced at £170, it’s good value, with impressive eco credentials: 100% post-consumer recycled insulation and Bluesign-approved recycled fabrics with PFC-free DWR.

The Hamelin prioritises comfort. It has a relaxed mummy shape, with gender-specific fits. For ventilation, there’s a full-length zip and a half zip on the opposite side, letting you stick out arms or feet.

It’s heavier and bulkier than most down equivalents (1.12kg for men’s regular), but you get better durability, sustainability and versatility. 

All in all, this is an affordable, comfortable and sustainable bag that works well for mild-temperature wild camps and bivvies, as long as you don’t mind a little extra weight – and a little less space – in your pack.

Check out the women's version.
Read our full Sea to Summit Hamelin review here.