Best lightweight sleeping bags 2024 | Tested and reviewed

The Sea to Summit Spark SPIII has been our go-to lightweight sleeping bag for a few years now. In truth, it's retiring in 2024 as Sea to Summit overhauls its sleeping bag range. But for now, the Spark SPIII remains widely available and still our favourite.

Why? Partly because it has one of the best warmth-to-weight ratios on the market, thanks to high quality 850-fill goose down and ultralightweight 10D shell and lining fabrics. But largely its down to comfort because unlike most top end sleeping bags with their highly tapered mummy shapes, the Spark SPIII is noticeably more roomy.

This sleeping bag isn't overloaded with features but has the important stuff like a two-way zip and easy-cinch hood. So, in recognition of its excellent design, we bid the Spark SPIII adieu with a final Gear of the Year award.

Read our full Sea to Summit Spark SPIII review

For those after a superb warmth to weight ratio, the alpine-style Neutrino family of sleeping bags have long been favourites. The Neutrino sleeping bags are available in five fill weights (not including the Neutrino Pro models), and the 400 is the second lightest.

It’s our pick of the bunch because it offers a comfort rating of -1°C while weighing less than 800g (regular size) and packing down to just 35cm x 23cm.

Key to its success is its shape and quality of fill. It uses 800-fill power goose down and is a highly tapered mummy shape to be as thermally efficient as possible. This does mean that it feels pretty restrictive to lie in – side sleepers and movers probably won’t like it, but others may find it very snug and cocooning.

The Neutrino 400 comes in three sizes and a women’s version, which has a slightly different shape. In terms of features, there are plenty. All the zippers have anti-snag guards; there is a small internal stash pocket for items such as a headtorch; and the chevron shaped baffles help the down for fully loft.

This sleeping bag has good eco credentials too. Its main fabrics are fully recycled, it’s PFC-free, and Rab is a Fair Wear Foundation member with ‘Leader’ status.

Women's version here

Read our full Rab Neutrino 400 review here

The PipeDream 200 is the lightest model in Alpkit’s PipeDream line. It’s a reasonably basic option with only a couple of additions such as the use of DownTek hydrophobic down.

But on the plus side, the bag packs down to a tiny 15cm x 12cm and weighs less than 600g (the regular size weighs just 545g). It’s therefore a brilliant summer sleeping bag for hikers – especially for those favouring a lightweight minimalist approach.

In terms of fit and comfort, the PipeDream 200 is a mummy shape, but isn’t quite as severely tapered as the Rab Neutrino sleeping bags. The 200 has a comfort rating of around 7°C so be in no doubt this is a bag for mild conditions – but there are 400 and 600 versions of the PipeDream that are rated for negative temperatures. You could also couple it with a sleeping bag liner.

The 20D material used isn’t recycled but the DWR and hydrophobic down are both PFC-free. Alpkit is also a certified B Corp.

Designed to offer impressive synthetic performance while using the most sustainable materials it can, the Marmot Trestles Elite Eco models have been among our favourite synthetic sleep bags for several years now.

It uses a fully recycled synthetic insulation called HL-ElixR Eco, which offers an impressive warmth to weight ratio and continues to insulate when damp (a trademark of synthetic insulation). The shell and lining materials are also fully recycled.

In addition to the low weight, the packed size of the bag is good for a synthetic with this temperature too. The main side zip is full-length and exceptionally well designed not to snag, but there’s also an additional zip on the opposite side of the bag so you can more easily vent the top, as well as sit and read from the bag.

Get in the bag and it is more spacious than most highly tapered mummy shaped models, with a particularly roomy foot area. The hood draws in easily and is very comfortable around the head.

Drawbacks? The main side zip doesn’t quite reach the foot either, so you do get warm feet even with the zip open, although that is a minor difference perhaps rather than a big drawback. There is a shoulder baffle but compared to some it is not quite as good at locking in the warm air. So, perhaps niggles rather than drawbacks.

Check out the women's version here

This sleeping bag from Exped is remarkable in its combination of lightness and warmth. The answer lies in its premium 850-fill goose down insulation, efficient mummy shape, and lightweight fabrics, enabling this 600g sleeping bag (long size) to achieve a comfort temperature rating down to approximately 2°C.

Unlike many other sleeping bags that typically offer only regular and long sizes, the Exped Ultra 0° comes in five variations: small, medium, medium wide, large, and large wide.

What also sets the Exped Ultra 0° apart is its commitment to sustainability. While responsibly sourced down is expected of all sleeping bags, Exped takes it further by utilising a fully recycled and bluesign-approved 10D Pertex Quantum outer fabric with a PFC-free, plant based DWR. The zipper is made from recycled bottles too. Exped even offsets manufacturing and shipping emissions.

Although it does have potential for longevity, be aware the the Ultra 0 should be used and handled with care due to the delicate nature of the shell and lining fabrics.

Read our full Exped Ultra 0 review

Near Zero is unlikely to be an outdoor brand you’ll know. It’s reasonably fresh, based in Arizona and specialises in ready-to-hike bundles that fit into its 55-litre backpack with a unique internal organisation arrangement.

We tested the brand’s NZ 20 sleeping bag while we were testing a full Near Zero bundle and were really impressed by it as a lightweight 3-season sleeping bag.

It uses very high quality 850-fill power down, which in combination with a super lightweight 10D nylon shell fabric means the NZ 20 has a comfort temperature of -2°C at a weight of just 800g (regular size).

That’s impressive, and even more so considering this bag’s price. The untreated down lofts really well, and while the fit is snug (some would say restrictive), there are three different sizes to suit body types.

Like the Therm-a-Rest Parsec 0F (below), the NZ 20 does feel quite delicate and does need to be treated carefully if you want to ensure longevity.

Read our full Near Zero bundle review here

Therm-a-Rest's Parsec -18°C sleeping bag continues to be a standout for us because it delivers on all fronts: warmth, comfort, weight, and sustainability.

Weighing in at a mere 1kg (1.1kg for large size) and a comfort rating of -10°C, the Parsec boasts a remarkable warmth-to-weight ratio thanks to its innovative 'heat-mapped zoned insulation'. By strategically placing 70% of the down on top and 30% below, it achieves superior temperature ratings compared to similar products on the market.

Its eco-conscious design features a 100% recycled ripstop nylon DWR shell and liner, PFC-free hydrophobic down treatment, and of course RDS down. In terms of features, our favourite is the 'synergy link' connectors, which let you strap your bag to your sleeping mat.

Additional highlights include the plush 'toe-asis' footbox and effective heat-trapping draft collars and baffles. You of course get compression and storage stuff sacks as well.

However, due to the lightweight fabrics and construction, the Parsec feels a bit delicate and long-term durability, particularly under heavy outdoor use, is questionable. Additionally, the premium price tag may deter budget-conscious buyers, and the Parsec's temperature ratings may be excessive for milder winter conditions.

Sea To Summit’s Ascent sleeping bags don’t offer the pinnacle of warmth-to-weight ratios. With the Ascent -1°C, it weighs around 800g and has a comfort rating of 3°C – that’s good but not the best.

The Ascent -1°C makes up for it though, thanks to quality of design. The hood, for example, is generous but is adjustable and can be cinched in tighter. You also get a very clever zip arrangement.

The main zip is full length and two-way, but there is another half-length zip on the other side. This gives you far for ventilation options – half unzipped and folded on a hot night, unzipped and the feet or anywhere really. This arrangement also allows you to wear the sleeping bag with your arms free so you can use your stove for example.

The fit is more relaxed than many other lightweight sleeping bags, with noticeably more room to move as a result. Sea to Summit calling the shape a ‘relaxed mummy fit’, meaning it sits in between mummy and rectangular.

Check out the women's version here

We first tested this super affordable synthetic sleeping bag five years ago, and remains a great option for summer. Granted, it’s the heaviest option in our selection but at 1.3kg it’s still pretty lightweight, and it packs down to about 38cm x 23cm – again, the bulkiest option here but still reasonably compact.

The Roam 200 features a ¾-length zip, internal stash pocket, and anti-snap zipper. It’s therefore pretty basic but for the price, that’s not too surprising.

The Roam 200 is pretty comfortable though, thanks to the soft lining material. It is a tapered mummy shape, but there’s still room to move.

There’s nothing really to discuss regarding sustainability, which is disappointing – using recycled materials is expected with synthetic outdoor gear these days.

This particular sleeping bag liner is the lightest and most effective means of boosting your sleeping bags warmth. It's made using a partially recycled Thermolite Pro fabric and is designed to boost warmth by 12% on a summer sleeping bag and by 6% in a 3-season one.

On paper that sounds negligible but anyone who's used a thermal sleeping bag liner before can testify how well they work.

What makes the Reactor Liner our favourite of all it that it's super lighter and more compact than most thermal liners, weighing a mere 268g, packed into a tiny 15 x 11cm package. It also has a bio-based anti-odour treatment.

There is a family of Sea to Summit Reactor liners, with this being the lightest. There are also Reactor Extreme and Rector Fleece versions that boost warmth even more.