A sleeping bag liner is an unglamorous piece of kit – but an essential one. It’ll protect your expensive sleeping bag from sweat, rips, scuffs and muddy camping stains, adding years to its life. And it’ll provide a bonus layer of warmth and comfort to your backcountry sleeping experience, whether you’re wild camping in the Lake District or bothying across Scotland.
In hot weather a liner can take the place of a sleeping bag altogether, providing a thin, airy cover that won’t be too stifling – particularly useful if you’re hostel-hopping across southeast Asia.
In colder climes, a liner will boost the warmth of your sleeping bag with an extra bit of snuggly cosiness – but take brands’ claims that it’ll “add a season” to your bag with a pinch of salt. The temperature uplift will be noticeable, but perhaps not that strong.
Another key selling point of the humble sleeping bag liner is that it’s easy to wash at home, meaning you won’t have to risk washing (and ruining) your down sleeping bag.
Silk liners are the lightest, most compact and (for some) the comfiest, but they are expensive. Cotton and polycotton liners are cheaper and slightly heavier and bulkier, yet still cosy – akin to your bedsheets at home – while fleece-lined liners are the warmest.
For wild camping and long-distance walking, silk is the best choice. For overseas backpacking, a simple cotton liner should suffice, or for wintry adventures, a fleece-lined liner will provide the maximum temperature boost.
Some liners are rectangular, others have a mummy shape – it’s best to choose one that’ll match the profile and measurements of your sleeping bag to avoid excess fabric bunching up.
Sadly, there were no mountains in our field tests. Due to coronavirus restrictions, we camped in the wilderness of the back garden. Yet several nights under canvas still enabled us to test a broad spectrum of sleeping bag liners to suit all needs, and we’ve graded them in terms of performance, functionality, design and price.
Here are the results – our top sleeping bag liners that’ll guarantee a good night’s sleep, whether you’re in a tent, campervan or far-flung backpacker hostel.
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Rab silk ascent sleeping bag liner
For off-grid adventures, this is the best sleeping bag liner out there. It weighs a minuscule 120g (including stuff sack), packs down to the size of a coke can and feels silky smooth (obviously) against the skin. There isn’t much of a warmth boost and you will slip and slide around a little once inside, but that’s just nit-picking. Made from 100 per cent silk with a mummy cut, this Rab liner features a minimalist yet technical design at the lowest weight possible. We found it soft, cosy and gossamer thin, and loved the way it fitted into the smallest of backpack pockets.
Sea to Summit thermolite reactor
There’s a lot to love about this sleeping bag liner: duvet-like comfort, impressive warmth boost, nifty draw-cord at the neck for locking in heat, and a lightweight and compact design. It’s made from thermolite, a synthetic fabric that insulates you by trapping air and wicking away moisture – and it works excellently. We found the mummy-shaped liner soft and snug, with a nice stretchy feel to it, and for the 248g weight, it supercharged our sleeping bag’s warmth really well.
We also loved the colour coding at the hem for easy identification of the entrance – something surprisingly tricky to do when you’re exhausted and trying to squirm into your tent sleep system. Sea to Summit claim the liner adds eight degrees to your bag’s performance and, while that seems a slight exaggeration, the warmth-to-weight ratio is certainly top-notch. You also get a handy 15cm x 10cm stuff sack.
Snugpak fleece liner with zip
Imagine your cosiest fleece jacket – the one that feels like a big hug as soon as you pull it on – got turned into a sleeping bag liner, and that’s what you get with this Snugpak product.
It’s a liner with big pros but also big cons, so you need to know the details. Warmth wise, it’s unbeatable. The 100 per cent polyester fleece fabric is thick, super soft and so warm it almost feels like a sleeping bag in its own right. Snugpak claims it “instantly adds over a season to your sleeping bag”, meaning a three-season bag would be suitable for winter, or a lightweight two-season bag would be upgraded for autumn use. We loved the temperature boost on a chilly March night in Cumbria, while the full-length zip was great for fine-tuning breathability and comfort.
But we definitely didn’t like the 1kg weight (that’s heavier than most of our sleeping bags), humongous packed size and the excessively large entrance that’s tricky to cinch in. Yet if you’re not carrying it too far and bonus warmth is your priority, this is still an excellent choice: warm, thick and deliciously soft.
Thermarest sleep liner
Thermarest are a big name in the sleeping bag and sleeping mat market, so it only seems right that they’ve also designed an excellent sleeping bag liner. Made from brushed and embossed polyester, which is soft to the touch, this liner comes in small, regular and long sizes for a bespoke fit to your body. The regular weighs 310g, packs down to 23cm x 12cm and is machine washable. You get a pretty decent warmth upgrade – three degrees, according to the brand – and the liner works well as a standalone sheet in warmer climates. We particularly liked the three-quarter-length zip, which made getting in and out of the liner easy and enabled better temperature regulation overnight. But our favourite feature was the way the liner seamlessly integrated with our Thermarest vesper 20F quilt via sewn-in loops, creating a super-snug sleep system.
Mountain Warehouse microfibre mummy sleeping bag liner
Costing less than a tenner, this no-frills sleeping bag liner is superb value. It’s ideal as a hostel travel sheet and works just as well as a thin, protective layer for your sleeping bag. Made from 100 per cent polyester microfibre, it has a mummy cut with enough room for some night-time tossing and turning, and it feels almost silk-like against your skin.
We found it amply comfortable – particularly the extra fabric for your head to rest on – and all-around performance was impressive for the price. We didn’t notice much of a warmth upgrade from the liner, but that was to be expected considering the lightweight build. It clocks in at just 215g and packs down to the size of a pencil case.
Easy Camp travel sheet mummy
Soft, comfortable, lightweight, compact and machine washable – that’s all the boxes ticked with this affordably priced liner from Danish brand Easy Camp.
There’s not a lot else to say, really. It does its simple job well, keeping you cosy and your sleeping bag well-protected. Made from 80 per cent polyester and 20 per cent cotton, there’s a gentle mummy-style tapering to the cut and the inner gives a slight (but far from opulent) warmth boost. The liner weighs 240g and packs down to 15cm x 7cm inside a mini carry bag – ideal for stashing in your backpack and forgetting about until you need it. For £15, it’s a solid choice for hostel breaks, campsite camping and even off-grid adventures.
Outwell cotton liner single
There’s nothing quite like that safe, warm, cosy feeling of your own bed – and if you want to replicate that on the road, your best bet is a rectangular cotton or polycotton liner. The sensation against your skin will be similar to that of your bed sheets and duvet covers at home, while the rectangular cut won’t constrict you like some tight mummy liners do.
This Outwell polycotton liner (80 per cent polyester, 20 per cent cotton) features a third-length zip for easy access and ventilation, and snap button attachment to Outwell’s range of sleeping bags. We found it perfectly comfy and would definitely pack it for a hostelling holiday. It weighs 400g and packs down to 22cm x 10cm.
Decathlon silk trekking bag cover
If you want a silk liner, but the £50+ price tag for the Rab ascent puts you off, this is the budget alternative for you. And, unless you’re some sort of silk savant or liner connoisseur, you probably won’t notice much of a difference between the two. Like the Rab liner, this Decathlon offering is made from 100 per cent silk, packs away very compactly and weighs next to nothing (at 110g, it’s actually 10g lighter than the Rab). The warmth uplift – quoted as 1.5-2C – isn’t anything to write home about, but the all-around performance is good.
We found the sleek, delicate inner amply comfortable for a good night’s sleep, while the mummy cut was snug without feeling restrictive. The liner comes with a lightweight carry bag and is machine washable.
The verdict: Sleeping bag liners
For its premium performance, lightweight construction and ultra-compact packaging, the Rab silk ascent sleeping bag liner is our best buy. If you need a toasty warmth boost, our recommendation is the Sea to Summit thermolite reactor, or if you’re off hostel-hopping on a round-the-world adventure, we’d suggest the bargain Mountain Warehouse microfibre mummy sleeping bag liner.
For more home comforts while exploring the big outdoors, check out our round-up of the 9 best air beds that are comfortable, durable and great for camping
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