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By: Andrew Forrest - July 2025
Sleeping bag liners may seem simple, but they are among the smartest upgrades you can add to your sleep system. They provide extra warmth, enhance comfort, and keep your sleeping bag clean - all in a lightweight, packable design.
Whether you're camping in the UK, staying in a hostel or hotel, or even using it at home, the right liner makes every night more comfortable. For those hot nights, it can even be used on its own. In this guide, we'll explain why sleeping bag liners are a must-have for outdoor enthusiasts and how to select the perfect one for your next trip.
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A sleeping bag liner is just one part of your overall sleep system, which also includes your sleeping bag and sleeping mat. Each plays a key role in keeping you warm, dry, and comfortable through the night.
While your sleeping bag offers the primary insulation and your mat prevents heat loss to the ground, a liner adds an extra layer of warmth, enhances hygiene, and boosts comfort. Choosing the right liner can make your entire setup more versatile, extending your sleeping bag's range or providing a standalone option for warm nights.
Below, we've reviewed some of the best sleeping bag liners to help you find the ideal one for your next backpacking or camping trip. The liners we've chosen are not always the most expensive; we've selected them based on overall value, considering factors such as price, features, comfort, warmth, pack size, functionality, and durability.
The Sea to Summit Silk Blend Liner combines the luxurious softness of silk with the insulation benefits of Thermolite synthetic fibre. With 28% silk, it feels smooth and breathable, while the 72% Thermolite adds warmth and durability without bulk. Its stretchy side panels enable comfortable movement during sleep. Overall, this was my standout hybrid liner.
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Description:
The Sea to Summit Silk Blend Liner combines the luxurious feel of silk with the added insulation of Thermolite synthetic fibre. The 28% silk content feels soft and breathable, while the 72% Thermolite enhances warmth and durability without adding much bulk. Sea to Summit states it increases the sleeping bag's temperature rating by 5% for a 3-season sleeping bag and 8% in a 1-season bag.
Its stretchy side panels allow for freedom of movement during sleep, solving a common problem with tight-fitting liners. The mixed fibres create a finish that is less shiny than pure silk. The seams are double-folded and reinforced for durability.
HeiQ Fresh treatment helps keep the liner smelling fresh over several nights. Plus, it is ultra-lightweight, and the compact stuff sack makes it ideal for minimalist backpacking and warm-season travel.
I tried it earlier in the spring when the extra warmth made sleeping in my lightweight sleeping bag comfortable, and recently, it has been used a couple of nights in warm weather on its own. It feels almost as soft as pure silk, but with some added warmth, and the Rectangular and Mummy versions mean there is an option for everyone. If you are looking for that silk feel with a bit of extra warmth, then this could be the liner for you.
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This mummy-shaped thermal liner is our Walks4all top thermal choice due to its combination of lightweight design, compact size, and excellent warmth, which enhances your sleep setup. Often called the 'summit reactor', this liner is renowned for providing extra warmth and is popular among outdoor enthusiasts. It's a versatile option for hikers, backpackers, and anyone looking to add extra warmth to a sleeping bag without a significant weight increase.
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The Thermolite Reactor is widely seen as one of the best sleeping bag liners available, and for good reason. Its lightweight Thermolite fabric has a soft, plush, fleecy feel that is gentle against the skin but much lighter and more packable than standard fleece. Thermolite also includes Lycra, allowing the liner to stretch and move with you as you move around during the night.
For me, this liner is very effective at trapping body heat. By reflecting your body heat back, it genuinely enhances the rating of your sleeping bag, making it ideal for extending the season into colder nights.
Despite its warmth, the Reactor remains relatively lightweight, weighing at 268 g, and folds into a compact stuff sack roughly the size of a 1-litre water bottle. This warmth-to-weight ratio is excellent, making it appealing to backpackers and outdoor enthusiasts who need to keep pack weight low.
The mummy-shaped design, featuring a drawstring hood, ensures minimal dead space, maximising thermal efficiency. The build quality is excellent - the liner is well-made and durable for polyester. It's easy to wash and dries quickly, making it convenient to clean after a trip.
One of the major advantages for me is its versatility. There is a drawcord at the bottom that keeps the warmth in when pulled tight, but can also be loosened to let cooler air in if you become too hot. Another benefit I find is that if you need to visit the loo in the night, you can simply lift the liner up around your waist while still 'wearing' it.
They may not be suitable for everyone, but these also feature arm openings. I find that my arms get too hot when inside a liner and sleeping bag, and I also feel restricted, so these arm openings help with that. I find that they are also useful when reading, as it is easy to hold a book or a map.
There are three versions of this reactor liner. A compact version with a drawcord for the hood (268 g), which is suitable for people up to five feet nine inches (175 cm), and a standard version, which is seven inches longer and weighs 284 g, or 265 g without the drawcord.
If you like the sound of this reactor liner, they produce two warmer versions of it, with all functionality remaining exactly the same. The Sea to Summit Reactor Extreme Liner is orange and black in colour and adds up to 15% more warmth to a one-season sleeping bag and up to 7% extra warmth to a three-season one. It is available in both standard and compact versions and weighs around 350 g.
The warmest of all is the Sea to Summit Reactor Fleece Liner, available in orange and black. It provides up to 22% more warmth for a 1-season bag and up to 10% extra warmth for a 3-season sleeping bag. Like the other two, it is available in standard and compact versions, but this time it weighs approximately 400 g.
Overall, an excellent thermal liner that keeps your sleeping bag clean, is comfortable, adds warmth and can be used on its own in summer.
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In summary, the Sea to Summit Thermolite Reactor ranks among the top liners for those seeking quality, performance, and dependable insulation to add warmth to any sleep system.
Silk liners are my preferred choice for summer camping, and this silk sleeping bag liner from Lifeventure is an ultra-lightweight and breathable option that can be used alone or together with a sleeping bag for extra warmth. Silk naturally helps regulate body temperature and efficiently wicks away perspiration.
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The Lifeventure silk liner is ideal for travellers and backpackers seeking a super lightweight, compact liner that feels luxurious against bare skin. It enhances comfort without adding noticeable weight or bulk to your pack.
Its silk fabric helps wick moisture and keeps fresh longer, making it perfect for warm nights or multi-night trails. It is available in both rectangular and mummy shapes, allowing it to fit various types of sleeping bags. Silk always feels extremely smooth on my skin and seems to keep me cooler than any other type of liner.
On hot nights, I use this silk liner alone without the sleeping bag. Its compact size makes it perfect for packing in luggage during trips, so you can always have a clean and comfortable liner ready. If pillow holders are your thing or you want something that may help keep unwanted smell build up away over longer trips, for not too much more, you can also buy the Lifeventure Ultimate Silk Liner, which is also available in mummy and rectangular shapes.
The Lifeventure Ultimate Silk Liner is the same liner but features an integrated pillow sleeve and is treated with Polygiene, which helps it stay fresher for longer. It also has a concealed 'passport' pocket. Despite its lightweight design, it is well-made with reinforced seams and includes Polygiene treatment to control odours, allowing you to use it longer between washes without it developing a smell.
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For me, the silk liner provides comfort in a feather-light bundle that is easy to carry in any weather.
This versatile cotton liner from Lifeventure is perfect for general camping, hostel stays, and summer nights. It's durable, machine-washable, and even features odour control technology. Available in mummy or rectangular shapes with a built-in pillow sleeve, it's our Walks4all top choice for comfort and practicality.
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Lifeventure's 100% cotton liner stands out as a high-quality, affordable cotton option. Cotton liners are known for their soft, sheet-like feel, similar to sleeping in your bed at home, and this liner delivers on that cosy comfort. The cotton has a durable weave that can withstand frequent use and washing.
It's not the lightest or most compact fabric, but it remains fairly portable for camping. Many users choose cotton liners for warm-weather camping, hostel stays, or travel, as cotton is breathable and helps keep you cool in hot and humid conditions.
I've tested it a few times recently, and with the warm weather, it performed well on its own as a lightweight cover. It provides some warmth, but given the weather so far this year, I haven't had much chance to test it in cooler conditions.
It is available in both mummy and rectangular shapes, allowing you to match the liner to the shape of your sleeping bag. The mummy offers better thermal efficiency, while the rectangular provides more space to toss and turn. Lifeventure treats the fabric with Polygiene - a silver-ion treatment that prevents bacterial growth. This means the liner resists odours from sweat, enabling longer use without washing, which is ideal for multi-night backpacking trips or travel, as it keeps things fresher and more hygienic. When it does need cleaning, simply put it in the washing machine, as it is very easy to wash, and it dries faster than a full sleeping bag.
There is an integrated pillow sleeve at the top, which allows you to insert a pillow or clothes to create a pillow that won't slip off during the night. The liner's ripstop stuff sack closes with a roll-top and clip, much like a dry bag, making it easy to compress and also useful for hanging the liner to air out.
The disadvantages are the same for all cotton liners - they are heavier than silk or some synthetics, and they're not as warm when damp. Cotton loses insulation when wet, so it's not ideal for use in very damp, cold weather.
However, thanks to its versatility, comfort, and price, this liner is a favourite among outdoor enthusiasts for everything from camping trips to youth hostels. It is also listed on the DofE recommended kit list.
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When warmth is your priority, this heavyweight polyester fleece liner from Snugpack could be the answer. It essentially creates a cosy fleece sleeping bag inside your bag, adding extra insulation for winter camping or frosty nights. It is more suitable for car camping rather than backpacking, as it is bulky and not lightweight at 1 Kg.
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For extra cosiness in cold weather, the Snugpak Fleece Liner is a top choice. Its thick fleece material is incredibly soft, especially for those who dislike the nylon feel of some sleeping bags, and it offers a significant boost in warmth. In fact, Snugpak claims that this liner can instantly enhance your sleeping bag's rating by over a season, meaning a 2-season bag could perform like a 3-season, or a 3-season bag could get closer to winter conditions.
While I cannot attest to exact temperature gains, I found that it allowed my lightweight sleeping bag to be used on a couple of chilly nights in the Lakeland fells in March. You can use this on its own on mild nights, but on a hot summer's night, it will be too warm.
The design features a full-length zipper, which is excellent for easy access and venting. You can unzip it a little if you get too warm, or fully open the liner to use as a blanket. The hood features a drawstring to snug around your head for maximum heat retention, although in my opinion, it could be pulled tighter for a really snug fit.
Being made of fleece, it's naturally breathable and continues to insulate even when slightly damp, plus it dries very quickly - important for winter camping, where condensation can be an issue.
Weighing 1,000 grams, this item could be used for backpacking, but it's far heavier than the other tested items and quite large when packed down, and would not be suitable for most backpackers. For me, it is a good fit for a car camping kit, or if you don't have to carry it far on a short hike.
Being quite broad-shouldered, it also felt somewhat narrow for me, but most people should find it alright, as my shoulders are wider than most.
Overall, if you're looking for something warm to add to your sleeping bag for those cold nights car camping, or even in a caravan or motorhome, then this could be the liner for you.
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I've used a Cocoon silk mummy liner for many years without any issues, and this is the latest version of my one. The Cocoon Premium Silk Liner is a popular choice for campers, hikers, and travellers who want to enhance their sleep system without adding much weight. Made from 100% premium silk, it provides a soft, cool feeling against the skin while remaining breathable and moisture-wicking, making it suitable for both hot weather and mild-weather backpacking.
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The Cocoon Premium Silk MummyLiner is crafted from 100% premium silk. It provides a soft, cool sensation against the skin while remaining breathable and moisture-wicking, making it perfect for both hot climates and mild-weather backpacking.
The mummy shape provides a snug fit inside your sleeping bag, and the drawcord hood helps retain warmth around your head and shoulders for slightly cooler nights. Weighing just 135 g, it is among the lightest and most compact sleeping bag liners available, occupying very little space in your rucksack and making it ideal for ultralight trips or long-distance treks.
Silk is naturally hypoallergenic and odour-resistant, meaning you can use it for multiple nights without it developing a smell, and you'll still return with a sleeping bag that's clean inside. The build quality is impressive too, as double-stitched seams enhance durability and help this delicate-feeling liner withstand repeated use outdoors.
You can wash by hand or use a machine on a gentle cycle at a temperature of 30°C or lower. It should be washed separately and never with bleach or stain remover.
Overall, a fantastic silk liner that almost challenges the Silk Ultimate from Lifeventure for the top spot. If you're looking for a super-lightweight, high-quality silk liner that excels in comfort, packability, and breathability, the Cocoon Premium Silk MummyLiner is an excellent choice.
If you need a rectangular silk sleeping bag, Cocoon also produces a similar silk travel sheet with a side opening featuring a Velcro closure and a pocket for a pillow insert.
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As usual for my budget buy, I looked around on Amazon for a liner with many reviews and an average rating of over 4-stars, and this MYCARBON cotton sleeping bag liner fit that criterion with over 1,100 reviews at an average of 4.2. It's durable, soft, and roomy, making it the best budget cotton liner for keeping your sleeping bag clean or serving as a standalone sleep sheet on a warm night.
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The MYCARBON Travel Liner has become a popular choice on Amazon UK for its great value and comfort. Essentially, it's like taking a cotton bed sheet and sewing it into a sleeping bag liner shape - you get that familiar, cosy feeling of cotton against your skin, which many people prefer over slippery synthetics when travelling or camping in mild conditions.
The liner is quite spacious at 220 cm long and 90 cm wide, offering ample room to move during the night without twisting up. The top features an attached pillow pocket to keep your pillow in place.
There are the usual disadvantages of all cotton liners - they are heavier than silk or some synthetics, and they are not as warm when damp. Cotton loses insulation when wet, so it is not ideal for use in very damp, cold weather. One additional negative I found was that the press studs would come undone when turning over.
You can machine wash it at 30°C. Overall, it is a reliable, budget-friendly cotton liner that does its job. Note that for backpacking, it is heavier and doesn't pack down as much as the Lifeventure cotton liner reviewed above.
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As usual for my budget buy, I searched on Amazon for a liner with numerous reviews and over a 4-star rating, and this Trail fleece sleeping bag liner met that criterion with approximately 250 ratings at an average of 4.2. It provided comfort and warmth, making it the best budget fleece liner for keeping your sleeping bag clean for under £20.
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The Trail Outdoor Leisure Fleece Liner is a straightforward and effective way to add warmth to your sleeping setup without spending a lot. Made from lightweight microfleece, it offers an instantly cosy and warm feeling as soon as you slip inside.
I tested this on a few cool nights in early April and found it kept me warm enough when inside my lightweight sleeping bag. The fleece material is also quick-drying and machine washable, making it easy to maintain. It provides the dual purpose of keeping your sleeping bag clean and protected from wear, just like other liners.
Compared to the more expensive Sea to Summit Reactor, it wasn't as warm, it was heavier, and it did not pack down as small. Those differences and other features are really what the more expensive fleece liner offers.
Again, but probably due to my broad shoulders and frame, the liner did feel a little tight.
It's a mummy-shaped liner made of soft microfleece that helps keep you warm and cosy, although it comes with some minor compromises in fit and finish. For under £20, it's the best cheap thermal liner we've found.
To ensure you stay fully in the liner, once the zip is closed, there is a hook and loop fastening. If this isn't secured, running your skin over it isn't exactly comfortable. Either leaving it off entirely or choosing another fastening method would have improved this for me.
Overall, if you camp mainly in cooler seasons or find yourself just a bit cold in your current bag, the Trail fleece liner is a great value. It provides a comfortable layer of insulation and effectively adds extra warmth to your bag, similar to more costly Thermolite liners, though with added weight.
For car camping, scouts, festival camping, or short backpacking trips, it's a great, affordable insurance against cooler nights. For me, it's just a bit too heavy and bulky for longer hikes or backpacking and not warm enough for those freezing winter nights.
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Sleeping bag liners may be one of the most underrated accessories for sleeping bags and overnight camping, providing multiple benefits for campers and travellers. Here are some key advantages of using a liner, which combines comfort and warmth in a simple addition to your sleep system, of a sleeping mat, a sleeping bag and a sleeping bag liner.
Sleep system for backpacking or camping - A sleeping bag liner, a sleeping bag and a sleeping mat
Perhaps the main advantage of a sleeping bag liner is the extra warmth it offers. A liner functions like an additional blanket inside your sleeping bag, helping to trap your body heat and improve the bag's temperature rating. Depending on the liner's material, you can gain anywhere from about 2°C to 15°C of extra warmth inside your bag.
Thermolite Fleece
This makes liners popular among winter campers and backpackers who want to extend the use of a 3-season sleeping bag into colder weather, and for those who always feel the cold. By adding a warm liner, you can comfortably camp on colder nights without investing in a heavier, expensive winter sleeping bag.
A liner forms a barrier between you and your sleeping bag, protecting it from dirt, sweat, and body oils. After long hikes or warm nights, your body can carry grime and perspiration that would otherwise soak into your sleeping bag's interior. Over time, these oils and dirt can damage the insulation, especially in down sleeping bags, and lead to unpleasant odours.
Using a liner helps keep the sleeping bag clean and hygienic, as the liner catches most of the dirt. It's much easier to wash a liner than a full sleeping bag, so you won't need to launder your sleeping bag as often. This helps prolong the lifespan of your sleeping bag and maintain its performance.
Many campers discover that sleeping directly on a sleeping bag's interior, often made of nylon, can feel sticky or clammy. A liner adds a layer of soft, comfortable fabric against your skin, enhancing overall comfort. Liners are available in materials like cotton, silk, or fleece, which can be much gentler and cosier than the sleeping bag's shell fabric.
A silk or cotton liner can wick moisture and reduce clamminess, helping you sleep better. Even a thin liner can smooth the inside of a sleeping bag, eliminating the plasticky feel and making your sleep zone feel more like bed sheets. Essentially, a liner transforms your sleeping bag into a more luxurious, bed-like experience, which is especially pleasant after a tiring day of hiking.
A sleeping bag liner is a versatile piece of kit that can adapt to various situations. In hot weather or warm nights, your regular sleeping bag might be too much. That is when a liner alone can serve as an ultralight summer sleeping sack. Many campers use just a travel sheet (rectangular liner) on balmy nights or in tropical climates to stay comfortable without overheating.
Liners are also ideal for hostel stays or hut trips. When you're uncertain about the cleanliness of the provided bedding, a liner offers a personal clean sheet to sleep on. This is why rectangular sleeping bag liners (essentially lightweight sheets) are popular among backpackers and hostel guests, as they create a hygienic barrier in situations where the bedding might be questionable.
Additionally, in humid conditions, some liners, such as those made of moisture-wicking synthetics, can keep you drier and more comfortable by drawing sweat away from your skin.
By combining these benefits, sleeping bag liners truly deliver on the promise of comfort and warmth. They allow you to fine-tune your sleep setup for the conditions, all while keeping you snug and your sleeping bag protected. It's no wonder that many outdoor enthusiasts consider a liner to be an essential part of their camping gear.
Sleeping bag liners come in a variety of materials and styles, each providing different benefits in terms of warmth, weight, and comfort, which influence their price. Below, we outline the common categories of sleeping bag liners.
Cotton liners are an affordable and popular option, often recommended for first-time users. They feel like a soft bedsheet, are breathable, durable, and comfortable against the skin. A cotton liner provides a good protective layer to keep your sleeping bag clean, and it withstands frequent washing well.
On the downside, cotton is relatively heavy and bulky compared to other fabrics, making it less suitable for lightweight backpacking, where space and weight are at a premium. It doesn't pack down as small and offers only minimal warmth. Cotton liners are ideal for travellers in hostels or car campers where weight isn't an issue, or for warm-weather camping when you mainly need a hygienic sheet. On warm summer nights, you can use them on their own.
Silk liners are highly valued among backpackers for being extremely lightweight and compact. Silk is a natural fibre that is very light, often weighing less than 140g for a liner, and it compresses to a very small size. Despite its delicate feel, silk is surprisingly strong for its weight and can endure careful handling.
A silk sleeping bag liner feels soft and cool against the skin and is highly breathable, making it beneficial in both warm and cold climates. In cold weather, silk provides a modest layer of insulation, and in warm weather, it feels cool and wicks moisture, making it a versatile choice.
The hood on a silk mummy liner
Another advantage is that silk tends to trap less odour than cotton. On multi-day trips, a silk liner will feel cleaner and less smelly, which is excellent for odour control in your tent. The main drawback is the cost, as silk liners are usually more expensive. They also require more delicate handling, with some needing to be hand-washed only. If you're willing to invest, a silk liner offers one of the best warmth-to-weight ratios and comfort levels, making it ideal for ultralight backpacking trips where every gram counts.
If maximum warmth is your aim, fleece or other thermal synthetic liners are the warmest options available. Fleece liners are made from polyester fleece or microfleece material, effectively providing a substantial insulating layer inside your bag.
They can add significantly more warmth, often up to about 6°C to 14°C extra. This can transform a 2-season sleeping bag into a 3-season bag, or enhance a 3-season bag's performance in mild winter conditions.
The hood on a thermal sleeping bag liner
Fleece is also soft, cosy, and moisture-wicking, making it comfortable in cold and slightly damp conditions. However, fleece liners tend to be bulky and heavier. They can weigh anywhere upwards of 250g, depending on the model. Due to their bulk, they take up more space in your pack, so they're preferred by campers who are less concerned with ultralight gear or car campers. I know a couple of people who use them in their own beds on cold winter nights, just for that extra bit of warmth.
Some brands also offer insulated liners made from hollow-core fibres (e.g., Thermolite®), which are designed to maximise warmth while keeping weight moderate. These thermal liners can be a great way for winter campers to boost the warmth of their sleep system without buying a whole new down sleeping bag. Just be mindful, though, that the trade-off for a warm liner is often a larger pack size and extra weight in your backpack.
Aside from fleece (which is a type of polyester), there are other synthetic fabric liners that offer a balance of characteristics. Many lightweight liners are made from polyester blends or specialised fabrics like CoolMax® or microfibre. These are typically quick-drying, durable, and moisture-wicking, making them ideal for humid or wet conditions.
A polyester liner dries much faster than cotton if it gets wet or washed, and it can help wick moisture away from your body on sweaty nights. Synthetics often have a bit of stretch or give, which restless sleepers appreciate for freedom of movement. They offer moderate warmth, not as much as fleece, but more than silk or cotton. The price is usually in the mid-range.
One notable category is insulating synthetic liners (as mentioned above, such as those using Thermolite EcoMade fibres), which are designed to maximise warmth. For instance, a premium insulated polyester liner might claim to add around 14°C of warmth, using hollow-core recycled materials that trap heat.
The bottom opening of a Sea to Summit thermal sleeping bag liner with drawcord
Standard lightweight polyester liners don't provide much warmth but are excellent as all-weather travel sheets, especially in humid conditions where breathability and quick drying matter.
Another advantage: many synthetic liners are now made from recycled fibres (e.g., recycled polyester), so you can find eco-friendly options if sustainability matters to you. Overall, synthetic liners are a solid choice for versatile performance, being fairly lightweight, easy to wash, and good in variable climates.
Some liners are made from merino wool or wool blends. Merino wool liners are less common but offer excellent all-round performance: they provide a good warmth boost, wick moisture, and have natural antimicrobial properties, making them great for odour control. Wool liners tend to be expensive, similar to silk and not as widely available, but they are worth mentioning as a premium option for those who want the benefits of wool's temperature-regulating and odour-resistant qualities.
Along with the materials, liners come in different shapes to suit various sleeping bags and uses. The two main shapes are mummy-shaped liners and rectangular liners (also called travel sheets).
Mummy-shaped sleeping bag liners taper towards the feet and have a hood or drawstring at the top, similar to a mummy sleeping bag. These are designed to fit inside a mummy sleeping bag without bunching up.
Mummy liners are ideal for backpacking because they reduce excess material, which lowers weight, and they conform to the shape of mummy sleeping bags for better warmth. However, they can feel constricting for some, as there is less space to move or stretch.
Rectangular-shaped sleeping bag liners are simple in design, sometimes featuring a pillow pocket or opening, and provide a more spacious feel. They pair well with rectangular sleeping bags or can be used alone as a lightweight camping sheet. They often have a generous width, allowing for greater movement of legs and arms - a plus for those who dislike the tight fit of mummy bags.
Many rectangular designs can open like a blanket or unzip on one side, providing easy access in and out, which is especially useful in hostels or hotels where you might not trust the bedding. The trade-off is that rectangular liners tend to be a little heavier and less thermally efficient, since they have more air space for your body to warm up.
When selecting a liner shape, consider your sleeping bag style and comfort preferences. If you prioritise warmth-to-weight ratio and plan to nest it in a mummy bag, choose a mummy-shaped liner. If you desire versatility as a standalone sheet and more space, opt for a rectangular liner.
With a range of options available, from silk liners to fleece liners, mummy styles to travel sheets, each with different features, it is important to consider a few key factors to find the liner that best suits your needs. Here are the main criteria to remember when choosing the best sleeping bag liner.
The first step is to choose a liner that fits the shape of your sleeping bag for the best fit and performance. If you use a mummy-shaped sleeping bag (common in backpacking), a mummy liner will fit inside easily without bunching. Using a rectangular liner in a mummy bag can cause extra fabric to get tangled around you at night.
A silk mummy liner inside a sleeping bag, on top of a sleeping mat
Conversely, if you have a rectangular sleeping bag or plan to use the liner alone in hostels or huts, a rectangular liner (travel sheet) is the best choice. Also, pay attention to the dimensions, as liners often come in different lengths and widths. If you are particularly tall or broad-shouldered, look for a long or wide version so you have enough space. Some liners are marketed as having a 'generous width' or extra-long length for larger campers. Having a liner that's too tight can be uncomfortable and might tear under stress, while one that's too loose in a mummy bag is less thermally efficient.
Additionally, consider the entry and exit design since mummy liners usually have a top opening and may feature a partial side slit, while rectangular liners might open along one side or at the bottom. If easy access is important (for example, if you often get up at night or use it as standalone bedding), a rectangular design with a side-opening zipper or Velcro could be advantageous.
In summary, choose the shape and size that best suit your sleeping bag and body so the liner improves comfort rather than causes annoyance.
First, consider the conditions you'll be camping in and how much extra warmth you need. If you often camp in cold weather, a thermal fleece or insulated synthetic liner can provide a significant warmth boost. Some thermal liners can increase warmth by about 8-14°C. For moderate climates or as a versatile liner, silk or lightweight synthetics might be sufficient, offering a few extra degrees of comfort.
In hot weather or tropical travel, you'll want a liner that breathes well. Silk, lightweight cotton, or Coolmax-type synthetics are the best sleeping bag liners for this. Also, consider your personal sleeping 'temperature'. If you tend to sleep cold, err on the side of a warmer liner.
For backpacking trips or any journeys where you carry your own gear, every gram matters, so you need to balance warmth with weight. Materials such as silk and ultralight synthetics have a high warmth-to-weight ratio, making them ideal for weight-conscious travellers. A silk liner, for instance, can weigh as little as 100-150 grams but still offer comfort and some warmth.
Bulky fleece liners, although warm, can weigh over 500 grams and take up a lot of space, making them potentially unsuitable for long hikes where pack size matters.
Think about how the liner fits into your backpack. Many liners come with a stuff sack for storage, but not all pack down to an equally small size. Check the compressed size; a more compact liner will be easier to stow in your backpack. The stuff sacks are generally not waterproof, so you may want to pack your liner in its stuff sack inside a dry bag.
If you're an ultralight outdoor enthusiast, you might prioritise a very lightweight liner (such as silk or lightweight polyester) even if it offers slightly less warmth. Conversely, if you primarily car camp or only need to carry the liner over short distances, a heavier fleece liner could be acceptable for the additional cosiness it provides.
Since you'll be sleeping directly inside the liner, the feel of the material is a big part of the experience. Consider the fabric textures you find most comfortable.
Silk liners have a smooth, luxurious feel and won't cling to your clothes or skin. They're ideal if you tend to toss and turn because silk is slippery and moves with you. Cotton liners feel like a familiar bedsheet, offering a bit more friction, but they are cosy and not prone to static.
Fleece liners feel warm and fuzzy, almost like a lightweight blanket, which some love in cold conditions, although in hot weather, that same fuzziness might feel too warm. Polyester microfibre or Coolmax liners often have a soft T-shirt-like feel or slight stretch, which can be very comfortable and less clammy than plain nylon.
Also, consider whether you have sensitive skin or allergies. Natural fibres like silk and cotton are hypoallergenic for most people, whereas some cheap polyesters may have chemical finishes that cause irritation. Washing them first can often soften the fabric and remove some of these substances.
Breathability is another key aspect of comfort. Cotton and synthetics are generally breathable, but silk and specially engineered fabrics handle moisture better, reducing that sweaty feeling. Ultimately, the best sleeping bag liners are the ones you'll actually use each night, so choose a material you'll look forward to climbing into.
I usually have two sleeping bag liners in use - a fleece one for cooler weather and a silk one for warmer weather or hot nights on its own.
Another factor is how easily the liner can be cared for and maintained. Some sleeping bag liners are machine washable, often in cold water on a gentle cycle. However, materials like silk or wool may require more delicate care, possibly hand washing or using a special detergent, while cotton and polyester can usually cope with regular laundry detergent and machine drying (on low heat). Always check the label and manufacturer's washing instructions and follow them.
If you want something low-maintenance, check the washing instructions before purchasing. Polyester liners dry quickly and don't shrink, while cotton can shrink slightly and takes longer to dry. Silk should be air-dried to prevent damage.
On the wear side, cotton is quite durable but heavy; silk is lightweight but can snag easily on sharp objects. Some synthetic liners feature ripstop weaves or blends to improve their strength. If you'll be using the liner frequently or in tough conditions, durability might lead you to choose a sturdier fabric or at least carry a small repair kit, as rips can be sewn.
Also, check if the liner comes with a good-quality stuff sack for storage. Some liners should be rolled, not stuffed, into their sack to prevent damage. For instance, tightly cramming a cotton liner repeatedly can strain the seams or tear the carry bag, but rolling it neatly may extend its lifespan.
Price is also a key factor in choosing the best sleeping bag liners. Silk and high-tech insulated liners tend to cost more than basic cotton. Often, spending a little more on a quality liner that's comfortable, durable, and equipped with the features you need will pay off in the long term with better sleep and a longer lifespan.
While the above are factors to consider when selecting the right bag for your needs, some of the best sleeping bag liners have additional features that, if important to you, could influence your choice.
Some liners feature pillow pockets - essentially a sleeve for inserting a pillow or clothes used as a pillow, which helps to keep the pillow in place. I have noticed in the past that when my sleeping bag liner, sleeping bag, and pillow are all made from the same 'shiny' material, the pillow tends to slide off while I sleep. Having a pillow pocket prevents this by keeping the pillow securely in place during sleep.
Some liners are treated to help with odour control. For example, some Lifesystems liners are treated with Polygiene, which helps prevent the buildup of odour-causing bacteria, keeping your sleeping bag liner cleaner and smelling fresher for longer.
Some liners are treated with insect repellent, such as permethrin, or feature Insect Shield® technology. This might be beneficial for hikers and travellers in areas prone to mosquitoes or bedbugs, or if you are particularly susceptible to bites. However, over the years, I've spent hundreds of nights in tents and have not been troubled by mosquitoes in bed.
Some models feature zippers, drawcords, and Velcro to facilitate easy entry and exit from the liner. These also aid ventilation; if you're too hot, you can undo the zip or loosen the drawcord to allow more air in.
Press stud closure on a thermal sleeping bag liner
They might potentially create additional 'weak spots', but I haven't experienced any issues with zips breaking or drawcords snapping on the ones I've used.
The drawcord on a sleeping bag liner
If eco-friendliness matters to you, look for liners made from organic cotton or recycled fabrics. Some newer liners use 100% recycled polyester fibres.
By considering all these factors from material warmth to ease of washing, you can choose a sleeping bag liner that perfectly fits your camping style. What might be the best sleeping bag liner for someone else may not be ideal for you. The best sleeping bag liners are those that meet your warmth needs, feel comfortable to sleep in, and fit seamlessly into your gear setup.
Most of these are simply commonsense, but here are some tips on maximising comfort and lifespan of your sleeping bag liner:
Using a sleeping bag liner is a straightforward process. Open your sleeping bag and place the liner inside, aligning it with the shape of the bag. For a mummy liner, tuck the liner's hood or top edge into the hood of your sleeping bag, if it has one. Then, just climb inside the liner and into your sleeping bag, as you normally do. Ensure the liner is spread out smoothly to prevent lumps.
If you're using a rectangular liner as a standalone travel sheet, you can either crawl in like a sleeping bag or, if it unzips, get in that way.
On very cold nights, draw any hood or cinch cords on the liner to trap heat around your shoulders and neck. It may take a few nights to get used to the extra layer, but usually, liners move with you as you turn, becoming an integrated part of your sleep.
The arm openings near the top of a Sea to Summit Thermal Liner
A word of caution I've learned from personal experience over the years is to be careful when zipping up and unzipping your sleeping bag. You must ensure that you don't get the liner caught in the sleeping bag zip.
On hot or humid nights when a down sleeping bag or even a synthetic bag is too insulating, a liner alone can serve as a lightweight alternative to the sleeping bag, offering comfort and breathability. Many campers carry just a liner for summer camping, travel, or hostel stays. Because many liners are breathable, they allow airflow while still providing a snug feeling of being covered.
Rectangular liners that open up can serve as a regular top sheet on a bed, making them convenient for hostel bunk beds or situations where you need a clean layer under or over you.
When it's time to pack up camp, storing your liner properly will help it last longer. Most liners come with a small stuff sack; however, note that not all liners can simply be crammed in like a sleeping bag. Delicate materials such as silk and lightweight cotton should ideally be folded or rolled before placing them into the sack to avoid stressing the seams.
Size comparison between a Sea to Summit Extreme thermal liner, a Cocoon Silk liner and a 330 ml can
What I have found is that it is a good idea to air out your liner in the morning before packing it, especially if it's a bit damp from sweat. Usually, a few minutes draped over your tent or a camp chair will do, assuming the morning dew has dried. When you return home, ensure the liner is completely dry before storing it for long-term use.
You can store it in its stuff sack in your gear cupboard or fold it loosely if you have enough space. Unlike sleeping bags, liners aren't as susceptible to insulation damage, so compression isn't a major issue, except perhaps for fleece, which is bulky anyway.
One advantage of liners is their ease of cleaning, and washing your liner means your sleeping bag doesn't need to be washed as often.
Generally, I wash my liner after nearly every trip. Check and follow the manufacturer's instructions, but most fabric liners (cotton, polyester, fleece) are machine washable, and you can use a gentle cycle with mild detergent. Avoid bleach or fabric softeners, as these can damage fibres or leave residues.
For silk, wool, and certain technical liners, again, check and follow the manufacturer's washing instructions. Some silk liners can be machine washed on a delicate cool setting, but some can only be hand-washed in cool water with a silk-friendly soap.
I always wash my liner separately from items that could snag it. After washing, air drying is the safest for all materials, as it helps prevent shrinkage and preserves fabric strength. Silk and wool must be air dried (they'll dry quickly due to their thinness), while cotton or polyester can be tumble dried on low heat if the manufacturer's instructions permit.
Treat your sleeping bag liner with care, and it will last for years. My main silk liner is still going strong after nearly ten years. Avoid sitting on sharp sticks or rocks outside that could tear it. Keep it away from campfires where a stray spark might burn a hole, especially with synthetic or silk fabrics. The same advice applies to sleeping bags.
If your liner has a zipper, zip it gently to prevent snagging the delicate material. Over time, if the liner develops a small tear, you can repair it with a sewing kit or lightweight gear tape on the field, as you would a sleeping bag shell. Remember that a liner not only keeps you comfortable but also protects your sleeping bag, so by caring for your liner, you are indirectly ensuring your (more expensive) sleeping bag's longevity too. Whenever your sleeping bag needs a wash, use a liner afterwards to avoid washing the bag too often.
A sleeping bag liner may seem like a modest accessory, but it truly is the ultimate camping multitasker. It can add a layer of comfort, provide warmth, and serve as protection for your sleep system. By slipping a liner into your sleeping bag, you can sleep warmer on cold nights, stay cooler on hot nights, and keep your expensive sleeping bag much cleaner in the long run.
As you prepare for your next overnight adventure, consider packing a liner along with your sleeping bag, mat, and other hiking essentials. It weighs almost nothing but offers benefits on multiple fronts - extra warmth, hygiene, comfort, and flexibility.
Yes. Sleeping bag liners help keep your sleeping bag clean by trapping sweat and dirt, which reduces how often you need to wash the bag. They also provide extra warmth, usually between 2-15°C, depending on the material. Liners enhance comfort and can be used on their own in hot weather. Lightweight and adaptable, they are a smart addition to any sleep system.
It depends. Silk liners are ideal for lightweight travel and comfort. Fleece liners provide the most warmth, perfect for cold weather. Cotton liners are breathable and affordable, but they can be bulky. Choose based on whether you prioritise weight, warmth, or comfort and your budget.
You can use a sheet, blanket, or base layers as a sleeping bag liner. A bedsheet folded into a sack, a lightweight blanket, or wearing base layers can serve as a substitute in a pinch. These won't perform as well as a purpose-made liner, but will help keep your sleeping bag clean. For the best results, use a purpose-made liner with a tailored shape and fabric.
A liner can increase temperature by up to 15°C, depending on the liner type. Silk and cotton liners usually raise temperature by 1-3°C, while fleece or thermal liners can add up to 10-15°C under optimal conditions. The actual warmth depends on the liner's material, fit, and how well it is used inside the bag. Thermal liners are especially effective for boosting warmth in cold weather.
No, but it's highly recommended. A liner helps keep your (more expensive) sleeping bag clean, adds warmth, and improves comfort, and it can be used alone on warm nights. It's especially useful on longer trips, in changing weather conditions, or when staying in hostels. While not essential, many campers consider it an invaluable accessory for their sleeping bag.
No. Standard sleeping bag liners are not bed bug-proof and won't prevent bites. Bed bugs can crawl through gaps and bite through thin fabric. For protection, use permethrin-treated gear or bed bug-proof encasements. Some liners are treated to help deter bed bugs and mosquitoes. Liners are primarily for hygiene and a little extra warmth, not insect defence.
Wearing dry base layers helps retain body heat and keeps your sleeping bag cleaner. Clothes provide better insulation than sleeping naked. Avoid wearing bulky or damp clothing, as this can reduce warmth.
Silk for weight, fleece for warmth, cotton or silk for comfort. As we've outlined above, silk liners are ultra-light and breathable, ideal for travel. Fleece liners provide maximum insulation in cold weather. Cotton is soft and affordable, but it is bulkier and takes longer to dry.
Yes. Sleeping bag liners provide extra warmth, keep your sleeping bag clean, and boost comfort. They are particularly useful for increasing the longevity and hygiene of your sleeping bag. Lightweight and versatile, they are a proven upgrade to any sleep system.
Fleece liners are the warmest. Thick fleece or thermal synthetic liners (like Thermolite) can add up to 10-15°C of warmth. They're ideal for cold weather but bulky to pack. Silk or cotton liners provide minimal warmth by comparison.
Silk or cotton liners are usually the most comfortable, but it varies based on personal choice. Silk is smooth, breathable, and can feel cool or warm depending on the temperature. Cotton is cosy and familiar but heavier. Roomy or wide-cut liners also increase comfort for restless sleepers.
Yes. Liners improve warmth, protect your sleeping bag from dirt and sweat, and enhance comfort. They're lightweight, easy to clean, and versatile for different temperatures. Used correctly, they increase the effectiveness and lifespan of your sleep system.
July 2025
