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What Does A Sleeping Bag Liner Do? ( 2 important functions )

If you love camping and outdoors, chances are you already own a sleeping bag. This key piece of gear is one of the first things most people buy when they start venturing into outdoor recreation.

But few people own a sleeping bag liner.  They may not even know they exist or, if they’ve heard of them, might be unsure of their purpose.  If you’re wondering what exactly a sleeping bag liner does, we’ll cover some of the uses in this article.

So what do you need a sleeping bag liner for and what does it do.

The main thing sleeping bag liners are known to do is help keep the inside of your sleeping bag clean and dry. Liners effectively wick away sweat and this wicking helps keep you warm. Liners also keep the inside of you sleeping bag clean. The liner absords sweat and dirt and creates a barrier between you and your sleeping bag. You can then simply remove the liner and wash it.

Keeping Your Sleeping Bag Clean

One of the reasons campers purchase a sleeping bag liner is because it can play a big role in keeping your sleeping bag clean.  The reason this is so important is because a clean sleeping bag means it will last for a long time.

Having a clean bag also means you won’t have to do a lot of extra work once your camping trip is over.  Sleeping bags can be tricky to clean and may require professional cleaning if they get really dirty. So it’s in your best interest, to save both time and money, to keep your bag as clean as possible.  You will be able to go camping again sooner because your sleeping bag will simply need to be stored in between trips.

If you put a sleeping bag liner into the sleeping bag, it forms a barrier between you and the bag itself.  Then, if you sweat or have dirty clothes, the liner will get dirty instead of the inside of the bag. In addition to sweat and dirt, oils from skin and hair can also get onto the sleeping bag and build up over time.  Eating while inside the sleeping bag also can dirty the bag if you spill or drop food on it.

A sleeping bag liner is much easier to clean than the bag so it’s better to get the liner dirty instead.  Liners are also much cheaper than a sleeping bag, so if you have to purchase a new one, it will be much more affordable.

Even so, it’s a good idea to keep the sleeping bag liner clean too.  So make sure to wear clean clothes before getting inside the bag and liner.  Remove any sunscreen, bug spray, or other lotions and oils from your face to prevent them from rubbing off on the liner.

Do sleeping bag liners increase warmth?

Another reason some people choose to purchase a sleeping bag liner is because it can add warmth to the sleeping bag.  Sleeping bags are usually rated for specific temperature ranges that indicate how comfortable they will be.

Some people choose to buy a sleeping bag that is suitable for a mild climate because they do most of their camping in the spring and summer.  Still, there can be cool nights even during three-season camping. By purchasing a sleeping bag liner, you can add approximately 5 to 10 degrees of warmth to the sleeping bag.  This can make all the difference to your comfort when the weather turns a little bit cooler.

A sleeping bag liner will increase the usability of your sleeping bag and camp for more days in the year.  Having a liner on hand in case of unexpectedly cool weather may just save the camping trip and allow you to get a good night’s sleep.

Materials for Sleeping Bag Liners

There are a variety of materials which are used to make sleeping bag liners and they each have their advantages and disadvantages.

  • Cotton liners

Cotton liners give a lot of warmth and are quite comfortable against the skin because of their natural fibers.  But they can also be quite heavy and don’t pack down or compress well. A cotton sleeping bag liner is best for car camping but not at all ideal for backpacking.

  • Silk Liners

Liners made from silk are popular with professional hikers and backpackers.  It’s also ideal for those who want a light backpack because they don’t weigh very much. Silk backpack liners are not only lightweight and easy to pack in a backpack, but they are incredibly soft and smooth.  After you wash them, they are also fast to dry.

However, silk liners can be a little bit on the expensive side.  But if you need a lightweight backpack and a liner that is compressible, this makes up for the additional cost.

Silk is also quite absorbent and remains breathable in warm weather.


  • Fleece and Microfleece Liners

Another option is a fleece or microfleece liner.  They offer incredible warmth, usually up to 12 degrees, and will make the sleeping bag warmer in colder temperatures. Fleece dries quickly and will wick away moisture.  It’s also moderately priced, making it an affordable option compared to purchasing a winter sleeping bag.

However, fleece is also bulky and quite heavy so it’s not ideal for backpackers.  It can be used when car camping or if you want to camp in the backyard during cooler weather. Synthetic sleeping bag liners are an attractive option because they tend to be more durable than cotton.  They’re also lighter and slightly less bulky but can cost a little bit more.

  • Synthetic Liners

One of the drawbacks of a synthetic liner is that they absorb odors and may smell bad after being used several times.  However, they can’t be beaten for camping in damp conditions because they continue to insulate even when wet.


  • Insulated Liners

Insulated liners made from materials like Thermolite claim to add the most warmth, up to around 25 degrees.  They are usually made from hollow-core fiber insulation which dries much faster compared to cotton.

However, insulated liners can be expensive, depending on the type you purchase.

Sleeping Bag Liners Can Help Cold Sleepers

Even if you don’t plan to camp in colder temperatures, there is still a good reason to use a sleeping bag liner.  Some people tend to have a lower body temperature when they are sleeping and are referred to as cold sleepers.

Women, in particular, have been found to get colder at night compared to men.  This is why sleeping bags are designed for men and women.  They are also rated differently to take this temperature difference into account.

So even during the summer months, some people might want an additional layer of warmth at night.  Instead of purchasing an expensive down-filled sleeping bag, a liner is a good way to feel comfortable with minimal extra cost.

Sleeping bag liners come in many sizes as well.  Some are mummy shaped to fit easily inside that style of sleeping bag.  Others are rectangular and ideal for more traditional bag shapes. To get the most warmth from adding a liner, opt for one that resembles the shape of your sleeping bag.  This will eliminate extra space where air could get trapped and chill you during the night.

Getting Into a Sleeping Bag with a Liner

One of the drawbacks some people mention when it comes to using a liner is that they can be difficult to get into.  There is nothing connecting the liner to the sleeping bag, so it can get bunched up or twisted inside the bag.

You may also have to wiggle or twist a little bit to get inside.  Some liners hug tighter to the body so there’s no extra space for heat to escape.  Others are a little looser for those who like to move around while they sleep.

If the liner you purchased as a drawcord, you can cinch it to help keep heat inside before zipping the sleeping bag up.  One tip is to get into the liner first, and then climb into the sleeping bag so everything is smooth and comfortable.

Sleeping Bag Liners are Versatile

Another benefit to using a sleeping bag liner is that it can be used for so much more than just keeping your warm and your bag clean.  Instead, you can use it on its own like a sleeping bag for hotter weather.

Adding a sleeping bag liner to your backpack as one of the 10 essentials is also a way to add minimal weight but still have something in case you unexpectedly need to spend the night outside.

If you don’t want to sleep inside the liner, just lie it on top of your body like you would a sheet in your bed at home.  It can also be bunched up and used as a pillow when you don’t need to use it for warmth.

Downsides of Sleeping Bag Liners

Some people find that sleeping bag liners are difficult to get into because they do not attach to the inside of the sleeping bag.  The section detailing tips on how to get into a sleeping bag liner does offer some tips on how to make this process easier.

Another drawback is that they do add extra weight to your backpack.  For backpackers, this can be a major problem because pack weight is key to their success. However, if your sleeping bag is lightweight and rated for the right temperature, you shouldn’t need a sleeping bag liner too.  Packing a liner in such a situation would add some unnecessary weight.

Other than these two things, sleeping bag liners are almost always a good idea to have on hand.  If weight is not a concern when packing for your camping trip, it can’t hurt to add a liner to your supplies.

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Rickie Arms

Hi, I'm Rickie Arms, owner of Glampingorcamping.com. I am so invested in writing the best and most informative articles for you that I went out and bought a travel trailer just so I could write about it for you. I spend just about all of my off time both camping and glamping so I can share everything I have learned and will learn with you. I have spent my whole life camping and over the last 10 years, I have spent a large amount of time checking out glamping experiences with my wife and kids as well. Thank you for coming by and we hope to see you back here getting great information in the future. Rick Arms-

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