Sleeping Bag Liners – Why You Should Use One

All you need to know about what sleeping bag liners are, the benefits of using them, and the different types available


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Alan is our resident expert on all things wild camping. He loves nothing better than to get out of the house with just his ex-Army sleeping gear and a stove, and head off to the remotest spot he can find near his home on the south coast of the UK.
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So a friend told you to use a sleeping bag liner, but you're not convinced about why you should use one with your backpacking sleeping bag

Maybe you think your sleeping bag is just enough, and you don't need anything that will add weight or take up additional space in your backpack.

It doesn't matter whether you have the coziest or warmest sleeping bag. A sleeping bag liner is a must-have for any camping trip to keep your sleeping bag clean, add warmth, and enhance your sleeping bag's longevity and performance.

In this article, you'll learn what a sleeping bag liner is, its types, materials, why you should use it, how to use it and how it can help you enjoy cozier camps and improve your sleeping bag's long-term performance.

Let's dive in.

sleeping bag liner guide

What Is a Sleeping Bag Liner?

Sleeping bag liners are a type of insert, usually lightweight cloth sacks that are inserted into a sleeping bag to add extra comfort, insulation, and to prevent dirt from reaching your sleeping bag to keep it clean. They're different to bivvy bags, although newbies sometimes get confused by the terminology!

As a camper and an outdoor enthusiast, you will attract dirt into your sleeping bag, which will make it dirty, invite bed bugs and affect the lifespan and performance of your sleeping bag.

A sleeping bag liner can protect you and protect your sleeping bag, just like how bed sheets do on your bed.

Meraklon Thermal Sleeping Bag Liner Navy

Meraklon Thermal Sleeping Bag Liner Navy. (Image credit: Sub Zero Technology Ltd on Flickr CC BY 2.0)

Types of Sleeping Bag Liners

Different sleeping bag liners are available, each specific usage and made for various conditions. Below are some of the most popular options available:

Travel Sleeping Bag Liners

These sleeping bag liners are specifically for use when travelling. 

Travel sleeping bag liners are designed specifically for those who travel and stay in hotels or places with questionable cleanliness standards.

They are more popular among hut-to-hut travelers (hikers, skiers, etc.) who don't want to sleep directly on a bed that many individuals have slept in before. 

Most travel sleeping bag liners are made from silk or cotton and are designed to be small protective sheets that separate you from the sheets and mattresses in your hostel.

Cold Weather Sleeping Bag Liners

Cold weather sleeping bag liners add extra warmth to your sleeping bag during extreme weather conditions.

These sleeping bag liners are generally made from fleece, Thermolite, or Primaloft insulations to help trap extra heat and keep you warm at night.

Cold weather sleeping bag liners are generally sold with a temperature rating to help you know how much extra warmth they will add to your sleeping bag.

If you're going to use a cold-weather sleeping bag liner, you should opt for one with a temperature rating that'll best suit your condition. For example, if your sleeping bag has a temperature rating of, let's say, 30 degrees Fahrenheit, and you want to make it 50 degrees, you should get a liner with a temperature rating of 20 degrees Fahrenheit.

Warm Weather Sleeping Bag Liners

Warm weather sleeping bag liners are ideal for use in hot weather conditions. They mostly have cotton, silk, or merino wool materials which have moisture-wicking capabilities to wick moisture away from your body to help keep you cool.

These sleeping bag liners offer minimal insulation, ensuring they don't add extra warmth, making them perfect for summer camping.

Sleeping Bag Liner Shapes

Sleeping Bag Liner Shapes

Like sleeping bags come in different shapes, sleeping bag liners also come in various forms to ensure they fit perfectly in your sleeping bag. Below are some of the popular sleeping bag liner shapes:

Mummy Shape Sleeping Bag Liners

Mummy-shaped sleeping bag liners use a tapered shape precisely to fit mummy sleeping bags. They are tapered towards the bottom to provide a closer fit and a little less roomy than regular sleeping bag liners but mainly offer more warmth.

These sleeping bag liners are usually more lightweight and packable than regular-shaped sleeping bag liners.

Rectangular Shaped Sleeping Bag Liners

Just like how mummy-shaped sleeping bag liners have a shape that makes them fit in mummy sleeping bags, rectangular-shaped sleeping bag liners fit in rectangular-shaped sleeping bags.

However, they usually don't insulate as well as their mummy-shaped counterparts but are often more spacious and ideal for standalone use in summer.

Regular Sleeping Bag Liners

These are standard sleeping bag liners designed for use in any sleeping bag or on hostel beds. 

Regular sleeping bag liners are great for use as a standalone liner or add an extra layer of comfort and protection when staying in hostels while traveling.

Double Sleeping Bag Liners

Double sleeping bag liners have shapes that make them perfectly fit double-shaped sleeping bags to accommodate two adult sleepers. This sleeping bag liner is great for couples who travel together and use a double sleeping bag.

Long Sleeping Bag Liners

These can be regular, mummy-shaped, rectangular-shaped, or double sleeping bag liners. They are longer with an extra length to accommodate taller sleepers. 

What Are Sleeping Bag Liners Made Of?

Nowadays, sleeping bag liners come in many different materials, each with advantages and disadvantages. 

The liner material you should choose will depend on how you plan to use the sleeping bag liner. Some of the most popular materials are:


Thermolite is a type of synthetic insulation that is lightweight and engineered from Polyester fibers. It offers superior warmth, and you can use it as a substitute for natural insulators due to its durability and varying forms produced in

Thermolite works by trapping warm air within the material to keep you warm even if wet. Thermolite sleeping bag liners work by wicking sweat away from your body and dry 20% faster than other insulating fabrics and 50% faster than cotton.


Primaloft is one of the leading insulation brands, usually found in synthetic jackets and sleeping bags.

Primaloft sleeping bag liners use unique technology to trap the heat leaving your body into a collection of air pockets and offer a better warmth to weight ratio, ideal for cold nights camping.

Some of the benefits of sleeping bag liners made from Primaloft materials include lightweight, breathability, pill-resistant, fast-drying, easy-care, and durability.

Attaching PrimaLOFT To Fleece Lining

Attaching PrimaLOFT One To Fleece Lining. (Image credit: kelly on Flickr CC BY-SA 2.0)


Fleece is mainly found in cold weather sleeping bag liners due to its insulation value. They gave a plush fabric to help keep you warm and cozy in cold weather conditions.

While it's often affordable material, fleece sleeping bag liners are generally heavy and bulky compared to other sleeping bag liner materials.


Cotton is one of the most popular sleeping bag liner materials. It's more cost-effective and wicks moisture away from your body to keep you cool on warm nights.

Sleeping bag liners made from cotton are great for summer camping. However, they are pretty heavy and bulky, which may deter some campers/backpackers from buying.


Sleeping bag liners made from silk are great for camping in hot or humid conditions. Silk is incredibly lightweight, comfortable against the skin, and works by wicking sweat from your body to keep you cool in hot weather conditions, making it ideal for frequent use and a great alternative to cotton.

However, silk is one of the most expensive materials around, and sleeping bag liners made with silk materials generally have a high price tag.


Wool-based sleeping bag liners are excellent insulators and wicks away sweat from your body to keep you warm. However, it's also expensive, though not as expensive as silk, and is slightly heavier and bulkier than silk liners.

Why Should You Use a Sleeping Bag Liner?

Now that you have a great understanding of sleeping bag liners, their types, shapes, and materials, let's go over their purpose and why it's a must-have piece to add to your sleeping bag. 

Why Should You Use a Sleeping Bag Liner

Adds Warmth to Your Sleeping Bag

Sleeping bag liners can add extra warmth to your sleeping bag, ideal for camping in cold weather conditions. 

They have materials that can trap heat and wick moisture and sweat away from your body to keep you warm and cozy.

Some sleeping bag liners, such as cold weather sleeping bag liners, come with a temperature rating which can help you choose one based on the amount of warmth you want to add to your sleeping bag.

Keeps Your Sleeping Bag Clean

Sleeping bag liners add a barrier between you and your sleeping bag, which can help prevent sweat, moisture, body oils, and dirt from reaching your sleeping bag to keep it clean and prevent foul odor.

As you use your sleeping bag more often, dirt and sweat will accumulate over time which is not something you want in your sleeping bag.

Increases the Lifespan of Your Sleeping Bag

Not using a sleeping bag liner in your sleeping bag will not only make it dirty but will also increase the frequency at which you wash your sleeping bag.

Frequently washing your sleeping bag will affect the bag's quality insulation, make it prone to tear, and ultimately reduce the lifespan of the sleeping bag. A sleeping bag liner can help prevent frequent washing, which will help ensure that the bag lasts longer and retains its insulation. Sleeping bags can be quite costly - anything that maximises its useable lifespan has to be a bonus!

Can Be Used as a Standalone Sheet

Apart from use in a sleeping bag, you can use your sleeping bag liner as a standalone sheet in various places and situations.

Protects You Against Insect Bites

The last thing you will need when comfortably sleeping in your sleeping bag is an insect bite, especially if you're camping where there are insects. A sleeping bag liner can add a layer of protection against insects and other bed bugs so that you stay safe and have a night of uninterrupted sleep.

Protects You Against Contaminated Sheets

If you are a hut-to-hut traveler and often spend your night in hostels, you'll be sleeping on sheets and mattresses used by other people, and there's no guarantee that those sheets are not contaminated.

Using a sleeping bag liner can help protect you against those contaminated sheets, keep you safe, and ensure that you sleep comfortably with absolute peace of mind.

Easy to Wash and Dry Quickly

Sleeping bag liners are very easy to wash and dry quicker, which is great since you might be washing them frequently, and it doesn't take a lot of time and effort.

They’re Lightweight and Packable

Most sleeping bag liners are very lightweight and don't add any noticeable weight to your backpack. They are also easily packable, and you can pack them in no time, so you don't have to worry about packing them into your bag.

How to Use Sleeping Bag Liner

Using a sleeping bag liner is very straightforward and requires no technical know-how.

Follow the following steps to use your sleeping bag liner:

  • Remove the liner from its sack

  • Straighten it up

  • Then unzip your sleeping bag and put the liner inside while ensuring that the opening stays at the head section of the sleeping bag

  • Now you need to slide yourself inside by putting your legs first and then pushing your whole body inside until it completely covers your entire body

  • Now you need to zip up your sleeping bag, and you're good to go

Frequently Asked Questions

How Does a Sleeping Bag Liner Work?

A sleeping bag liner works by trapping heat, wicking sweat and moisture away from your body, and adding an extra layer between you and your sleeping bag to keep you warm, comfortable, safe and protect your sleeping bag from dirt, sweat, and body oils. 

Can You Just Use a Sleeping Bag Liner?

It depends on the environment, materials, and thickness of the sleeping bag liner. If the liner is thick enough and has quality materials, and the ground is not wet, you can consider using just a sleeping bag liner. However, if the ground is wet, then it's not a good idea to use just a sleeping bag liner because they are not waterproof enough to keep you dry and comfortable in such situations 

How Much Extra Warmth Does a Sleeping Bag Liner Add?

The amount of extra warmth a sleeping bag liner adds will depend on its materials and temperature rating (for cold weather sleeping bag liners). Sleeping bag liners made with Fleece, Thermolite, and Primaloft fabrics generally warm your sleeping bag.

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