Sleeping Bag

8 Best Sleeping Bag Liners For Added Warmth & Comfort

Pros
  • Insulated (works down to 25℉)
  • Mummy-shape fits in most sleeping bags
  • Soft & comfortable
  • Easy to get into
Cons
  • Not good for hot weather

My choice for the best overall sleeping bag liner is the Sea to Summit Reactor Thermolite. This fantastic liner is insulated, with a temperature rating down to about 25℉, and fits any mummy-style sleeping bag. On top of all that, it’s easy to get into and very comfortable.

The one downside to this popular liner is the insulation, which makes it a bit too stifling for hot summer nights. However, for the spring, autumn, and cooler summer months higher in the mountains, this is an excellent choice. If you’re more of a mountaineer, I recommend looking at the Sea-to-Summit Reactor Thermolite Extreme.

Sea to Summit Reactor Thermolite
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If sleeping bags are blankets, then the best sleeping bag liners are bed sheets. When it’s too hot, you can open a sleeping bag and just use a liner. When it gets too cold, you can add the liner to increase warmth. Without a liner, you’re more susceptible to sudden temperature changes, getting sick, and having a terrible night’s sleep.

Sleeping bags are great, and there are tons of options to choose from. However, liners can make them much more comfortable. They are designed to make you feel cozy and warm, helping to lull you into a peaceful slumber. Get a great night’s sleep in the outdoors with one of the best sleeping bag liners reviewed below.

My Review Process

I’ve been hiking and camping for nearly three decades. Throughout that time, I’ve experimented with different sleeping arrangements. I didn’t think I’d love sleeping bag liners, but they’ve become a great addition to my setup. With options to match a wide range of activities and temperatures, finding the best sleeping bag liner for you has never been easier.

When evaluating liners, I look at a few key components. First, the outer material, or what touches your skin, is an important consideration. I also look at how much warmth they add for colder nights and if they can be used by themselves for hot nights. Moisture-wicking ability, anti-odor treatment, packability, and durability are also considered.

With those things in mind, let’s dive into the best liners available today.

Best Overall Sleeping Bag Liner
Sea to Summit Reactor Thermolite
My Winner
Pros
  • Insulated (works down to 25℉)
  • Mummy-shape fits in most sleeping bags
  • Soft & comfortable
  • Easy to get into
Cons
  • Not good for hot weather

My choice for the best overall sleeping bag liner is the Sea to Summit Reactor Thermolite. This fantastic liner is insulated, with a temperature rating down to about 25℉, and fits any mummy-style sleeping bag. On top of all that, it’s easy to get into and very comfortable.

The one downside to this popular liner is the insulation, which makes it a bit too stifling for hot summer nights. However, for the spring, autumn, and cooler summer months higher in the mountains, this is an excellent choice. If you’re more of a mountaineer, I recommend looking at the Sea-to-Summit Reactor Thermolite Extreme.

Sea to Summit Reactor Thermolite
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Best Sleeping Bag Liner For Cold Weather
Litume Thermolite All Season Sleeping Bag Liner
My Winner
Pros
  • Warm & comfortable
  • Lightweight
  • Good breathability
  • Convenient drawstring
Cons
  • A bit bulky

When the temperature drops, reach for the Litume Thermolite Liner. My choice for best sleeping bag liner for cold weather, this synthetic option is both warm and comfortable. It’s also lightweight and offers good breathability in addition to the extra warmth provided.

The only downside is that the liner is a bit bulky. It may take a bit of creative packing to get everything stowed with the rest of your outdoor gear. However, if variable temperatures are forecast, I highly recommend taking this liner with you.

Make sure to check out our article on the best winter sleeping bags if you plan to do some cold weather outdoor adventures.

Litume Thermolite All Season Sleeping Bag Liner
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Best Sleeping Bag Liner For Warm Weather
Sea-to-Summit Coolmax Adaptor
My Winner
Pros
  • Keeps you cool in hot weather
  • Comfortable
  • Efficient moisture wicking
  • Ultralight
Cons
  • Not for cool weather

Summer camping is a blast, but if temperatures spike, getting comfortable before sleep can be challenging. The Sea to Summit Coolmax Adaptor is my pick for the best sleeping bag liner for warm weather. This sleeping liner is comfortable, has incredibly efficient moisture-wicking abilities, and weighs next to nothing (8.7 ounces).

You can use the liner in combination with a sleeping bag for added comfort. However, by itself this thin and ultralight liner doesn’t hold body heat well, so it’s not ideal for cooler temperatures. For hot summer nights, I recommend bringing this liner with you because of its moisture-wicking capabilities and enhanced breathability.

Sea-to-Summit Coolmax Adaptor
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Best Mummy Sleeping Bag Liner
Therm-a-Rest Synergy Sleeping Bag Liner
My Winner
Pros
  • Fits most mummy-style sleeping bags 
  • You can cinch the hood
  • Lightweight
  • Half-length zipper for easy access
Cons
  • No antimicrobial treatment

The Therm-a-Rest Synergy Sleeping Bag Liner is my choice for the best mummy-style sleeping bag liner. This highly versatile lightweight liner can fit inside dozens of the most popular backpacking sleeping bags and comes with an easy-to-cinch hood.

On longer hiking trips, the liner may start to smell bad. The polyester lining has great moisture-wicking capabilities, but smells can linger. Make sure to wash it regularly. Small negatives aside, with a nice mummy shape, ample comfort, and an easy access half-length zipper, I heartily recommend the Therm-a-Rest Synergy Sleeping Bag Liner.

Therm-a-Rest Synergy Sleeping Bag Liner
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Best Fleece Sleeping Bag Liner
Big Agnes Fleece Liner
My Winner
Pros
  • Comfortable
  • Durable
  • Warm
  • Lifetime warranty
Cons
  • Heavy

Fleece is a warm fabric, and the Big Agnes Fleece Liner was one of the warmest and comfiest liners I tested. Fleece is thicker than polyester or silk, which gives it more durability to keep up with the rigors of your outdoor pursuits. The Big Agnes Fleece Liner also comes with a phenomenal lifetime warranty.

Because the soft fleece is heavier than other materials, not everyone will opt for this liner. Ultralight enthusiasts may go for something thinner, and in the middle of the summer, the fleece can be a bit stifling. However, between the comfort, durability, and lifetime warranty, there are a lot of things to love about this liner.

Big Agnes Fleece Liner
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Best Silk Sleeping Bag Liner
Cocoon Silk Mummy Liner
My Winner
Pros
  • Extremely comfortable
  • Lightweight
  • Smooth against your skin
  • Cinch cord for the hooded portion
Cons
  • No side openings

Silk is an incredibly smooth fabric that feels wonderful on the skin. The Cocoon Silk Mummy Liner takes that incredible feeling and puts it in a liner. On top of the comfort, you can use this for warm nights as a standalone cover or to add a few degrees of warmth to your sleeping setup. This liner is also very lightweight and easy to bring on any camping trip.

Unlike other options, this liner only has a top opening instead of zippers on the side. It’s not a huge inconvenience, but it does make getting into the liner a little tougher. If you want maximum comfort and a silky smooth fabric to lull you into sleep, the Cocoon Silk Mummy Liner needs to be on your list of things to buy. I really love how it feels.

Cocoon Silk Mummy Liner
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Best Synthetic Sleeping Bag Liner
Nemo Tracer
My Winner
Pros
  • Great moisture-wicking capabilities
  • Antimicrobial finish (anti-odor)
  • Bluesign approval
  • Fits differently-shaped sleeping bags
Cons
  • Not as warm as others

The Nemo Tracer is my choice for the best synthetic sleeping bag liner. The liner has fantastic moisture-wicking capabilities along with an antimicrobial finish to reduce bad body odors. Additionally, the Tracer is bluesign-approved, meaning it was built to strict safety and environmental standards.

The Nemo Tracer is a great standalone liner or sleeping bag companion, but it isn’t as warm as some other options. It’s a great liner for summer weather and during the shoulder seasons when temperatures are still warm. And while you may not be bringing this liner out in the middle of the winter, it’s very versatile, fitting well inside both mummy bags and rectangular sleeping bags.

Nemo Tracer
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Alps Mountaineering Mummy Style Sleeping Bag Liner
My Winner
Pros
  • Durable
  • Small packed size
  • Easy to use and pair with sleeping bags
  • Inexpensive
Cons
  • A little heavier

The Alps Mountaineering Mummy Style Sleeping Bag Liner is my choice for the best value sleeping bag liner. This inexpensive and durable option is easy to use and pairs well with most sleeping bags. It also packs down really well for convenience on the go.

This option is a little on the heavier side (12.8 oz) but well within the normal range for sleeping bag liners. The material used is a cotton-polyester combination that works well but won’t be as comfortable as a silk liner. However, if you need a durable, long-lasting sleeping bag liner that’s easy to use and packs down well, this is a great choice.

Alps Mountaineering Mummy Style Sleeping Bag Liner
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Sleeping Bag Liner Guide

While all sleeping bag liners may seem the same, you don’t want to end up with one that feels uncomfortable against your skin, doesn’t add any warmth or takes up too much space in a backpacking pack. Before settling on your new favorite liner, take a look at my buying guide below to make sure your liner matches your outdoor ambitions.

Cost

Sleeping bag liners vary in price but generally cost between $20-100. You can find great budget options between $20-35. An average liner price hovers between $40-50, and high-end expensive liners are closer to $100.

Care

Many of the sleeping bag liners in this guide are machine washable. Having said that, it's important to read all care instructions to get the most out of your sleeping liner. Regular cleaning (hand washing or with a washing machine) is important to keep odors down and keep the liners soft to the touch.

Material Type 

The material your sleeping bag liner uses has a big effect on comfort and weight. The four main types of materials are:

  • Silk

Silk liners are the lightest options on the market and  help keep you cool in warm temperatures. They are not super effective at adding warmth, but the extra comfort can help even nervous outdoor sleepers find quality rest.

  • Cotton

Cotton liners tend to be one of the most affordable options. They provide good durability and adequate comfort but aren't as smooth or soft as silk. 

  • Fleece

Fleece options are some of the warmest but much bulkier than other materials.

  • Synthetic blends

Synthetic liners that use polyester or cotton blends offer superior breathability and moisture-wicking abilities but, again, lack the comfort of silk.

Comfort

Comfort is also related to material type, with silk taking the top spot for summer weather. However, extra comfort also comes from breathability, warmth (i.e., temperature rating), and anti-odor properties.

Based on these qualities, synthetic liners rise above the rest and can be used effectively for summer and shoulder season camping.

Shape

Since most sleeping bags have adopted the mummy style, many sleeping bag liners have a nice mummy shape to them.

However, there are also versatile rectangular models which fit inside non-mummy-shaped bags. If you already have a go-to sleeping bag, make sure your liner can fit snugly inside it.

Heat Rating

Sleeping bag liners can add a temperature boost of up to 25 degrees to your setup. It’s a little confusing because sleeping bags are often rated based on what temperature they work down to. So, if you have a 30-degree bag and add a 15-degree liner, you can feasibly camp down into the low 20s and be ok. Keep in mind that the degrees of warmth added varies with each liner.

Even silk options add a bit of warmth to your setup because you’re adding a layer. However, the amount added varies significantly. Silk tends to add between 1-5 degrees, while some fleece and synthetic material can add over 20 degrees.

Packed Size & Weight

Sleeping bag liners aren’t very heavy when compared to other backpacking items. However, the less weight you carry in, the happier you’re back will be. Most effective liners are somewhere between 6 and 15 ounces.

A liner that packs down into a small size makes it easier to stuff into a backpack. All the liners in this review pack down enough to stuff into a backpacking pack.

Summary

The best overall sleeping bag liner is the Sea-to-Summit Reactor Thermolite Liner. If you want the highest comfort level available, I’d recommend the Cocoon Silk Mummy Liner

For cold climates, opt for the Litume Thermolite All-Season Sleeping Bag Liner. And, of course, for value and budget shoppers, the Alps Mountaineering Mummy Style Sleeping Bag Liner is a smart choice.

Common questions

There are several points: added comfort, better breathability, a lighter covering for hot nights, and extra warmth under a sleeping bag for cold nights.

The best sleeping bag liner material is subjective, although silk options are the softest. However, the moisture-wicking and breathability properties of polyester and polyester blends elevate those options as well. Fleece liners tend to provide excellent warmth for colder backpacking trips.

No, you don’t have to use a sleeping bag with a liner, but the liner has several important benefits. Liners for backpacking are smaller and usually easier to clean than sleeping bags, so using one helps limit your post-trip laundry. You can also just opt for a liner if it's too hot or use it for extra warmth when it's cold.

Yes, you should put something under your sleeping bag. If you don’t, you’ll feel every rock, root, and uneven dirt mound beneath your tent. At a minimum, you should use a sleeping pad under your bag. Check out our best foam sleeping pads article for some excellent options. Some people may want to use a tent footprint as well for extra padding.

That’s a personal choice. With a sleeping bag liner, it’s easier to sleep without clothes on because of the added layer. However, if you run especially cold or just find it comfortable, you can sleep in a sleeping bag with clothes on.

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*The information on this site is based on research and first-hand experience but should not be treated as medical advice. Before beginning any new activity, we recommend consulting with a physician, nutritionist or other relevant professional healthcare provider.