Best Merino Wool Sleeping Bag Liners 2024

Last Updated on 08/03/2024

best merino wool sleeping bag liners

Who Makes the Best Merino Wool Sleeping Bag Liners?

In this guide to the best merino wool sleeping bag liners, you will learn why there are only two companies outside of New Zealand that make them and who those brands are. Because there are so few options available in the USA, making your decision should be easy and will largely be determined by your budget.

When we are out camping, a good night’s sleep is a welcome reward after a day full of activities and will set you up for a great next day too. A merino wool sleeping bag liner will take your sleeping experience to the next level of comfort, creating extra warmth, extra coziness, reducing odors, and soft and comfortable. So read on and discover more about the benefits of merino sheep’s wool and how a sleeping bag liner can benefit you.

Camping and sleeping outdoors can often be a mixed bag. Even in summer, it can turn cold on us, especially if we are in an exposed location. As such, you want to ensure you have a comfortable and reliable sleeping system. Not only does it feel fantastic to crawl into a warm and dry sleeping bag at the end of the day, it feels just as good waking up in one.

An easy way to get more out of your sleeping bag is to use an additional sleeping bag liner made out of merino wool. A sleeping bag liner in itself helps with additional warmth by adding an extra layer of insulation along with creating a hygiene barrier between you and your sleeping bag, which isn’t as easy to wash as a liner.

The added merino wool to a sleeping bag liner not only increases its ability to keep you warm but also has the ability to wick water away from your skin or clothes. This guide will explore the benefits of merino wool sleeping bag liners and the only two options out there.

The 2 Best Merino Wool Sleeping Bag Liners

Big Agnes Merino Wool Sleeping Bag Liner

Big Agnes Wool Sleeping Bag Liner, Gray, 82"

  • WEIGHT: 1lb / 454g
  • MATERIAL: 87% New Zealand Merino Wool, 13% Nylon

The Big Agnes Merino Wool Sleeping Bag Liner maintains excellent cooling and heating properties depending on the season. This is because merino wool has the ability to adjust to your body’s needs in different temperatures and environments. The material is blended with nylon for added durability so that you can stretch the fabric and wriggle around without damaging it.

The Big Agnes is a sleeping bag liner made from merino wool that can be used as a standalone thin sleeping bag or placed inside your thicker bag for added comfort. The liner itself will add an extra 5-10 degrees Celsius, or warmth in colder climates, but it can also reduce the heat in summer by wicking moisture away from your skin.

This merino wool sleeping bag liner features a long side opening that allows easy access and ventilation, along with being fully reversible, so you can keep this opening on the same side as your sleeping bag zip from the start. The seams and stitching of this sleeping bag liner are smooth and comfortable, and there is a small hood at the top to cover your head if need be. There are also hooks at both the top and the bottom for easy long-term attachments to your sleeping bag.

VERDICT: The Merino Wool Sleeping Bag Liner from Big Agnes is the perfect way to increase your comfort and warmth inside your sleeping bag. The extra insulation, combined with the cooling properties in the heat, make this sleeping bag liner a must-have for all-year camping. The wool itself doesn’t scratch the skin, and the wide opening, attachment hook, and small hood all add extra usability to this sleeping bag liner. At the end of the day, you will sleep much better with this than without it.

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Cocoon Merino Wool Mummy Liner

Cocoon Merino Wool Mummy Liner

The Cocoon Merino Wool Mummy Liner is another excellent sleeping bag liner made from Merino wool that will ensure your night’s sleep is as comfortable as it can be, especially in winter. This is a simple sleeping bag liner that can be used by itself or in conjunction with a sleeping bag that will add the benefits of merino wool to your sleeping experience.

The Cocoon Mummy Liner is 50% cheaper than the Big Agnes, and that’s because it is missing some of the features of the Big Agnes, such as having a wide side opening or having foot and head attachment hooks to keep it in place inside your sleeping bag. What it does have is a drawstring at the top, which allows you to fully cocoon yourself inside, creating even extra warmth in colder climates.

It’s also very comfortable as the wool fibers used are extra fine, creating a super soft layer on your skin without any scratchiness at all. Couple that with this product being very lightweight and not too expensive, and it’s easy to see how a merino wool liner like the Cocoon Mummy should be included on every camping trip.

VERDICT: The Cocoon Merino Wool Mummy Liner is a very easy-to-use sleeping bag liner that provides all the benefits of merino wool in a lightweight and comfortable way. It fits neatly into almost any sleeping bag, and while not quite as functional as the Big Agnes, for its price point, the Cocoon Mummy Liner is an excellent buy for an excellent night’s sleep.


guide to merino wool sleeping bag liners

Benefits of Merino Wool Sleeping Bag Liners

Merino wool comes from sheep primarily raised in Australia and New Zealand, but can also be found in lesser quantities around the world. The fleece of a merino sheep is processed into wool after shearing, cleaning, carding, and spinning it into long threads.

Merino wool is used primarily for clothing, but it’s also used for a range of other products like blankets or mattress insulation due to its unique properties. Sleeping bag liners made from merino wool are clearly something very useful too.

We have a full rundown of the benefits of merino wool here (link to your page), but to provide a shorter summary, merino wool has the following benefits:


The merino sheep tend to favor colder climates, and they are able to survive easily due to the thick and incredibly warm wool they grow on their bodies. It’s very thick and has lots of small areas for air to become stuck and maintain an even temperature – which in turn will keep you warm too when you need it.


This is one of the wonders of natural fibers; sometimes, they can produce results that manmade ones just cannot replicate – merino wool is able to thermoregulate itself, which means when you are cold, it will warm you up, but when you are hot – it will cool you down.

The process itself is called the ‘heat of sorption‘ and is based on the moisture content of the wool and your body. If you become hot and start to sweat, the wool will absorb the moisture, drawing it away from your skin and making you feel cooler. The opposite happens when it’s cold, the wool will release moisture, and this will help warm your skin up. So no matter if it’s a sunny day or a snowy night, merino wool has you covered to keep you comfortable.


In addition to the moisture absorption properties, merino wool is also great at taking moisture away from your skin and allowing it to evaporate outside. This means you can get into a merino wool sleeping bag liner wet and wake up dry (or dryer). This also works if you are wearing a merino wool jumper and start to sweat – the wool will pull the moisture away from you.

Odor and Static Resistant

The moisture-wicking properties of merino wool are also great at taking bad odors and locking them away, keeping you smelling (and feeling) cleaner and better after a few days without a shower. Likewise, this ability neutralizes static electricity so you won’t accidentally shock your partner when you lean in for a hug.

Comfort and Durability

Merino wool is very soft, very stretchy, and lightweight but also very durable, so it will last you years. It’s also hypo-allergic, fire-resistant, and protects against UV rays, making it an outstanding fabric for making and wearing clothes to last, even if the fashion of colors changes over time, and it is perfect for camping and outdoor lifestyles.

Sustainable Sources

Unlike artificial fabric, merino wool is natural and comes from sheep, so provided there is land for them to graze, the fabric itself becomes a renewable resource. In our world of ever-increasing populations – renewables are the future.

Big Agnes Wool Sleeping Bag Liner, Gray, 82"

Guide to Merino Wool Sleeping Bag Liners

While Merino wool is used in many types of clothing, its foray into other areas hasn’t been great and this is mainly due to price as synthetic materials, while inferior – can be made much cheaper. As such, there are only two sleeping bag liners to choose from, as we reviewed above, so we will compare them head to head on a few important aspects.

Wool Blend

The higher the merino percentage, the better you are able to enjoy its properties, and when we compare the two: the Big Agnes is made from 87% merino wool with 13% Polyester, while the Cocoon is 100% Merino wool. The addition of synthetic fibers like nylon help to increase the durability and longevity of the wool and is generally not considered a bad thing.

Warmth Rating

The Cocoon Mummy, sleeping bag liner, will add up to 7 degrees C (12 F) of extra warmth to your sleeping bag, while the Big Agnes is slightly less by adding 5-6 degrees C extra warmth to your sleeping bag, this is a small margin, but one to consider nevertheless. Warmth ratings are often provided by the manufacturer and provide an insight into how warm the liner will be. Merino wool is possibly the warmest type of sleeping bag liner however, Sea to Summit uses something called Thermolite, which is also very warm.

Weight and Packing Size

Both merino wool sleeping bag liners come with a small stuff sack to you can stow them away quickly when not in use. Both are also evenly weighted, coming in at just over half a kilo (.500g / 1 lb) so won’t weigh you down while hiking. Weight and pack size are important if you are backpacking or hiking with a limited capacity. Merino wool offers an excellent warmth-to-weight ratio and is considered to be very lightweight.

Size and Shape

Both of these sleeping bag liners made from merino wool are very similar shapes as they are both designed primarily to go inside a sleeping bag which is generally narrower at the feet than they are at the shoulders. That being said – the Big Agnes is almost double the width at the shoulders at 152 cm (60 inches) across while the Cocoon Mummy is 80 cm (32 inches) at the shoulder, making it more suitable for larger people.

The size and shape of the sleeping bag liner should match your sleeping bag and also your body type. So if you are over 6 feet tall and have a mummy sleeping bag you should be looking for a large mummy sleeping bag liner.

Hood and Drawcords

The two products take a slightly different approach here with the Big Agnes having a small and compact hood for you to pull in over your head for increased warmth, while the Cocoon Mummy utilizes a drawcord (or drawstring) to synch the top together to achieve the same result. The extra materials of the Big Agnes will end up giving you a more comfortable night’s sleep than having a drawstring pulled tight around your head.

Hoods really do help to keep your head warm when you sleep and then also act as a comforter to whatever you are using as a pillow. If you are using a liner to help keep your sleeping bag clean then having a hood on your liner will help to protect it from your face and hair which can get dirty when camping. Being able to sinch the hood in prevents it from ‘traveling’ during the night and traps in the warmth.


Neither of these sleeping bag liners is overly cheap, as merino wool is more expensive than most synthetics which drives the prices up. The Big Agnes is approx. 50% more expensive, however for the cost you get a wider bag with a hood and attachments to keep it in place, while the Cocoon Mummy is more simplistic in its design.

Sea to Summit Thermlite Reactor Fleece Sleeping Bag Liner

Are Merino Wool Sleeping Bag Liners the Warmest?

Merino Wool is very good at creating insulation and keeping you warm, but is it the warmest out there? Well, the answer is not very straightforward. Overall, merino wool is one of the warmest materials you can use. However, the cost of production has tempered its use. It’s also hard to pin down a number as merino wool moves moisture around far better than synthetics which means humidity comes into play in the equation.

Merino wool is best used in damper or more humid conditions as it deals with water vapor or droplets far better than the competition. If used in conjunction with a Gore-Tex sleeping bag or outer shell and you will be able to go to bed wet and wake up dry, which is a hard ask for any other materials.

Why Are There Only Two Merino Wool Sleeping Bag Liners?

The reason there are so few sleeping bag liners made from merino wool is that it is so expensive to use. As we have mentioned above, the cost of merino wool in comparison to synthetics is why it’s not more widely used. For comparison, a Big Agnes cotton sleeping bag liner is almost 200% cheaper than the Merino Wool version. This has limited the market to people who can afford the extra cost or those dedicated enough to their camping comfort to spring the extra cash. Much cheaper synthetics tend to rule this product range as a result.

Do Merino Wool Sleeping Bag Liners Add Much Warmth?

Merino wool sleeping bag liners add warmth to any sleeping bag by trapping warm air in their insulative fibers. Both the merino wool sleeping bag liners in this guide – the Big Agnes and the Cocoon Mummy add 6-7 degrees C (12F) of warmth to your body. Coupled with some merino base layers you can add even more warmth to your existing sleeping bag (no need to buy a new one).

Can You Use a Merino Wool Liner as A Sleeping Bag?

You can use a merino wool liner as a sleeping bag if it is warm enough, but that comes with some considerations. Sleeping bags are often designed with an outer shell layer that will allow you to sleep outdoors and still stay dry (unless it rains heavily), while sleeping bag liners are designed to be inside a sleeping bag.

In summer, inside a tent then, they will work quite well, but in winter – the drop in temperatures at night would not make a merino wool sleeping bag liner a suitable sleeping bag replacement.


A sleeping bag liner adds extra warmth to your sleeping bag, along with helping keep your sleeping bag cleaner for longer. Adding one of the best merino wool sleeping bag liners not only gives you the added warmth and hygiene of a liner but also gives you the additional odor and water wicking properties along with the long list of benefits of merino wool. While not on the cheap side of things, for avid hikers and campers the extra cost may be well worth it.



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This article has been written and/or edited by Andrew N. 20+ years of hiking, mountaineering, and camping experience, with access to all the latest outdoor gear.

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