What is a Sleeping Bag Liner? Do You Need One?

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One of the most unsung heroes of all camping gear, perhaps you’ve heard of sleeping bag liners before and thought they were unnecessary. After all, they’re nothing more than a thin sack of fabric, often sold at a higher price than you’d expect. Right?

That’s what I thought at first as well, but now that I have my own liner, I regret not changing my opinion sooner. So what are these little sacks? And do you actually need one?

What is a Sleeping Bag Liner?


What is a sleeping bag liner, you ask? Well, it’s exactly what it sounds like – a liner for your sleeping bag. In essence, you can think of it as bed sheets for your sleeping bag, offering you added warmth and comfort, especially on chilly nights.

However, the function of a sleeping bag liner extends well past its ability to provide a little extra warmth. We’ll get into these benefits later in the article, but first, let’s just briefly cover the different types of liners that you can choose from.

Styles of Bag Liners

When it comes to shape, there are two primary options for you to choose from: mummy and rectangular.

In most situations, I would suggest using a mummy sleeping bag liner for warmth, as it will hug your body to better trap heat. You can use them inside any sleeping bag, or as a standalone covering if it’s warm out.

Rectangular liners work great in sleeping bags of the same shape, or by themselves if you don’t need much protection. Many travelers will use them when staying in hostels as well, to act as a barrier against any hazards or bedbug infestations.

Liner material

There are a few different options you can choose from when it comes to liner material. Many of these work best in specific environments, but if you already have a liner, don’t feel like you need to purchase a new one just to accommodate a different climate.

  • Silk liners. Lightweight and compact, silk liners are ideal in all temperatures. They add warmth (though not as much as other materials will), but they’re still breathable for use in warmer temperatures.
  • Fleece liners. Much warmer, but the tradeoff is that they’re also heavier. Though they’re quite bulky, they do a great job of wicking moisture away, and they’re one of the most comfortable options. Great for colder weather.
  • Cotton liners. It might not be the lightest option, but cotton is well known for being comfortable, durable, and absorbent. On top of that, it’s also going to be one of the cheapest options out there as well.
  • Synthetic liner. It won’t feel as nice against your skin, but synthetics are great at wicking moisture away, making them an ideal option for more humid climates.

Other Benefits of Sleeping Bag Liners

There’s more to a bag liner than added warmth, though. Depending on what material you go with, a liner can often be far more comfortable to sleep in than the synthetic material of your sleeping bag. Cotton or fleece, for example, will feel a lot more cozy than polyester or nylon!

Additionally, a liner will help you keep your sleeping bag clean. You track a lot of dirt, sweat, and body oils into your bag when you go to sleep at night, and while most bags are machine washable, it does reduce their lifespan. Liners can be washed far more easily and with less consequence, making them a perfect option for keeping everything neat and tidy.

Finally, liners are nice to have when you want a comfortable place to sleep without hauling out your bag. Sometimes it’s just too hot and muggy for a sleeping bag, even if you have it unzipped all the way. Other times, you just might not feel like lugging the extra weight around, so you pack a simple liner instead.

How Do Temperature Ratings Work?

Every liner has a temperature rating on it, typically landing somewhere within the range of 5-15 degrees Fahrenheit. Contrary to what some people initially think, this doesn’t mean that a particular liner will allow you to sleep in temperatures that dip down to that range. Rather, they add 5-15 degrees of warmth onto whatever your sleeping bag is rated.

That means, if your sleeping bag is able to keep you comfortable in temperatures down to 30 degrees, adding a 10 degree liner will now keep you snug down to 20 degrees. This makes them an invaluable asset during winter camping, or when temperatures start to drop lower than you’d like.


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Spencer Yeomans

Spencer Yeomans

A lover of the outdoors, and especially the mountains, Spencer has always enjoyed pushing people to step outside their comfort zones. His mission is to help others get out of their homes to have fun and stay active in nature.

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