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Which sleeping bag liner should I choose?

Which sleeping bag liner should I choose?

The humble sleeping bag liner might be one of the most underrated pieces of camping gear out there.

This unsung hero of the sleep system can do everything from boosting the warmth of your sleeping bag to increasing its usable lifespan.

To get the most out of your sleep system set-up, we’ve compiled the ultimate guide to sleeping liners—why to use one, how to pick one and how to care for it.

WHY USE A sleeping bag liner?


You use a sleeping bag liner for the same reasons you put sheets on your bed—hygiene. You probably don’t sleep directly on your mattress or down quilt because they’re a whole lot harder to get clean than a set of sheets.

Out in the wild—in the grimy world of hiking and action-packed adventures—this problem can be tenfold as you bring a day’s worth (who knows, maybe several weeks’ worth) of sweat, dirt and B.O. into your sleeping bag. A sleeping liner is a much-needed barrier that can significantly raise your hygiene standards on the trail. After all, it’s much easier to clean a liner than it is to wash a down sleeping bag or synthetic sleeping bag.

protect your sleeping bag

Using a sleeping liner will increase the life of your sleeping bag. The build-up of oils from your skin can migrate into the down or synthetic fill of your sleeping bag—preventing it from fully lofting and keeping you warm. And who wants to pay for a high-quality sleeping bag only to halve its performance?

The sand that you bring into a sleeping bag can also work its way through the lightweight face fabric. Once these small grains make their way into the insulation, they can act like sandpaper and damage the down or synthetic fill.


Even lightweight hikers often make room in their packs for a sleeping liner simply because it improves their chances of getting comfy and cozy on the trail. We focus a lot on comfort when it comes to our sleep systems—because it’s the thing that helps you doze off in unforgiving terrain. And in high-stakes situations—like mountaineering, climbing, white-water rafting or paragliding trips—you need your wits about you. You need your sleep.

Comfort is relative, of course—it could be the smooth feel of a silk liner or the legroom a rectangular fit provides (we even have an extra-wide, if that’s your bag). Either way, consider what’s comfortable for you and make it a priority.

add warmth to your sleeping bag

A sleeping liner can add a few degrees warmth to your down or synthetic sleeping bag. Our THERMOLITE® Reactor Liner can add up to 14°F and even a thin Cotton Liner traps an extra layer of air to help insulate.


Our Spark Ultralight 0 Down Sleeping Bag has a comfort level of 50°F and the regular weighs only 7.9 oz. Pop this in your bag to radically boost your sleeping temperature—or use it on its own in warmer weather.

use in sketchy hostels, huts or couch surfing

A big bonus of a sleeping bag liner is that it can serve as a handy travel sheet. Protect yourself from dodgy looking hostel bunk beds or generously offered (but slightly grubby) couches. In summer, a sleeping bag liner can even be used as a standalone sleeping bag.

choosing the right sleeping liner

end use

If you’re trying to extend the warmth of your sleeping bag, a THERMOLITE® Reactor™ Series liner is going to add the most degrees to your bag. THERMOLITE® is a hollow core fiber that traps air so when it’s knitted into fabric, it holds heat in the actual fiber as well as the looped structure of the knit. For this reason, it gives greater warmth-for-weight compared to most liners out there.

If you’re priority is cleanliness, any of our liners will fit the bill—you’ll just have to factor in which weight, packed-size, shape and fabric is right for you.

weight and packed size

Think about what you realistically can carry on your next trip and choose the best option within that weight and size range.

If pack space and weight is at a premium for your next trip, an ultralight and compact Silk Liner (4.8 oz for the tapered mummy version) could fit the bill. Willing to take on a few more grams for a toasty warm sleep? Then 8.7 oz for a Reactor™ Liner is totally worth it.

fit and construction

Our travel liners come in a Standard or Long Rectangular fit, Double, Mummy, Mummy with Hood and Traveller (with pillow insert). Our technical liners are a tapered mummy shape. The best rule of thumb is to choose a liner shape that best fits the shape of your sleeping bag. Or if you’re more swayed by handy construction features—we have liners that come with hoods, pillow inserts and comfort stretch panels.

how to wash your sleeping bag liner

Easily. All our sleeping liners are machine washable and require only your standard laundry detergent. If you’re using a top-loader washing machine, place the liner in a pillowcase or laundry bag first to stop any cords being caught up in the impeller.

Steer clear of fabric softeners when cleaning your liner as they can affect the wicking properties of the material. 

To dry your liner, it’s best to hang it on a washing line to air dry. Using a dryer could expose it to excessive heat, which can damage the fabric.

which liner is best for me?

add warmth to your sleeping bag: reactor series

If your sleeping bag needs a thermal boost for a particular trip, check out our THERMOLITE® Reactor Series. You can even use a Reactor as a stand-alone summer ‘sleeping bag’.

Our THERMOLITE® Reactor Fleece Liner is pure toasty luxury—offering both warmth and an incredibly soft next-to-skin feel.


Silk Liners wick moisture and are quick to dry. The Mummy shape is suited for backpacking and the Traveller is a great addition to hostel living. Our Premium Silk Liners have Comfort Stretch Panels along the length of the seam, which helps the liner move with you as you turn.


Silk + Cotton Liners are great for the same uses as pure silk liners—but their less-shiny surface makes them slightly more grippy. A solid choice for restless sleepers who might get tangled in a pure silk liner.


COOLMAX® Liners wick moisture and dry quickly. They’re also really stretchy—so if you’ve ever felt constricted in a liner, this is the answer. Available in both a Mummy shape and a rectangular Traveller version with a pillow insert.


If packed volume and weight is less of a concern, the Expander Liner is a luxurious addition to your sleep system. The jersey knit construction stretches to almost twice their normal width they don’t have side seams to contend with (with the exception of the Mummy shape). These premium liners also feature an anti-microbial treatment that won’t wash out of the liner, keeping it odor-free.

which liner do you need for your sleep system?

Visit our Sleep System Finder to build a sleep system that’s tailored to you.

20 thoughts on “Which sleeping bag liner should I choose?

  1. avatar Baz says:

    G’Day Steven –

    Sorry it is proving tricky to get your Silk Liner back into its pouch. We switched to the current zippered pouch around 10 years ago as a result of demand from retailers for a slimmer storage bag – we may still have some of the original stuff sacks in stock. If you email us at and let us know your shipping address, we will be happy to find a roomier stuff sack for your liner.


    The Sea to Summit team

  2. avatar Steven says:

    Why package the “Traveller Premium Silk Liner” in a pouch that’s too small to reuse? The pouch is nicely made, with net venting, a zipper, and the SEATOSUMMIT logo and description of the liner prominently displayed, but I’m discarding it because it’s impossible to fit the liner back into after use.

  3. avatar Baz says:

    Thanks for reaching out to us, Stephen. The short answer is that many AT Thru-Hikers use the Silk Mummy Liner or the slightly heavier Adaptor Liner. The longer answer is that a Thru-Hike is an undertaking that spans several months and a lot of different climatic conditions. In order to make recommendations, it would be very helpful to know what type of sleeping bag and sleeping pad you will be using – please email us at and let us know; we’ll be happy to assist you further.

  4. avatar Stephen Pullen says:

    Me and the daughter are planning to thru hike the AT this spring. Just wondering which one would be the best. It’s a several day trip. So weight is a issue. I expect it’ll be colder at night sense it’s early to mid spring. So any help would be great.

  5. avatar Baz says:

    Hey Erland,

    Thank you for reaching out to us! I would say that either length of liner would work for both of you. The more important question would come down to how much warmth you want the liners to provide to your sleep systems and how much additional weight you are willing to carry. We cut the liners long to ensure ease of entry/exit and additional room to ensure you don’t feel claustrophobic (the knit fabric is extremely stretchy, still). The remaining length can be tucked under or on top of the feet for more warmth, the excess should not affect the performance.

    The Reactor Compact Plus has 110 grams/m2 of Thermolite material in the torso and foot areas and 80 grams/m2 in the waist/head with 183cm length. Packed size is 15×11cm @ 263 grams.

    The Reactor Extreme has 110 grams/m2 of Thermolite throughout the entire liner with 210cm length. Packed size is 17×11.5cm @ 399 grams.



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