Best Sleeping Bag Liners of 2026

Quick picks: the best sleeping bag liners compared

Best overall: Sea to Summit Reactor Fleece

The Reactor Fleece is our favourite. Its soft grid fleece is rated to add up to 8°C to your sleeping bag, and on milder nights it almost works as a summer sleeping bag on its own. A side zip makes it easy to get in and out, and the hood and footbox close with drawcords.

It’s the heaviest and bulkiest of the four Sea to Summit liners, at 379 g and 20 × 13 × 13 cm packed. For car camping and touring that hardly matters, and for $110 it’s the liner we’d pick first.

Warmest: Coleman Stratus Fleece

The Coleman Stratus is the warmest liner here on paper: Coleman rates it to add 12°C inside a sleeping bag, and gives it a 10°C comfort rating on its own. The fleece is soft, the ZipPlow zip doesn’t snag, it’s rectangular with room to move, and the whole thing goes in the washing machine. It cost us only $30.

It’s also the heaviest and bulkiest, at 775 g and 28 × 17 × 17 cm packed, so it’s one for the car rather than the pack.

Warm and compact: Sea to Summit Reactor Extreme

The Reactor Extreme is a soft, stretchy Thermolite Pro mummy liner rated to add up to 6°C. It has snaps at the shoulders and drawcords at the hood and footbox, weighs 350 g and packs smaller than the Fleece.

There’s no side zip, and at $130 it cost us more than the Fleece. If you want good warmth in a smaller pack, it’s the one.

Lightest: Naturehike ZY20

The Naturehike ZY20 weighs only 128 g, packs to the size of a small drink can and goes in the washing machine. It’s long and roomy at 210 × 80 cm, and it costs $35.

The thin nylon adds very little warmth, and there’s no zip: you slide in from the top. Its job is to keep your sleeping bag clean for next to no weight, and it does that well.

Light, adds 4°C: Sea to Summit Reactor Lightweight

The Reactor Lightweight is the lightest of the three Reactors: 286 g on our scale in its stuff sack, and it packs to about 18 × 10 × 10 cm. Its stretchy Thermolite Pro knit is rated to add up to 4°C, with shoulder snaps and drawcords at the hood and footbox.

It’s a little less warm than the Extreme and the Fleece, and there’s no side zip. For a bit of extra warmth on hikes and short trips, at $90, it’s a good pick.

Best for warm nights: Sea to Summit Comfort Blend

The Comfort Blend is the odd one out: a rectangular Coolmax and Tencel liner made to keep you cool, not warm. It’s soft, has a sleeve that holds your pillow in place, weighs 290 g and packs the smallest of the Sea to Summit liners. It cost us $60.

It adds no real warmth and has no zip. For hot nights, travel and a clean layer between you and the bedding, it’s the one.

How to choose a sleeping bag liner

Start with what you want the liner to do. Every liner keeps your sleeping bag clean, but only some add warmth: a thin nylon liner adds next to nothing, a Thermolite knit adds a few degrees, and fleece adds the most. On hot nights you want the opposite, a liner that keeps you cool.

Then think about where it travels. In the car, the weight and size of a fleece liner don’t matter much; in a pack, every 100 g counts. Shape matters too: a mummy liner follows a mummy bag without bunching up, while a rectangular one gives you room to move and suits a rectangular bag or a mattress in the rooftop tent. Sleeping bag liners come in three types:

• Keep it clean

  Little warmth

  Thin and very light. Keeps your bag clean on hikes and travel.

  Weight

  Under 200 g
  Like

  Naturehike ZY20
• Add warmth

  4–12°C added

  Thermolite or fleece. Makes a three-season bag good for cooler nights.

  Weight

  About 250–800 g
  Like

  Reactor Fleece, Coleman Stratus
• Keep cool

  No warmth added

  Soft, wicking fabric for hot nights and a clean layer when travelling.

  Weight

  About 300 g
  Like

  Comfort Blend

Need a sleeping bag to go with it? See our Sea to Summit Boab review.