10 Best Sleeping Bag Liners 2026 in the United States

The Sea to Summit Reactor Sleeping Bag Liner in Extreme Standard size (85 x 31.5 inches) is designed to add significant warmth—up to 25°F—to your existing sleeping bag, making it a solid choice for winter campers or anyone facing cold conditions. It uses advanced Thermolite Pro fabric, which is lightweight yet insulated, thanks to hollow fibers that reflect body heat back to you. This material also stretches well, allowing good freedom of movement inside mummy-shaped sleeping bags.

The liner's drawcord footbox is a feature that lets you adjust ventilation or snugness at your feet and works seamlessly with certain Sea to Summit sleeping bags. Another practical plus is the HeiQ Fresh odor control treatment, helping the liner stay fresh even after multiple uses, which is advantageous when washing opportunities are limited. Weighing just 0.38 kg, it’s fairly light and compact for backpacking.

While it excels in warmth and hygiene, the price point is higher than simpler liners, and the fixed size may not fit everyone perfectly. Care instructions should be followed to maintain the performance and odor control of the technical fabrics. This liner provides a stretchy, warm, and odor-resistant option that works well in winter and fits mummy bags, with a higher price compared to basic models.

The Sea to Summit Reactor Sleeping Bag Liner is designed to add warmth and hygiene to your sleeping bag, making it a solid choice for campers who want extra comfort in cold conditions. Its Thermolite fabric provides good insulation with hollow-core fibers that trap heat effectively, helping keep you warm even below minus 5 degrees Celsius. The liner’s mummy shape and drawcord footbox allow you to adjust warmth and fit around your feet, which is useful for temperature control during chilly nights.

Measuring 85 by 31.5 inches, it fits most adults comfortably without adding much bulk or weight (just under 16 ounces), making it easy to carry on trips. The material is treated with odor control technology, so it stays fresh longer and reduces the need for frequent washing. Fleece and Thermolite typically wash well but can require gentle handling to maintain insulation. While this liner boosts warmth, it is not a replacement for a heavy sleeping bag in extreme cold, and the drawstring closure may take a moment to get used to for a snug fit.

For people camping in cooler weather who want an easy-to-pack, effective liner that improves sleeping bag performance and hygiene, this is a practical option. Its lifetime guarantee from Sea to Summit adds confidence in its durability.

The Sea to Summit Silk Blend Sleeping Bag Liner is designed to enhance your sleeping experience by adding warmth and comfort to your sleeping bag. Made from a blend of synthetic and silk materials, it offers a luxurious feel and effective insulation thanks to its hollow-core Thermolite Pro fibers. These fibers trap warmth efficiently, and the liner also contains infra red absorbing ceramic pigments to further enhance warmth retention.

The liner includes HeiQ odor control technology, which helps keep it fresh even after extended use, making it ideal for long trips. Another practical feature is the drawcord footbox, which can be adjusted for optimal comfort and is compatible with Sea to Summit sleeping bags' footbox zippers. The liner is lightweight, weighing only 5.28 ounces, and compact, fitting easily into your gear with dimensions of 7.68 x 4.72 x 2.56 inches when packed.

It is available in two color options: Navy Blue and Grey. This sleeping bag liner is best suited for those seeking to enhance warmth and comfort in their sleeping system while maintaining a lightweight and compact setup during their outdoor adventures.