10 Best Sleeping Bag Liner For Warmth 2025 in the United States

The Sea to Summit Reactor Sleeping Bag Liner in Fleece Compact is designed to enhance the warmth and hygiene of any sleeping bag, making it a valuable addition for camping, hiking, and backpacking enthusiasts. Made from hollow-core Thermolite EcoMade fibers in a grid-pattern fleece, it efficiently retains heat, which is ideal for three-season use with a temperature rating of 32F and above.

The liner features a mummy shape for maximum thermal efficiency, shoulder zippers, and a drawcord footbox that can be opened or closed for personalized comfort. Additionally, the HeiQ Fresh odor control technology ensures the liner stays fresh even after extended use, which is a great plus for long trips. It is also compact and lightweight, weighing just 0.92 pounds and measuring 78 x 31.5 inches, making it easy to pack and carry.

However, while the thermal boost and odor control are beneficial, some users may find the polyester material less breathable compared to natural fibers. Also, its dark blue or black color options are limited. The product is backed by the Sea to Summit Guarantee, adding a layer of reliability. This sleeping bag liner is best suited for adults who need extra warmth and hygiene on their outdoor adventures.

The Sea to Summit Reactor Sleeping Bag Liner is designed to add extra warmth and hygiene to your sleeping setup. With its Thermolite Pro technology, it efficiently reflects your body heat, making it ideal for three-season use, with a temperature rating between 31 to 45 degrees Celsius.

The liner is made from Thermolite Pro and EcoMade Polyester, providing a good balance of warmth, comfort, and stretch due to its knitted fabric, making it flexible and comfortable to move around in. Its drawcord footbox is a practical feature that can be adjusted for comfort and fits well with certain Sea to Summit sleeping bags.

Additionally, the HeiQ Fresh odor control technology is a significant advantage for maintaining freshness during extended trips. The liner is lightweight, weighing just 0.67 pounds, and its compact size makes it easy to carry in your camping gear. However, while it offers good warmth, it may not be sufficient for extremely cold conditions. The bright yellow color might not be appealing to everyone, and though it is easy to care for, being made of synthetic materials, it may not offer the same natural feel as cotton or silk liners. This product is best suited for campers and hikers who need a reliable and easy-to-care-for sleeping bag liner for moderately cold conditions.

The Litume All Season Fleece Sleeping Bag Liner is designed to add extra warmth to your sleeping bag, boosting its temperature rating by up to 27°F (15°C), making it an excellent choice for cold weather camping and winter backpacking. Made of soft polyester fleece, it feels comfortable against the skin while remaining lightweight at just over 1 pound (about 510 grams). Its mummy shape with a drawstring hood helps lock in heat, and the foot box offers more room for your feet, enhancing comfort. At 85 by 32 inches, it’s roomy enough for most adults, including those up to 7 feet tall.

The liner is machine washable and compressible, making it easy to clean and pack into the included travel sack without taking up much space. While the fleece fabric is warm and cozy, it may not be as breathable as some natural materials, which could lead to feeling a bit sweaty in milder conditions. Additionally, its dark grey color might show dirt more easily than lighter options.

This liner suits campers or travelers seeking an affordable, easy-to-carry way to increase their sleeping bag's warmth, especially in cold environments. For those looking for a lightweight, effective all-season liner with simple care, this option is definitely worth considering.