What Is Thermolite Insulation?

Hunker may earn compensation through affiliate links in this story.

Though insulated jackets, coats, sleeping bags and other items made from down feathers are incredibly soft and very warm, down insulation isn't suited to every situation. A down jacket will keep you cozy on a cold fall or winter evening, but if you're going hiking or camping, especially in extreme temperatures, synthetic insulation can be much more effective despite the lower price.

What Is Thermolite Insulation?
Image Credit: AscentXmedia/E+/GettyImages

Thermolite is one of many types of synthetic insulation designed to emulate the feeling of down feathers while providing comparable or even more warmth. It comes in various grades, tailored for use in different environments and for different activities. Often found in Columbia-branded products, the insulation is versatile and comes with a number of benefits.

What Is Thermolite?

Trademarked by the Invista corporation, Thermolite is a synthetic down insulation. Used in outerwear, socks, sleeping bags and other items, Thermolite was designed to emulate the softness of down feathers but improve upon their insulating properties at a reduced cost. Items made with Thermolite tend to be less bulky, warmer overall and better at wicking away moisture than similar items made with down feathers.

Thermolite, like all synthetic insulation, is made of fine polyester filaments spun in a way that creates pockets of air between each fiber to emulate the way that soft down feathers create pockets of warm air to keep birds warm even while wet.

Thermolite in particular uses a unique hollow-fiber design that allows the insulation to trap air inside as well as in between each fiber, enabling the insulation to dry faster while also making the items that use it warmer. This design also makes it significantly lighter than some other forms of synthetic insulation, allowing jackets and other outerwear to be layered to maximize the warmth and comfort of the wearer.

Thermolite Material Types

Not all synthetic insulation is the same. While every type of synthetic insulation is designed with warmth in mind, the different brands and grades excel in different environments and situations. This is why when you are looking for a jacket with insulation, a guide will direct you to different insulation solutions depending on the temperature, season and activity. To provide solutions for as many users as possible, Thermolite comes in a number of variants.

Thermolite's base variant provides lightweight warmth and durability and is designed with general use in mind. Jackets made with this insulation are better suited for fall and early winter use.

The new Thermolite PRO variant, in comparison, provides a higher-end insulation intended for winter sports and activity in extreme temperatures that maximizes warmth and moisture resistance with a fiber design that allows the material to be woven into denim and other fabrics. The third variant, Thermolite EcoMade, prioritizes comfort and a lighter weight paired with water resistance. While it provides less warmth than its sibling variants, it is more durable and is made from recycled materials.

Insulation Ratings and Down Insulation

Products with each Thermolite variant can be found at various price points based on the overall insulation rating. Insulation ratings for synthetic insulations are measured by the grams of material per square meter inside each product. The rating determines the thickness and overall warmth of the item. For example, a jacket with a 60g insulation rating will be half as thick and significantly less warm than a jacket made from similar materials with a 120g rating.

Compared to items made with real down feathers, insulated items made with Thermolite have their costs and benefits. While Thermolite insulation is less expensive, it has a higher warmth per weight compared to down, leading to bulkier items using it. However, down insulation is less suited for active wear and is dramatically less water resistant than synthetic insulation.


Blake Flournoy is a writer, reporter, and researcher based out of Baltimore, MD. As a handyman's apprentice operating out of the Atlanta suburbs, they made a name for themselves repairing appliances and installing home decor. They have never seen Seinfeld and are deathly scared of wasps.

View Work