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What is Thermal Underwear Made Of?

What is Thermal Underwear Made Of?

Your thermal underwear can be made of many different fabrics to blends. Your comfort is essential, and finding the suitable material for your thermal underwear is necessary to stay warm and dry. Remember, material matters along with the fit and weight of the material. 

Material Decisions

The fabric you choose for your thermal underwear will prove a crucial decision in your purchase. Do you want your thermal underwear made of a natural material or a synthetic one? Either way, you want this fabric to wick away sweat to stay dry.

The Weight of Your Decision

Most thermals come in a lightweight material. This is your standard long underwear fabric and usually what you’ll find from the majority of brands. However, if you need something heavy-duty, then a midweight or heavyweight fabric can also be found.

Fit for Service

You’ll want a snug fit so the thermal’s moisture-wicking features can work. They need to be in direct contact with your skin to do the job you want them to. That includes keeping you warm and comfortable.

Thermal Materials

As a base layer, most fabrics that thermals are made of will do the job you want them to. If you’re looking for material to consider, the attributes below will help you make a choice. However, if possible, avoid cotton thermals. They’ll absorb and retain moisture which will keep you damp and cold, especially outside.


These are the most popular and most affordable. These are usually made of polyester or are blended with other materials like spandex, rayon, or nylon. They are known to keep you dry with excellent moisture-wicking features. They’re durable and can hold up to wear and tear better than others. Many synthetics are also treated to inhibit odor. This means you can wear them a few days before you have to admit defeat and wash them. They’re also easier on the pocketbook. They’re the most affordable solution, especially if you’re buying more than one pair for you or your family.

Merino Wool

While a natural fiber, these aren’t the itchy thermals of days long past. They are made of ultrafine fibers and blended with materials like spandex for extra stretch and a better fit. They are great at wicking away sweat and moisture and will also keep you cool in warmer weather. While durable, they won’t hold up as well as synthetics. They’re also naturally odor-free and usually won’t need any additional treatments. However, they will cost more but are still worth the purchase if you want a more natural fabric.

Other fabrics like silk are great, but they can cost a lot more and aren’t as durable. If you live an active lifestyle, Merino wool or synthetics will be your best choice. Both will keep you warm, dry, and comfortable.

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