Fend off Winter Chills With the Best Thermal Underwear

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Jon Snow's forces may have stopped the Night King and his White Walkers; they can't do anything about the march of oncoming winter. Readers who live in the colder parts of the country understand that regular clothing does very little when the temperatures start dropping. You need an extra layer of clothing to keep frost at bay. Enter thermal underwear. 

Thermal underwear is the first layer of clothing that you wear under your regular clothes to ward off cold. They are available in different styles, materials, and weights to find the right one for your needs. But choosing one is not as simple as grabbing the first one you see. 

Today, we'll tell you about the top-selling thermal underwear of 2024. No matter what your style of undergarments may be, there will be something for you. Plus, there is a shopping guide included to help you out. 

Detailing the Top Thermal Underwear of 2024

Thermajohn Thermal Underwear  —  Best Overall

Thermajohn Thermal Underwear is one of the most functional pieces currently available out there. Featuring a blend of 92% polyester and 8% spandex, these thermal underwear rank high both in terms of toastiness, comfort,  and flexibility. The material is odor-resistant and moisture-wicking. Plus, it also hugs close to your body for adequate temperature regulation. We also like it for its functionality. The men's style features a traditional front fly opening for quick restroom trips, while the machine washing makes cleaning easier. It made it to the top of our list for its lightweight yet stretchy material that keeps you from feeling like a sausage trapped in a casing. The amazing material and size variety has made it our top pick overall.


  • Available in eight different sizes 
  • Easy to care for
  • Offers full flexibility and body movements


  • Sizes run a bit small

Weerti Thermal Underwear for Women  —  Most Flexible

Looking for a classy yet warm set of underwear that helps you brave the cold without discomfort? Let us present the Weerti Thermal underwear for Women in all its streamlined, elegant glory that should be enough to keep you warm even on the coldest nights without compromising on style.

This incredibly flexible set of undergarments is lined with fleece for that extra protection from cold winds and comes with a cozy set of lightweight but warm long johns to provide that extra security for your bottom half. Their true size snug fit nature also ensures no bunching around your waist, allowing you to walk around freely without having to adjust yourself constantly.


  • High-quality fabric guarantees comfort 
  • Efficient moisture transport system
  • Stylish and streamlined design
  • Manufacturers offer complete refunds and replacement


  • Sizes may be a little inaccurate

Amazon Essentials Thermal Underwear  —  Budget Pick

Our next pick is an affordable set of thermals from Amazon Essentials. This long underwear set features a natural synthetic hybrid material, consisting of 60% cotton and 40% polyester. The material is lightweight and extremely breathable, so you won't feel weighed down. You also won't feel any friction when layering it, as the material is smooth. It is a solid set that is both warm and slim fitting. The ribbing along the wrist and neck also ensure proper fit while preventing the body heat from escaping. You can choose from a range of sizes, and it is also available in six color options. 


  • Cotton blend material is extremely breathable 
  • Fits true to size
  • Lightweight and very comfortable 


  • Can shrink in wash 

Fruit of the Loom Thermal Underwear  —  Eco-Friendly Option

This Fruit of the Loom Thermal Underwear is an eco-friendly option because it utilizes recycled polyester in its fabric blend. It is 52% cotton and 48% polyester woven into mini waffle fabric for softness and elasticity. The cotton is all sourced from within the US. It makes this thermal top and bottom extremely breathable. You can wear it from moderately cold to extremely cold conditions without feeling the chills. It is available in four neutral colors and a wide range of sizes. We also like the ribbed cuffs and neck that prevent heat loss, and the flatlock seam that ensures years of wear without a rip. 


  • Made using recycled polyester 
  • Tag-free design ensures true comfort 
  • Ribbed cuffs prevent heat loss 


  • One of the more expensive options 

CL convallaria Thermal Underwear  —  Best Value for Money

Our next pick gives you the best bang for your buck because it is a set of two thermals. This CL convallaria Thermal Underwear set has warm base layers with fleece lining to retain body heat. They feature a blend of 90% polyester and 10% spandex in their construction. The extra percentage of spandex makes them incredibly flexible and stretchy. They are soft on your skin and fit snugly to minimize heat loss. Since they are highly breathable, they won’t make you feel sticky or clammy. You can keep these on for an entire day of outdoor activity without feeling cold. Plus, there are no labels to irritate your skin making these the comfiest option so far.


  • Come as a set of two
  • Does not fade or shrink 
  • Insulated design minimizes static 


  • Available in four sizes only 

WEERTI Thermal Underwear  —  Most Inclusive

WEERTI Thermal Underwear is a top selling option at online marketplaces. This set ensures all day comfort with its 92% soft polyester and 8% spandex blend material. The fabric is extremely soft to touch and wear with a fleece lining that helps you stay warm on the coldest of days. This top and bottom is also quite breathable and moisture-wicking. Their moisture transport system quickly wicks the sweat away so you feel light and dry. This feature alone makes it a top contender because quick drying means you won't feel clammy even during the pursuit of your active lifestyle in the cold outdoors. We really like it for its inclusive size range.


  • Comes with a money-back guarantee 
  • Ensures full mobility with 4-way stretch fabric 
  • Quick at wicking moisture 


  • Not true to size

Buyer's Guide To Finding the Right Thermal Underwear

Thermal underwear keeps you warm by using the heat your own body produces. By covering your skin, it prevents the body heat from escaping into the air and keeps it within a few millimeters of your skin. That's why you must find one that fits right and is insulating enough for your needs. Here's a buyer's guide to help you find the right pair:

Types of Thermal Underwear 

Thermal underwear is categorized into various types according to the material they are made from. The primary materials used in their manufacturing are wool, cotton, and silk. But you can also choose a pair of synthetic thermal underwear as well.  Let's see how they vary in terms of performance:

Wool thermal underwear 

Wool thermals are a much-favored option because of their amazing thermal qualities. But you have to choose a high-quality fiber like merino wool. Low-quality wool works too, but can irritate sensitive skin. The material has been around for centuries and has been used for making warm clothes. 

Woolen thermal wear does an excellent job of keeping you warm. What truly sets it apart is the material's ability to quickly dry and not get wet. It can absorb 30% of its weight in water without appearing wet. Plus, this type of thermal wear is readily available with numerous manufacturers' lineups. 

Cotton thermal underwear 

Cotton thermal wear is also an easily available type, but it loses its heat retaining ability when it becomes wet. As soon as you start working out and sweating, the thermal layer it creates starts becoming compromised. That said, cotton thermals are usually available for very affordable prices too.

Silk thermal underwear 

Silk thermal underwear is exactly what you expect, smooth and extremely comfortable. Seeing silk is a cool material you are right in wondering how it is getting along with thermal underwear. Well, these are made using a tight and heavy knit to achieve the warmth level you are looking for. This kind of knit is very effective in retaining body heat, but also makes the garment costly. Regardless, silk thermal underwear is one of the most comfortable and moisture-wicking options. 

Synthetic thermal underwear

Synthetic thermals are crafted with a blend of two or more man-made materials, such as nylon, polyester, and elastane. Some companies also mix wool in their blend too. There is no specific percentage for the blending materials, rather each manufacturer adjusts its specific blend. These are engineered to be soft, comfortable, and moisture-wicking. 

Factors To Consider in Thermal Underwear 

When it comes to choosing the fabric of your thermal underwear, both wool and synthetic blends take the lead. Cotton isn't the best choice for sweating when you are outdoors, and silk thermals are rather expensive. Now that we have chosen the material, let's see what other factors you should consider in a good set of thermal underwear. 


Thermal underwear helps you stay warm by trapping your body heat between itself and your skin. It creates a small gap between both the layers in which the heat accumulates at a relatively consistent temperature. You can compare the feeling to that of being inside your own temperature-regulated bubble. But in order to be effective, the thermals need to fit well. 

It should be a relaxed fit but not loose enough to appear bulky. You need a set that is trim and layers well, not necessarily skin-tight. But you also don't want it to hang loose. The sleeves should be long enough to cover your wrists and the hem shouldn't ride up your back when you bend down. These are the areas where most body heat is lost. 


The base layer is supposed to keep you warm, but without making you feel uncomfortable. Look for comfortable design features such as flatlock seams and offset shoulder seams. These are helpful when you have a backpack on and its shoulder straps cause the seams to rub against or dig into your shoulders causing discomfort. Several thermal underwear options feature a raglan or offset sleeve specifically for this reason. It is also important that the option you choose does not restrict movement or cause itching. 


This factor does not need much explanation. If you are planning to ski in the Arctic, your set of long underwear will be quite different than the one that you don when skiing the Midwest in mid 30 degree weather. When looking at the different options, think about the setting you will be wearing it in. If you are planning to wear it as lounge wear in a heated house, a set of base layers will do. But if you want to wear it as an additional layer when you hike on a cold morning, you'll need a warmer set of thermals.