best thermal underwear
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When the last autumn leaves fall, it’s a sign that winter is around the corner. As the days get colder, you may need to bundle up or layer more clothing layers to beat the chill and frost. And, what’s the best way to do that?

Well, most people put on more layers of outer clothing. And this may get cumbersome as you compromise your ability to move and thermoregulate. So, what you need to consider is getting the best thermal underwear you can find on the market.

The unsung benefits of Thermal underwear keep on rolling the more you think about it. Stay tuned as we go over some of the best thermal underwear.

What Should You Consider Before Buying The Best Thermal Underwear?

Your first consideration should be the type of activities you wish to participate in during the winter months. Fortunately, Thermals are constructed in a manner that compliments your need for mobility.

Here are a few broad classifications to guide you to the best choice:

Every day-wear thermals are soft, warm, and comfortable to even sleep in. They are usually made of a synthetic/natural material blend. This ensures the base layers keep you toasty warm as it wicks away moisture from your skin.

Activewear thermals have a thicker base layer. They offer some joint compression and fit a bit loosely on the chest area, which prevents cramping. This ensures that you have all the versatility you need for activities such as mountain climbing or canoeing.

Snowsports thermals feature heavy-light base layering. The cuffs and neck are to a compression fit, and they have good moisture-wicking qualities. This protects you from harsh winds and keeps you dry as you ski, snowshoe, or participate in other winter sports.

All-weather thermals are made with the motorcyclist in mind. They are not only meant to shield you from the cold but also high-speed winter winds. Their heavy base layers are a result of thick synthetic fibers merged with a waterproof membrane.

Brief Overview on Top Thermal Underwears in 2021

What’s The Warmest Thermal Underwear?

It’s tough picking a hand-down favorite even after hours of research and product testing. So here are X of the best thermal underwear for your discerning pleasure.

Smartwool Merino 250 Men’s Wool Active Thermal

Smartwool Men’s Base Layer Top - Merino 250 Wool Active Crew
  • Material: 100% merino wool
  • Brand: Smartwool
  • Colour choice(s): 8
  • Style: Long-sleeve pullover crew-neck

Let’s kick off things with one of the highest-rated thermal long-sleeves on the market. The Smartwool Merino 250 Men’s Wool Active Thermal tops will serve you in warm as well as cold weather. These thermals meet a +50 UPF rating, which means they can also double up as rush guards. So, you can use them for water sport in temperate climatic conditions.

The genius combination of flatlock seams and Merino wool ensures zero cold spots. So, they offer adequate insulation from cold weather and windy conditions. These midweight Smartwool Merino 250 Men’s Wool Active, Thermals, are machine wash friendly so they won’t shrink or pile. Best of all, you can also buy a matching pair of thermal bottoms from the same series to enhance your styling options.


  1. Soft
  2. Warm and water-resistant
  3. Moisture wicking and anti-odor properties


  1. Premium price point
  2. Requires loads of detailed care

Patagonia Capilene 3 Midweight Zip-Neck Top Thermals

Patagonia Men's Capilene 3 Midweight Zip Neck (Medium, Black)
  • Material: 100% diamond-grid double knit recycled polyester
  • Brand: Patagonia
  • Colour choice(s): Alaska Blue
  • Style: Long sleeve crew-neck jersey

Next on the list is yet another crowd favorite. The Patagonia Capilene 3 Midweight Zip-Neck Top Thermals come in a compression fit that makes them look fantastic, whether worn as a base layer or as a jacket. This doesn’t mean they’ll fit lose as their construction features Polartec Power Grip. Such technology gives these thermals unique moisture-wicking properties as well as breathability.

Aside from keeping you dry, you’ll also stay warm and have unrestricted movement. Another notable innovation to these Patagonia Capilene 3 Midweight Zip-Neck Top Thermals is a center front zipper. Such a feature allows you to vent heat when it gets sweaty under the hood. The underarms are gusseted, while the shoulders feature a raglan seam. This ensures your mobility remains at an optimum in any activity.


  1. Has a men’s version
  2. As durable as merino yet cheaper
  3. Features HeiQ anti-odour technologies


  1. Not soft
  2. Sizes run small

Women’s Plus Size Long Johns Thermal Underwear Set

Women’s Plus Size Long Johns Sets 2 Pcs Base Layer Sets Thermal...
  • Material: 95% Rayon, 5% Spandex
  • Brand: In’Voland
  • Colour choice(s): 9
  • Style: Long Johns

These Women’s Plus Size Long Johns Thermal Underwear Set from In’Voland take the price for body positivity. Sizes run from 16 plus to 22 plus, which means every big girl can layer up and stay warm in cold weather. They fit so snuggly that you can wear them as pajamas. You can also layer them under clothing to frolic in the snow.

This Women’s Plus Size Long Johns Thermal Underwear Set is breathable and has no gaps or cold spots. So you won’t sweat that much while indoors or outside in the cold weather. These thermals make a stylish choice with their long sleeves, compression fit, and elegantly round neck-line. If you like accessorizing, you’ll be delighted in their wide selection of bold and subtle color options.


  1. High tear resistance
  2. Anti-pilling stitching
  3. Compression fit for shape retention and anti-chafing


  1. Low neck-line
  2. Sizes run wide

Thermajohn Men’s Ultra Soft Thermal Underwear

Thermajohn Men's Ultra Soft Thermal Underwear Long Johns Set with...
  • Material: 87% Polyester & 13% Elastic Jersey
  • Brand: Thermajohn
  • Colour choice(s): 5
  • Style: Thermals set (Long pant + long sleeve top)

Thermajohn Men’s Ultra Soft Thermal Underwear is woven in argan oil. This gives it the same soft feel you get when swaddled and bundle in premium cotton. Since it’s polyester, you get a 4-way stretchiness that won’t compromise your flexibility. Such material construction also gives these Thermajohns insulating qualities that shield you from the cold and winds of winter.

It wicks moisture away from your skin, keeping you dry. But, even if you sweat, you’ll be glad you donned this set as it has odor-resistant qualities. This makes it ideal for those that have sensitive skin. If you like having his and her sets, then you can get your significant other Thermajane to compliment your choice.


  1. Ultra-soft inner fleece
  2. Compression fit waistband
  3. 4-way stretch for a perfect fit


  1. Tends to shrink
  2. Sizes run slim

Thermajane women’s Ultra Soft Thermal Underwear

Thermajohn Men's Ultra Soft Thermal Underwear Long Johns Set with...
  • Material: 87% Polyester & 13% Elastic Jersey
  • Brand: Thermajane
  • Colour choice(s): 10
  • Style: Thermals set (Long pant + long sleeve top)

The Thermajane women’s Ultra Soft Thermal Underwear doesn’t only complement their Thermajohn counterparts in style. They are also a hot-selling commodity on Amazon. This is because they are made from soft and stretchy materials that offer a decadent level of comfort. They are lightweight, breathable, yet highly effective at wicking moisture away from your skin.

They fit snuggly, and sizes run from XX- small to 3X- large, which means anyone can own a pair. These Thermajane thermals offer compression that compliments your figure. Such qualities make them as unrestrictive as Lycra alternatives. You also get a wide selection of colors that can complement all your outfits.


  1. Ultra-soft inner fleece
  2. Compression fit waistband
  3. 4-way stretch for a perfect fit


  1. Tends to shrink
  2. Sizes run slim

Rocky Men’s Waffle Thermal Underwear Long John Set

Rocky Thermal Underwear for Men Waffle Thermals Men's Base Layer Long...
  • Material: 65% Cotton 35% Polyester wicking microfibers
  • Brand: Rocky
  • Colour choice(s): 22
  • Style: Thermals set (Long pant + long sleeve top)

Why spend a boatload on thermals when you can get these Rocky Men’s Waffle Thermal Underwear Long John Set for a steal on Amazon? This set comes in a slim fit, which makes them ideal for use as a base layer. The polyester material wicks moisture, while the soft cotton fleece lining makes them as soft as a second skin.

One other feature worth mentioning is the fly opening that makes life easy when you need to visit a washroom. The Rocky Men’s Waffle Thermal Underwear Long John Set features minimal seams and zero tags, which means they are chafe-free. Sizing runs from small to 6X-large, so all you need is to consult their size charts for the perfect fit.


  1. Lightweight yet warm
  2. Features zero cold spots
  3. Stretchy for a compression fit


  1. A bit thing for frigid weather
  2. Develops runs if used in rough conditions

Duofold Men’s Mid-Weight Wicking Thermal Bottoms

Duofold Men's Mid-Weight Wicking Thermal Pant
  • Material: 60% Cotton, 40% Polyester
  • Brand: Duofold
  • Colour choice(s): 5
  • Style: Thermal bottoms

These Duofold Men’s Mid-Weight Wicking Thermal Bottoms offer a primo range of insulation from cold weather at a fair price. They are made from 60% cotton, which makes them soft yet flexible. The other 40% is polyester, which adds moisture-absorbent qualities to a perfect fabric blend. Duofold has also worked their magic to give it anti-microbial properties.

This means things won’t get too musky or wet as you move around in these thermals. If you have sensitive skin, then these are the base layer pants for you. They come with tag-less labels and flatlock seams that prevent chafing, no matter how active you are while these thermal bottoms. It may be wise to layer them under clothing as they offer little protection from chilly winds.


  • Can also be worn as regular pants
  • 2-ply cotton prevents chafing
  • Rib-knit cuffs for a compression fit


  • Thermal top sold separately
  • Sizes run large

Men Thermal Performance Underwear Set by Outland

Men Thermal Performance Underwear Set by Outland; Base Layer; Soft...
  • Material: 92% Ultra Soft Polyester, 8% Spandex
  • Brand: Ultra Dry
  • Colour choice(s): 7
  • Style: Thermal top & bottoms set

This Men Thermal Performance Underwear Set by Outland offers you full body thermal protection. The polyester used in this suit is so thin that it feels like a second skin that wicks moisture away from the skin. Its material construction also features spandex that’s stretchy enough to give you the versatility you need to work or play in cold weather.

This top-down set features microfibers that give it the same qualities as natural fabrics. It should last you through many winters you wash and take good care of it. Its only shortcoming is it’s a lightweight option. This means the Men Thermal Performance Underwear Set by Outland won’t serve to be useful if exposed to sub-zero temperatures for an extended period.


  1. Features moisture-wicking microfibers
  2. Elastic for a compressive fit
  3. Top and bottoms not sold separately


  1. Ineffective in sub-zero temperatures
  2. Needs detailed care

CL convallaria hunting thermal underwear set

Thermal Underwear Set Winter Hunting Gear Sport Long Johns Base Layer...
  • Material: 91% Polyester, 9% Spandex
  • Brand: CL convallaria
  • Colour choice(s): Army Green & Army Green with Black Trims
  • Style: thermal underwear set

Do you like to add a tactical styling to your thermal base layering? Then the CL convallaria hunting thermal underwear set may exceed your expectations. It comes in an army green color with minimal design trimmings. This set not only looks terrific, but it’s also hypoallergenic and comfortable to boot! This CL convallaria model features a polyester/spandex blend. Such materials ensure adequate insulation in cold weather.

This material blend is knit to a 4-way stretchiness that allows for unrestricted movements. So, you can layer it under your clothing while on winter activities like hunting, skiing, mountaineering, and so on. The CL convallaria hunting thermal underwear set is not only breathable but also insulates you from harmful UV rays and blistering winds.


  1. Cosy & lightweight
  2. Pants feature a pocket
  3. Suitable for sub-zero climate


  1. Pant leg sizing runs long
  2. Unsuitable for short or overweight people

Duofold Men’s Mid Weight Double-Layer Thermal Union Suit

Duofold Men's Mid Weight Double Layer Thermal Union Suit, Red, Medium
  • Material: 65% Cotton, 25% Merino Wool & 10% Nylon
  • Brand: Duofold
  • Colour choice(s): red, black & Oatmeal Heather
  • Style: Onesie

This list would be incomplete without at least one classic union suit. If you like onesies, then the Duofold Men’s Mid Weight Double-Layer Thermal Union Suit is worthy of your consideration. It has two insulating thermal layers. That serves to enhance your comfort without compromising your flexibility and comfort. The outer layer features cotton, nylon, and wool. At the same time, the interior is soft cotton fleece.

Such materials make it stretchy enough to allow unrestricted movements as you work, play or relax in cold weather. These one-piece thermals are comfortable, so you can even sleep in them. The Duofold Men’s Mid Weight Double-Layer Thermal Union Suit offers ultra-insulation without compromising on its breathability. This is because it has no gaps or cold spots, and the material blend wicks moisture away from your skin. The only drawback is you may experience challenges as you have to doff off the top part when you need to visit the bathroom.


  1. Fair price point
  2. Offers full body protection
  3. Suitable sleeping in and short term cold exposure


  1. Unsuitable for long term protection
  2. Low moisture-wicking qualities

Best Thermal Underwear: FAQs

1. What is the Best Material For Thermal Underwear?

The best thermal underwear is made of the following materials:


Cotton is the most common material featured on base layers. For one, it’s soft to the touch and ultra-absorbent, and super warm. Modern cotton fiber blends also make for odor-resistant and anti-microbial thermals.


Silk is quite expensive but makes clothing that’s ideal for people with sensitive skin. These days, silk can be blended with synthetic fibers to enhance its natural hypoallergenic and moisture-wicking qualities. The only major drawback is silk thermals need loads of care as they can trap sweat that can breed mal-odorous bacteria.

Polyester Fabric blends

Polyester is one of the most significant innovations in fabrics like on others. It gives base layers that stretchy quality that makes them feel like a second skin. They also produce clothing that’s warmer, more resistant to foul odor and sweat accumulation.

Polyester comes in so many combinations, so here’s a short list of some of the most popular blends:

  • Ethylene Polyester
  • PCDT Polyester
  • Plant-Based Polyester

Merino wool

Most manufactures prefer Merino wool since it’s softer and less itchy than traditional wool. Merino wool is super warm and stretchy when blended with other fabrics. Merion thermals are also absorbent, so they are ideal even when it gets a bit warm.

Synthetic fibers

Most of the products feature waistbands made from synthetic materials. This includes Lycra, Spandex, and so on.

2. What Are The Best Cold Weather Thermals?

Base layer thermals are categorized according to their weight. The best cold weather thermals are anything from midweight to heavyweight fabrics. So, you can never go wrong with a cotton blend or thermals made from authentic merino wool.

3. Which Men’s Thermal Underwear Is Best?

As you can see from our list, there are many ideal thermal underwears to choose from. With that said, Patagonia Capilene 3 Midweight Zip-Neck Top Thermals rank as the most functional thermal tops you could buy.

The Smartwool Merino 250 Men’s Wool Active Thermal also hit the market with stellar reviews. Duofold Men’s Mid Weight Double-Layer Thermal Union Suit will serve you if you like the classic feel of onesies. But, you can’t go wrong with any of the products on our list.

4. Can Thermals Be Used Instead Of Conventional Underwear?

It comes down to the kind of activity you wish to partake in your thermals. For instance, you can skip donning undies if you are in a rush to get to the gym or out for a run. However, It’s wise to keep the undies on to reduce chafing or for thermals that don’t cover your crotch effectively. Undies also add an extra layer of clothing and prevent the thermals from getting too dirty as you work and play.

5. Why Should I Consider The Moisture-Wicking Qualities Of Thermal Underwear?

Most people assume you shouldn’t worry about sweating when bundling up for the winter. However, you’ll still sweat underneath all those layers of clothing. Therefore, it may be wise to consider thermals that wick this moisture away from your skin and redistributes it to the seams.

Moisture-wicking thermal tops can also work as rush guards when surfing, swimming, or having fun in warm weather. Some like Smartwool Merino 250 Men’s Wool Active Thermals feature a UPF factor of +50 that protects you from harmful UV rays.

6. What’s The Best Sizing for Thermal Underwear?

The short answer is not too constrictive or baggy. If your thermals are too tight, they may make it hard for you to move or vent heat. If they are baggy, they’ll let all the heat out and won’t feel right on your body.

So, it may be wise to consult the sizing charts available on Amazon and other online vendors. You could also take a few measurements to ensure you get the right fit.

7. What Is Microfleece?

Microfleece is a lightweight fabric that has highly insulative properties. Base layers feature such a fabric as it’s also compact and highly breathable. aside from adding warmth to your body during winter it also helps to wick sweat away from your body, helps to keep you dry.

8. How Do I Wash and Maintain My Thermals?

All clothing comes with tags that explain how you can wash and care for them. So, don’t feature labels but have these instructions printed somewhere on the garment’s inner side. However, you could hand wash the thermals and drip dry in the shade if you’re in doubt.

As a general rule, you should avoid bleach and other powerful detergents. Such cleaning agents can degrade the anti-microbial, moisture-wicking, and other advantages of having microfibers.


Thermals are a no-brainer if you like to remain active in cold weather. They offer optimal insulation from the biting cold and winds. As you can see, they come in various styles and weight categories, so you can choose what matches your prevailing need.

When shopping, please remember to consult the sizing charts. You could even use a tape measure to get an updated measurement. And, lastly please replace your thermal underwear as soon as the waistband gets loose or if they start getting so sheer that you begin to see through the material.


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