18 Best Thermal Underwear & Base Layers Tested & Reviewed

The best base layers and thermal underwear are going to keep you toasty and prevent sweat buildup. Fact: thermal base layers are not so well-kept secrets for those that love outdoor adventuring or that work in outdoor construction.

We put a lot of research into what makes a great thermal base layer and laid out some serious thermal underwear options for you. Each piece of the best thermal gear offers all the newest materials and features there are in the most current designs. We made sure to also add this info in our FAQs and Criteria sections.

All this information is there to help you find the best products for your next outdoor excursion. Whether you need some wicking wool or just some simple layers, we are sure what we gathered will accommodate any of your needs.

Standout Picks

Smartwool NTS Mid 250 Zip T
Smartwool NTS Zip T is an affordable option to your thermal underwear arsenal that doesn't skimp on the warmth and cozy option either. The natural moisture-wicking merino wool, polyester and spandex combination will keep you dry and warm without the itch.
Amazon Link
Arcteryx RHO AR
With its trim fit and zip neck design, this underwear top features moisture-wicking fabric with plenty of ventilation. It’s comfortable, warm, durable and layers well. It’s available in multiple colors and even has a chest pocket for storage.
Amazon Link
Under Armour 4.0
The Under Armour 4.0 baselayer leggings are really warm and perfect for cold weather running. They are lightweight, moisture-wicking, and really comfortable--you will barely feel them there while you are running!
Amazon Link
Icebreaker Everyday
This Icebreaker model is perfect for everyday wear, as the name might suggest. It is 100% Merino wool but is more lightweight than most Merino wool options, so you can wear it under hiking gear, running clothes, or your office blues without having to worry about it being too bulky or uncomfortable.
Amazon Link
CW-X Insulator Stabilyx Tights
The CW-X Insulator Stabilyx Tights strengths are twofold, as it will support its wearer both by keeping them at optimum running temperature while providing them with all the stability an athlete will need. The Stabilyx tights are a perfect base layer for the runner in need of the extra support.
Amazon Link
Tesla Compression
Tesla Mesh Compression is a very affordable option for runners who want something with good temperature regulation that isn’t thermal. The compression is a great feature that will help with circulation and muscle recovery, especially if your workouts are a little more diverse.
Amazon Link
Helly Hansen
The right base layer is both high performing and great looking. It fits so well and functions so right that except for the fact that you’re warmer when you need to be and cooler when you should be, you forget you’re even wearing it. Meet the Helly Hansen HG Warm Ice!
Amazon Link
CompressionZ
The CompressionZ Women’s Legging looks great every day for every type of activity. Couple these leggings with cute tops for dinner out, hoodies for evening neighborhood walks or your favorite workout gear when you’re serious about training. No matter how or where you wear these stylish bottoms, you’ll reap endless health and fitness benefits while looking beautiful.
Amazon Link
Duofold Mid-Weight
Duofold Mid-Weight has a two-ply cotton construction blend that will keep the consumer warm, and flatlock seams and a moisture-wicking waistband. It has rib-knit cuffs and consumers won’t have to worry about chaffing with this option. This is among the most popular and highly-ranking base layer bottoms because of its warm, comfort and quality and affordability.
Amazon Link
Paradox Performance Merino
The Paradox Performance base layers and thermal underwear is a super comfortable, fast drying layer that is sure to keep you warm and cozy no matter where your adventures take you. It is an affordable option made with a small amount of merino wool for a soft, moisture-wicking build.
Amazon Link
TSLA Men's Thermal
Looking for a good pair of thermal underwear to add to your wardrobe this winter? Runners need t stay warm and dry but adding too many layers can make it hard to run. That is why the TSLA Men's Thermal leggings are a perfect bottom layer to put on!
Amazon Link
Minus33 Katmai Expedition
Made with 100% merino wool, Minus33 Katmai Expedition bottoms are made to protect and keep warm in the coldest of climates. They are activewear and designed to work with you while you are hiking, running, or participating in your favorite X-treme sport. As an extra layer of cozy skin, you’ll be tempered and comfortable.
Amazon Link
Carhartt Base Force
Made from 100% cotton, these moisture-wicking leggings will keep the lower body warm and dry when sweating out in the cold weather. With its snug fit and elastic waistband, these underwear pants won’t be falling down when running. This option is thick and comfortable, an ideal for braving the cold winter temperatures for outdoor workouts or adventures.
Amazon Link
Columbia Midweight
The Columbia Midweight top is comfortable midweight layer gives just enough thickness without being overly bulky. It will stay put under other layers and it has breathable, stretchy, and moisture wicking abilities that make it very versatile to wear as a base.
Amazon Link
Tasc Performance
A perfect pairing made popular by athletes, Tasc Performance is a top that will contour to the body with a skin with a tight fit. It will alleviate chafing, you won’t even feel like you have it on.
Amazon Link
ColdPruf
ColdPruf is a base layer that will keep you warm and provide essential mobility so that you can engage in outdoor activities without a problem. The technical fibers used have the Silvadur Intelligent system which keeps your pants fresh, odor-free, and reduces harmful and unhealthy bacteria from developing and growing on the fabric.
Amazon Link
Minus33 Kancamagus
Made from 100% Merino Wool, this is a seriously warm baselayer legging for the lower body with a wide range of sizes to help fit most sizes, XS to all the way up to 6 XL. The company has a serious street rep, with over 100 years as a US-based woolen company that provides the best merino wool products to market at the most reasonable prices.
Amazon Link
First Lite Allegheny
First Lite Allegheny fits true to size so whatever your natural body size is would be what you’d want to purchase and then it will layer on nicely beneath your clothing. The use of Merino wool in the fiber mix is a nice compliment which will naturally keep you comfortable in all extreme temperatures, those that are very high and the lowest and coldest.
Amazon Link

Criteria Used for Evaluation

Breathability

Of course, when it comes to running, it’s not only about the running shoes. There are so many other variables to improve your endurance and overall workouts. A base layer is a prime example that can set you apart to become your best.

How warm the clothing isn’t the only thing that matters when looking for the best item to purchase.

There are some factors to consider when you’re looking to buy a new base layer. We don’t only look for the best and new base layers, we also look for the biggest trends and the best reviews. Breathability depends on many factors. It starts with the quality used in the products that allow for the right ventilation and thickness vs lightweight in the material.

A great example of a lightweight breathable material is the Merino Wool fabric. This fabric keeps away bad odors and keeps you warm, that’s why it’s best to use in cold climates. Other fabrics that offer great breathability are synthetic fabrics that offer wicking properties. This means that the base layers don’t really absorb the sweat, rather they transfer it away from your skin. Unlike other fabrics, this is best used in humid and wet climates

Durability

Another important factor that we take into consideration is how durable the base layer will be.

In order to save on cost and keep wearing the same base layer for a long time, we need to take into account the test of time. Merino Wool has been questioned because it is soft and will most likely develop holes with its usage. Therefore, it’s not as durable as the other fabrics.

It’s crucial to read the washing instructions as it will help you extend the gear's lifetime. This will allow you to ensure that the fabric remains intact and durable. Some manufacturers are mixing different fabrics together in order to get one product that is stronger. Of course, there are also some other variables such as how comfortable the product feels on the skin, the technology used and how these products are designed is what keeps them durable without compromising its quality.

Materials

The materials used in these garments is an important feature that must be carefully considered.

Thermal layers are made from various materials, with the most popular being merino, polyester cotton, and even silk. Some may even feature blends of fabric to get the functionality of whatever that specific material has to offer.

Merino wool is the fan favorite material used for base layers. That’s because of how warm, yet breathable its fibers are. It is just as thick as synthetic fabric, yet warmer. But don’t think it will feel itchy like traditional wool. Instead, merino wool is soft on the skin. It is odor-resistant since it has natural antibacterial properties. It is the more expensive of the materials but is so worth it.

Polyester is also a popular material used. It is much less expensive than merino wool, while still being comfortable. It has moisture-wicking functionality and does a decent job of regulating body temperature.

Also affordable, cotton is warmer than polyester and soft. However, its main drawback is that it soaks up a sweat, so isn’t the warmest option for outdoor sports.

This defines the durability, breathability, and comfortability of the gear. The material is most likely what will keep you cool or warm, therefore, be careful and don’t pick your base layer based on a style by compromising the quality of the material. Merino Wool is usually the higher costs because of its ability to be soft and comfortable, it has superior temperature regulation and anti-odor ability, but it’s expensive and less durable than polyester.

Even though it is the most expensive, it is worth the buy. Then we have the blends. Manufacturers mix different materials to acquire the desired quality. Some brands like Arc’teryx and Patagonia provide a mix of materials and provide the comfort of merino wool and the long-lasting trait of polyester.

Fit

Base layers should fit more snuggly--hence the leggings and tighter shirts.

For the best performance, base layers must fit in tightly which will help the material to pull the moisture from your skin. Some people like to use it as an additional layer and that makes the product less functional. Consider getting a base layer that fits in tightly and avoids looking at the style because of looks.

A snug fit prevents air from reaching the skin. It serves as a second skin, so should fit as close to the body as possible without being uncomfortable.

The thickness of the layer will help determine how warm it will be. This is measured by insulation weight, g/m². Lightweight base layers usually fall around the 150g/m², whereas mid-weight thermals are about 250g/m².

Lightweight options are ideal for things like hiking and running where some warmth is needed, but the consumer still wants breathability. Midweight options are better for skiing and are versatile enough to even be worn as a top layer in warmer weather.

Of course, there are even heavier choices, but the consumer should not want to go too heavy to overheat depending on the weather and their activity. Make sure to size accordingly and plan ahead base on how you plan to layer up as well as the weather you are in.

Weight

When measuring the warmth of a base layer, consider its weight.

There are different types of weight – lightweight mid-weight and the heavyweight. Depending on your level of activity and different times of seasons will determine what type of base layer you will need. Lightweight is the best for breathability, for example, however, it does not allow you to stay warm.

If you’re looking to stay warm and use a base layer in colder climates, then you might consider the Merino Wool fabric as it offers a great deal of temperature control. Mid-weight is right in the middle. It has just enough weight for the cold weather and also breathable quality for the hot, summer months.

Be prepared and make sure you have everything covered. You might want to get one of each in order to be prepared.

18 Best Thermal Base Layers

1. Smartwool NTS Mid 250

Where to buy
Amazon Link
Smartwool NTS Mid 250 Zip T
Amazon Link

Smartwool NTS Zip T is an affordable option to your thermal underwear arsenal that doesn't skimp on the warmth and cozy option either. The natural moisture-wicking merino wool, polyester and spandex combination will keep you dry and warm without the itch.

Read more

Material

As we mentioned, SmartWool 250 is made from 84% polyester, 11% Merino wool and 5% Spandex. Each part of the mix offers a different aspect to the soft and warm material.

Polyester breathes and adds durability to the structure of the material while the merino wool’s natural moisture-wicking pulls the sweat away from the skin and keeps you dry without holding in the moisture. The spandex allows the fabric to hug the skin and gives it just enough elasticity to not chafe while moving with the body. It sits well under other garments and doesn't slide around.

Breathability

That small percentage of merino wool adds a large amount of breathability to the Smartwool NTS Zip T material. Merino wool helps temper the body while you are warming up or cooling down. It uses the vapors to help keep your temperature consistent while using the air to dry so you don’t get any sweat build up from activity.

A great addition to the breathability factor is the front zipper that hits midway through the chest. If you find yourself getting too warm and don’t want the neck up, just un-zip and you have more heat release, making a more arid fit.

Fit

Offering this shirt in women and men’s sizes give options to body styles and fit preferences. SmartWool NTS is a long sleeve, athletic fit, T-shirt design that hugs the body, which is due to the added spandex. It does not restrict but sits nicely under other clothing without chafing or discomfort.

As an added layer of skin, you won’t be bothered by friction. The Polyester gives the thickness to the material and keeps it durable as well. This gives a softness to the fit of the shirt that 100% wool sometimes doesn’t offer.

Value

You're going to pay a little more for this one but you are getting you're getting more. It offers so much warmth and comfort and fits like a body glove.

You won’t have to stress about putting it through some activity either. Smartwool NTS Zip T is blended for versatility and durability. Each thread works together to stay together while keeping you warm.

Amazon Link

2. Arcteryx RHO AR

Where to buy
Amazon Link
Arcteryx RHO AR
Amazon Link

With its trim fit and zip neck design, this underwear top features moisture-wicking fabric with plenty of ventilation. It’s comfortable, warm, durable and layers well. It’s available in multiple colors and even has a chest pocket for storage.

Read more

Construction

Made from 90% polyester and 10% elastane, this base layer features Polartec Power Stretch. This means the material can stretch with movement, yet resilient enough not to lose its shape. This high-performance fabric wicks moisture, and it also features a flatlock construction that improves next-to-skin comfort.

Warmth and Breathability

Because of its Polartec Power Stretch material, this zip neck shirt is supposed to be breathable but is lacking when compared to other Arc'teryx base layers. It does do a decent job when it comes to moisture management, but also not as well as the previous options on this list. While the zip neck adds to its ventilation, its tall collar helps to ward off the weather elements like the wind. The mid-weight fabric is heavy (at 10 oz.) and warm, and its trim fit further aids to its thermal efficiency.

Style and Fit

Its design makes this one of the most stylish options on this list. It has a single laminated chest pocket for holding personal items like money when going for a long run or hike. It has a trim fit that is next-to-the-body without being constricting and is perfect for layering. Its high-performance weather protection makes it versatile across various outdoor activities.

Amazon Link

3. Under Armour 4.0

Where to buy
Amazon Link
Under Armour 4.0
Amazon Link

The Under Armour 4.0 baselayer leggings are really warm and perfect for cold weather running. They are lightweight, moisture-wicking, and really comfortable--you will barely feel them there while you are running!

Read more

Breathability

These are moisture-wicking and dry quickly--and their odor prevention tech will ensure your tights stay smelling fresh.

Durability

These are really expensive but they are perfect for those of you who need something that will keep you warm during all of your runs. They are durable and, while they don't have any reflective features, they are the perfect base layer for you serious runners out there.

Fit

Their quick-dry construction will help keep you cool and dry and their 4-way stretch ensures full range of motion.

Weight

No matter how much you layer, you will find that this base layer is really lightweight and won't retain sweat, so they won't get soaked and weigh you down.

Materials

These leggings are made of 100% polyester and their thermal grid fabric will keep you warm.

Amazon Link

4. Icebreaker Everyday

Where to buy
Amazon Link
Icebreaker Everyday
Amazon Link

This Icebreaker model is perfect for everyday wear, as the name might suggest. It is 100% Merino wool but is more lightweight than most Merino wool options, so you can wear it under hiking gear, running clothes, or your office blues without having to worry about it being too bulky or uncomfortable.

Read more

Breathability

The fantastic Merino wool content of this base layer means that you’ll stay warm without overheating or dealing with excess sweat. Merino wool naturally wicks moisture and is ultra-breathable, as well as odor-resistant.

Compared to other base layers made with Merino wool, this one is very thin and lightweight, so you can wear it under practically anything or as a sheer top over a camisole or sports bra. It’s the perfect layer for if you just need a little bit more warmth and coverage without needing a heavy-duty undershirt.

Durability

If you can afford to invest in this base layer, you will find that it is worth every penny. Not only is it lightweight and effective, but it is also incredibly durable. The materials it uses and the construction ensures that it is reinforced in all of the right areas.

Fit

When it comes to fit, this base layer fits snuggly and tightly. It is easy to layer this one because it is not bulky. Since it is so lightweight and thin, this is the perfect base layer for those of you who get cold and need to add more.

Weight

As far as the weight of this base layer, this one is incredibly lightweight. Since it has moisture-wicking properties, you will also find that this base layer won't weigh you down if you sweat a little or get wet.
Materials

Made with 100% Merino wool, it is soft and comfortable as well as non-itch. The neckline is accommodating to whatever you may want to wear over the layer and will allow room to move and breathe if you’re active. The fit is slim so it isn’t bulky or hard to wear underneath other tops, but it also runs a bit small and short.

Also, the material isn’t blended with any spandex or Lycra so it doesn’t have a lot of stretch and may easily lose its shape if stretched out.

Amazon Link

5. CW-X Insulator Stabilyx Tights

Where to buy
Amazon Link
CW-X Insulator Stabilyx Tights
Amazon Link

The CW-X Insulator Stabilyx Tights strengths are twofold, as it will support its wearer both by keeping them at optimum running temperature while providing them with all the stability an athlete will need. The Stabilyx tights are a perfect base layer for the runner in need of the extra support.

Read more

Breathability

The Stabilyx tights are much more known for keeping in their heat over their warm weather wear. They are also remarked on having remarkable compression, preventing muscle pain and fatigue after extended activity.

Another attribute of note is these leggings provide knee support and stability, so issues with injury, recovery, or problems with chronic leg conditions can be mitigated by the CW-Xs support web. The Stabilyx also sports a support panel to help with abdominal and lower back support.

Durability

These are on very high end as far as prices go for tights, but they deliver on their price in both product quality and performance. If you are looking for a year-round base layer, the CW-X Insulator Stabilyx Tights may not be a perfect fit, as they tend to keep a runner pretty warm.

They are a remarkable pair of tights in that the support and compression they provide makes them very valuable to the runner who needs that specific type of gear: If they fit your niche, they are well worth the cost.

Fit

These running tights are made seamlessly to optimized wearer comfort and prevent and abrasiveness and discomfort that the repetitive motion can cause. Now the one negative with the Stabilyx Tights that a lot of wearers warned about is that they can sometimes be very difficult to put on.

Weight

When we took a look at the overall weight of this base layer, we found that despite how much warmth they provide they are still really lightweight. If you need to travel you will find that these pack light and when you run or workout in them you will find that they are great at wicking away moisture.

Materials

The general consensus is that once they are on, though, they perform more than satisfactorily. The CW-X Insulator Stabilyx Tights are made from 80% Coolmax and 20% lycra.

Amazon Link

6. Tesla Compression

Where to buy
Amazon Link
Tesla Compression
Amazon Link

Tesla Mesh Compression is a very affordable option for runners who want something with good temperature regulation that isn’t thermal. The compression is a great feature that will help with circulation and muscle recovery, especially if your workouts are a little more diverse.

Read more

Breathability

The material blend is great for wicking moisture away and there are mesh panels for ventilation in the back and sides, keeping you cool and dry. It does offer a little more warmth when layered with other gear, but it’s a better choice for temperature regulation while running in any season than to keep warm while doing things like hiking and skiing. It also will help keep you protected from UV rays with UPF 50+.

Durability

This base layer is made of high-quality material that many other base layers use as well. It is really durable and built to last--so you can keep it around for many seasons to come.

Fit

Customers expressed dissatisfaction with the fit and not often did they all have the same complaint. Some said it was too long while others said the sleeves were too short, some expressed it didn’t have enough compression and others complained it was too tight to wear. The issues are inconsistent and wide-spread, but this inconsistency may mean that they are outliers for an otherwise useful product that many others loved.

Weight

It does offer a little more warmth when layered with other gear, but it’s a better choice for temperature regulation while running in any season than to keep warm while doing things like hiking and skiing. It also will help keep you protected from UV rays with UPF 50+.

Materials

The material make-up is 87% polyester and 13% spandex for a great combination of elasticity and function. The fit is unfortunately where this base layer falls short.

Amazon Link

7. Helly Hansen

Where to buy
Amazon Link
Helly Hansen
Amazon Link

The right base layer is both high performing and great looking. It fits so well and functions so right that except for the fact that you’re warmer when you need to be and cooler when you should be, you forget you’re even wearing it. Meet the Helly Hansen HG Warm Ice!

Read more

Breathability

The lean design and low bulk cuffs make throwing your layers over easy-breezy. Flatlock stitching adds essential smoothness with anti-chafing and less irritation. With warm wool and wicking properties together, you’ve found your perfect long sleeve base layer!

Durability

This is the solution for you, functions are wide and regulate temperature at any given time provides insulation and drying capabilities while simultaneously forgetting you’re wearing it at all.mmIf you are an all-weather runner we have what you are looking for, one that can keep you warm when need be and can also help you cool down when there is need to due to its thermoregulatory function.

Fit

This wool base layer is available in 18 colors and dual tones, each as sleek as the next - Black with Flag Red and Racer Blue with Evening Blue are exceptional. Sophisticated technologies contrasted with a classic design fuse to create a high functioning, aesthetically pleasing base layer.

Flatlock stitching and low-bulk cuffs mean comfortable fabrics and fit next to the skin. You need your base layer to work for you and look great, while simultaneously forgetting you're wearing it at all. With the NH Warm Ice, mission accomplished!

Weight

The best part about this base layer is that it is really lightweight! Since it doesn't absorb sweat, you won't have to worry about it weighing you down either.

Materials

Coupling merino wool with 43% polypropylene makes for an excellent fabric that thermoregulates and feels right next to the skin while also providing both insulation and drying capacities. Patented Lifa T3 hollow fiber engineering keeps athletes even warmer during hardcore workouts in the coldest climates.

Amazon Link

8. CompressionZ

Where to buy
Amazon Link
CompressionZ
Amazon Link

The CompressionZ Women’s Legging looks great every day for every type of activity. Couple these leggings with cute tops for dinner out, hoodies for evening neighborhood walks or your favorite workout gear when you’re serious about training. No matter how or where you wear these stylish bottoms, you’ll reap endless health and fitness benefits while looking beautiful.

Read more

Breathability

The patented Smart Moisture Management system eliminates moisture and sweat and protects the body from chafing and abrasions or irritation. We love the antibacterial/anti-odor technology fused into the fabric.

Durability

When you don’t have time to shower between the gym and lunch, you don’t have to worry - between the microbial protective system and the wicking fabric, you’ll feel fresh and ready for anything.

Fit

We love the on-trend appearance of these sleek compression leggings. They fit snug in all the right places, offering excellent support and an attractive fit. With go-to, all-occasion capability, the CompressionZ Leggings are certain to be a favorite. Reasonably priced, we’re pretty sure you’ll want one in each color (nine, to be exact)!

Choose Leopard Blue to appease your wild side or sophisticated Ferns Silver for day outings that transition into a night at the gym. With odor free fabric, not only are they the perfect “everything” pant, you’ll love the way you can wear them from gym to park-and-play to dinner without missing a beat!

Weight

Average priced, but this pant does its duty as your go-to fashion legging and compression gear. Well worth it! The pants stand on their own hence eliminating the need to buy other compression clothing. Quite amazing as it provides just the boost that your lower half needs and craves for.

We have to admit that not everyone likes to put on shorts, reasons best known by them that is why we feel that this compression pants will be your go to. They act as support on your lower half eliminating the need to shop for a number of compression clothing, they are a perfect choice since they also have a number of advantages with them.

Materials

Sit back and relax - this may take awhile. The CompressionZ Legging helps to reduce unwanted muscle motion during runs or hard workouts. This assists in energy waste-reduction, ultimately improving your workout and stamina. The compression fabric also works to improve circulation and reduce muscle fatigue and pain during and after your training.

This helps athletes to feel less soreness even days after strenuous workouts, too. The patented Smart Moisture Management system eliminates moisture and sweat and protects the body from chafing and abrasions or irritation.

Amazon Link

9. Duofold Mid-Weight

Where to buy
Amazon Link
Duofold Mid-Weight
Amazon Link

Duofold Mid-Weight has a two-ply cotton construction blend that will keep the consumer warm, and flatlock seams and a moisture-wicking waistband. It has rib-knit cuffs and consumers won’t have to worry about chaffing with this option. This is among the most popular and highly-ranking base layer bottoms because of its warm, comfort and quality and affordability.

Read more

Material

Soft and comfortable, Duofold’s base layers and thermal underwear are 60% cotton and 40% polyester. It has flatlock seams for no chafing and moisture management tech that wicks away moisture to keep the skin dry without losing heat retention.

Breathability

Since it has two layers of fabric blended together, consumers can rely on these thermal pants keeping them toasty. This is a mid-weight pant, ideal for layering under jeans for outdoor work hiking or camping, under jogging pants for running or other workouts.

Fit

This thermal pant has a close-to-body fit that is slim and has a convenient front fly. It comes in a few color options including black and winter white.

Amazon Link

10. Paradox Performance Merino

Where to buy
Amazon Link
Paradox Performance Merino
Amazon Link

The Paradox Performance base layers and thermal underwear is a super comfortable, fast drying layer that is sure to keep you warm and cozy no matter where your adventures take you. It is an affordable option made with a small amount of merino wool for a soft, moisture-wicking build.

Read more

Construction

The fabric of this shirt is made up of 84% polyester and 11% merino wool to wick moisture and leave you feeling dry and comfortable. The blend also contains 5% spandex, so it will have a decent stretch while retaining its shape and providing a close fit.

Warmth and Breathability

Although the amount of merino wool is small, it is helpful in keeping you warm while still being breathable without having to be too thin. It will help you stay warm when you are cold and keep you nice and cool when you are warming up.

Style and Fit

The cut of this shirt is athletic so you have a close fit and good mobility without sacrificing warmth or comfort. The sleeves have thumb holes which are great for keeping your base layer in place and providing a little extra coverage over your hands and wrists. The zipper design also allows for a little wiggle room and ventilation.

Amazon Link

11. Tesla Thermal

Where to buy
Amazon Link
TSLA Men's Thermal
Amazon Link

Looking for a good pair of thermal underwear to add to your wardrobe this winter? Runners need t stay warm and dry but adding too many layers can make it hard to run. That is why the TSLA Men's Thermal leggings are a perfect bottom layer to put on!

Read more

Use

These thermals are made to be used by runners and other active individuals who need an added layer of protection from the cold but who do not want to be impeded by bulky layers. The TSLA Men's base layers and thermal underwear are great for cold weather protection.

Weather Resistance

The design of these thermal leggings is such that it easily traps body heat where it belongs while still allowing full range of movement in the legs and torso. It will protect you against the cold chill of winter weather!

Materials

These pants are made from 90% Polyester and 10% Polyurethane. Excellent elasticity with an enhanced range of motion is the key to their popularity among runners and athletes of all skill levels. The material is soft and comfortable and hugs you tightly for compression control that makes your runs more enjoyable.

Fit

The TSLA Men's Thermals do tend to run a little small so it is advised to buy one size up to ensure a good fit. They are designed to be compression legging so you can expect a snug fit so if this is not what you are looking for then this might not be the ideal choice for you.

Bottom Line

The bottom line is the TSLA Men's Thermal base layers and thermal underwear is a good choice for runners looking for a good underlayer to add to their winter running wardrobe.

Amazon Link

12. Minus33 Katmai Expedition

Where to buy
Amazon Link
Minus33 Katmai Expedition
Minus33 Katmai Expedition
Minus33 Katmai Expedition
Amazon Link

Made with 100% merino wool, Minus33 Katmai Expedition bottoms are made to protect and keep warm in the coldest of climates. They are activewear and designed to work with you while you are hiking, running, or participating in your favorite X-treme sport. As an extra layer of cozy skin, you’ll be tempered and comfortable.

Read more

Material

400g of 100% merino wool is what Minus33 is offering in the Katmai Expedition. This ultra sweat-wicking material is machine and drier proof, making it easy to care for as well. It is extra soft and made to work in some of the most extreme temperatures.

Merino wool is known for keeping the body tempered and sweat-free no matter what you are doing. However, the material isn’t light and is made fo getting in extreme activity in extreme environment. This is the reason they are called Expedition, they are Minus33’s expedition weight bottoms.

To add to the soft, sweat-wicking, durable merino wool, these offer 50+ SPF rating. When your out, you get sun and it helps when you don’t have to worry about a burn while your clothed. You never know what elements you’ll find yourself in when you’re having fun.

The KatamaiExpedition is also sewn with flat seems and doesn't have any togs to cause irritation. You’ll also enjoy the convenience of the stretchy ribbed cuffs. These ensure you're not bunching up and can out that top layer on without any interference.

Breathability

Retaining heat is the name of the game and Minus33 does that while still allowing room for air. This teamed up with the wicking properties create a consistent layer or warmth.

Furthermore, their slight compression design helps blood flow. Good circulation keeps you warmer as well. The colder you are the slower your blood flows, just another reason why good circulation is important. It also helps prevent cramping and other running and high activity ailments.

Fit

With a large range of sizes in both men and women's models, you get a large selection to get the most customized fit possible. We also mentioned the ribbed cuffs, which offer a secure fit around ankles.

You’ll also know the fit is right in these when they fit you snug without restriction. Thermal underwear should hug, warm and feel good against the body and the Katmai Expedition does all of this well.

Value

Worth the money is what consumers are saying. We like that kind of feedback and from what we have gathered, those words can’t be truer. Whether you're hunting, skiing or working out in the elements, Minus33 is offering you a soft warmth made of 100%softened merino wool. You won’t want to take them off,

Amazon Link

13. Carhartt Base Force

Where to buy
Amazon Link
Carhartt Base Force
Amazon Link

Made from 100% cotton, these moisture-wicking leggings will keep the lower body warm and dry when sweating out in the cold weather. With its snug fit and elastic waistband, these underwear pants won’t be falling down when running. This option is thick and comfortable, an ideal for braving the cold winter temperatures for outdoor workouts or adventures.

Read more

Construction

The material of this base layer pants is 100 % cotton ring-spun knit reinforced stitching. It includes rib-knit cuffs to keep the warmth in, and a tagless label to ward off neck irritation when layering. It also features stain breaker technology to help to get rid of stains when washing.

Warmth and Breathability

The Carhartt underwear pants weigh 9.5 ounces, making them heavy enough to keep the legs warm. The moisture wicking properties help to keep away sweat so that you stay dry. While being nice and toasty, they are still breathable and promote mobility when using as an underlayer.

Style and Fit

Available in both black and a neutral color, these leggings have tight fit without being like compression leggings feel. They have a simple style is that is universal across all types of consumers.

Amazon Link

14. Columbia Midweight

Where to buy
Amazon Link
Columbia Midweight
Amazon Link

The Columbia Midweight top is comfortable midweight layer gives just enough thickness without being overly bulky. It will stay put under other layers and it has breathable, stretchy, and moisture wicking abilities that make it very versatile to wear as a base.

Read more

Materials

Omni-HEat thermal reflective lining incorporated into the fabric increases overall warmth you can retain throughout the body. It is a versatile product that works very well on its own or as a layer underneath other clothing. The fabric is treated with anti-odor technology to keep you fresh.

Weight

This is a great product of the most active people who enjoy exercising outdoors in all weather, even extreme cold. Runners, hikers, rock climbers, and the avid skier can gain a lot of heat with the heat entrapment technology this top provides.

Fit

You will spend a couple of bucks on this top but it has an incredible ability to retain heat, which is what you want on chilly days. It can work well for an average workout as well as benefit you on the slopes. It is a great piece of clothing to have in your closet that you can use whenever you will be in cooler temperatures.

Amazon Link

15. Tasc Performance

Where to buy
Amazon Link
Tasc Performance
Amazon Link

A perfect pairing made popular by athletes, Tasc Performance is a top that will contour to the body with a skin with a tight fit. It will alleviate chafing, you won’t even feel like you have it on.

Read more

Materials

The coldest days to the best with layers, and having a layer that will lay on the skin without sliding or bunching up and one that won’t add extra bulk makes it a great product that will work with almost any top clothing. The breathability will help your skin stay dry and also keep in the warmth close to your skin.

Weight

This shirt is light but still makes an ideal under layer for those cold days

Fit

This top fits like a second skin so it will easily fit as a base layer under pretty much any type of clothing. Even though it provides a close fit it doesn’t feel restrictive at all. It also has plenty of stretches so you will have no problem with the range of motion or movement. This is a very soft to that has excellent moisture wicking abilities.

Amazon Link

16. ColdPruf

Where to buy
Amazon Link
ColdPruf
Amazon Link

ColdPruf is a base layer that will keep you warm and provide essential mobility so that you can engage in outdoor activities without a problem. The technical fibers used have the Silvadur Intelligent system which keeps your pants fresh, odor-free, and reduces harmful and unhealthy bacteria from developing and growing on the fabric.

Read more

Materials

The cotton two-layer engineering is really something. It is set up to trap your natural body heat between the layers. You effectively act as your own furnace. This allows the outer portion of the pant to shield from the cold while the inner portion is circulating warm air. The polyester textile will do it’s magic keeping the pant very strong, almost tear resistant, and will help it hold its shape as it isn’t a fabric that is prone to shrinkage.

Weight

The tagless labeling is a thoughtful feature that will allow this product to sit well on your body without any annoying itching or irritation from a flapping piece of fabric

Fit

The front and back rise gives a great amount of coverage and very smooth wearing when you are engaged in outdoor activity. The front fly is another practical feature.

Amazon Link

17. Minus33 Kancamagus

Where to buy
Amazon Link
Minus33 Kancamagus
Amazon Link

Made from 100% Merino Wool, this is a seriously warm baselayer legging for the lower body with a wide range of sizes to help fit most sizes, XS to all the way up to 6 XL. The company has a serious street rep, with over 100 years as a US-based woolen company that provides the best merino wool products to market at the most reasonable prices.

Read more

Materials

This product is naturally perfect. Merino wool is breathability and can help with moisture management, it is a four-season fiber as it can keep you incredibly warm while also maintain your coolness, it is odor resistant as well as strong, and this is all in its natural makeup. It is amazingly soft as well, beating out the cliche of itchiness when one thinks of the feel of wool.

Weight

this baselayer offers such tremendous functionality as mentioned above due to this special, natural material, it also offers a rating of UPF 50+ so that it can protect your skin from intense sun rays, especially those that are magnified by reflecting off of crystalline white snow.

Fit

Literally, there aren’t any sizes that are not covered by this brand. The smallest XS to the largest 6XL can go out with protection. When you need to wash your product, this one will be cleaned with ease. It is safe to use in the machine to wash and it will dry well. This is a product that can be used in three seasons, making it very useful for a wide variety of outdoor activities that require a solid base layer.

Amazon Link

18. First Lite Allegheny

Where to buy
Amazon Link
First Lite Allegheny
Amazon Link

First Lite Allegheny fits true to size so whatever your natural body size is would be what you’d want to purchase and then it will layer on nicely beneath your clothing. The use of Merino wool in the fiber mix is a nice compliment which will naturally keep you comfortable in all extreme temperatures, those that are very high and the lowest and coldest.

Read more

Materials

A very important feature about this product especially for those that are going out in the wilderness for some time and need to pack light, pack smart, and not have access to amenities for some time, these are going to serve you well. They can actually last for a couple of days on without developing a build-up of odor making yourself a bit too ‘ripe’ for others or yourself

Weight

In addition, if you find yourself sweating, these won’t keep that moisture in making your skin clammy, they will wick it away and dry quickly so you can maintain a comfortable feel and dryness that will aid in containing essential warmth.

Fit

This Is a product that will move with you, handle the elements, and legit keep you set with temperature regulation and comfort for days should you need to use them on a long term basis like that. This makes these an ideal pair for hunters or especially for through hikers that go on long hikes with stops for quick camps where packing light and effectively is most essential.

Amazon Link

Join our private, growing community of passionate runners

Inside RunnerClick Pro, runners of all strengths come together to meet and support one another, get answers to burning questions, learn from experts, participate in personal challenges, and more.

Join our private, growing community of passionate runners

Inside RunnerClick Pro, runners of all strengths come together to meet and support one another, get answers to burning questions, learn from experts, participate in personal challenges, and more.