10 Best Base Layer & Thermal Underwear Tested & Reviewed

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Nothing can stop adventure seekers and fitness enthusiasts from going out and exploring new things and working up a sweat in the great outdoors—not even the winter weather. But this does mean the right gear is crucial to braving the cold: base layers and thermal underwear.

The ideal base layer or thermal underwear should be warm, yet thin and lightweight so that it can be worn underneath clothing. It should also be breathable so that the consumer doesn’t work up too much sweat while moving, and it’s best that is was moisture-wicking properties so that they aren’t wet and catch a chill.

Base layer underwear includes shirts and leggings and should be worn close to the skin to act as a second skin. If winter sports like skiing, snowboarding, or hiking, cycling or running is preferred in the colder weather, stocking up on base layers and thermal underwear is a must.

Last Updated: April 30, 2018
By Richard Haberkost:

We have reviewed your choices and added a nice product. Please continue to revisit as we regularly update and expand the best options for you. Enjoy our section covering reviewing criteria and pick up some good advice in the FAQs section.

Smartwool NTS Mid 250 Zip T
  • Smartwool NTS Mid 250 Zip T
  • 5 out of 5
    Our rating
  • Very comfortable
  • Price: See Here
Duofold Mid-Weight Thermal Pant
  • Duofold Mid-Weight Thermal Pant
  • 4.5 out of 5
    Our rating
  • Quality fabric
  • Price: See Here
Ibex Merino Wool Woolies Crew Shirt
  • Ibex Merino Wool Woolies Crew Shirt
  • 4 out of 5
    Our rating
  • Lightweight
  • Price: See Here

 

10 Best Base Layer And Thermal Underwear

 

Smartwool NTS Mid 250 Zip T

When it comes to keeping warm and staying comfortable, nothing compares to this base layer top. Made from wool, yet stretchy and moveable, this option is comfortable and has stylish slim fit. It is odor resistant, has moisture wicking properties, and is available in multiple colors for both men and women.
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Construction

Made from super warm 100% merino wool (at 250 g/m²) that is knit in Vietnam, the Smartwool 250 Base Layer is hands down one of the best underwear options when it comes to its quality and performance. It is known for feeling so good on the skin, keeping the consumer heated and cozy, with a good rate of warm to weight that makes it perfect from spring to cooler weather. There is no chafing with its flat lock seam and it has a front zipper for ventilation.

Warmth and Breathability

The wool fabric makes this option rank pretty well on the breathable scale, with water vapor being able to pass through the fibers without condensing. And while it performs well on that function, it’s really about its warmth and comfort level that make this a top contender. The merino wool makes this one of the most toasty base layer, and it can also be worn as a mid-layer option.

Style and Fit

The fabric itself is super soft, making it an option that once is worn there is no going back to other brands. The fabric is still flexible enough to move, and it fits to the body well with its slim fit. It is available in multiple colors and is stylish.
Pros
  • Warm, yet light
  • Very comfortable
  • Looks good on and feels even better on
  • Breathable
  • Great quality
Cons
  • Expensive
  • Dries slowly

Duofold Mid-Weight Wicking Thermal Pant

This base layer thermal has a two-ply cotton construction blend that will keep the consumer warm, and a flat lock seams and a moisture wicking waistband. It has rib-knit cuffs and consumer’s 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.
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Construction

Soft and comfortable, Duofold’s thermal underwear pants 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 loosing heat retention.

Warmth and 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.

Style and 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.
Pros
  • Mid-weight and warm when layering
  • Quality fabric
  • Size runs true to fit
  • Very affordable
Cons
  • Not as stretchy
  • Can be loose around the legs

Ibex Merino Wool Woolies Crew Shirt

Available for men and women in various color options, this underwear shirt is among the most well-known (and highly rated) merino base layers. That’s because it is thin, yet warm, making it perfect for winter activities that has the consumer working up a sweat. The merino wool helps to regulate temperature, even when sweaty, fits tight to the body and is stretchy.
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Construction

Made from mostly merino wool at 86 % and nylon, the Ibex Woolies Crew Shirt features 18.5 superfine New Zealand wool yarn that is moveable, yet durable while keeping its shape. The shirt is rib-knit with raglan sleeves, includes flat lock seams to prevent chafing and has a longer cut for more coverage.

Warmth and Breathability

This is an option that performs when it comes to warmth. And it’s the merino wool that takes all the credit here, feeling soft against the skin, while regulating body temperature. It continues to keep warm even when wet. The rib construction helps to allow air to circulate to make it breathable. Overall, this is one comfortable base layer.

Style and Fit

This Ibex base layer is form-fitting, making it great for layering. It has a crew neckline with no tags so it’s not constricting or itchy around the neck. It fits close to the body, is available in black and other color options, and is overall sleek and stylish.
Pros
  • Super soft and warm
  • Lightweight
  • Lifetime manufacture warranty
Cons
  • Pricey
  • Merino wool fabric can be itchy for some

Carhartt Base Force Cotton Super Cold Weather Legging

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.
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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 weighs 9.5 ounces, making them heavy enough to keep the legs warm. The moisture wicking properties help to keep away sweat so that you stays dry. While being nice and toasty, they are still breathable and promote mobility when using as a under layer.

Style and Fit

Available in both black and a neutral color, these leggings are have tight fit without being like compression leggings feel. They have a simple style is that is universal across all types of consumers.
Pros
  • Keep you warm in winter
  • Good quality and thick
  • Affordable price
Cons
  • Runs longer in length
  • Ankle cuffs feel too tight for some

Ekouaer Long Thermal Base Layering Set

This thermal onesie is fleece lined, soft and comfortable, and even though it will keep the consumer warm, it is also breathable so no worries about overheating when on the slopes. With moisture wicking properties and an elastic waist, this set comes in multiple colors. It’s ideal as an underwear option for outdoor sports in the winter like skiing, hiking and more.
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Construction

This thermal underwear top and bottom set is made with 95% cotton and 5% elastane. The long sleeve shirt is midweight and features no tags so it won’t be itching the back of the neck when used as a base layer. The leggings are fleece lined and are equipped with an elastic waist to keep them from sliding down.

Warmth and Breathability

The Long Johns are perfect for winter sports or activities, or can even be worn as pajamas when camping or at home for those chilly nights. This underwear isn’t too thin, or too thick—being a great mid-weight option for layering when its freezing to add extra warmth when outside. There are claims that is is breathable, but this isn’t the best when it comes to ventilation since they are on the thick side. The fabric is moisture wicking, but does take a longer time to dry than other options.

Style and Fit

Hides great under clothes with a snug fit, the Ekouaer base layering set isn’t constricting or bulky. The material is ultra-soft for optimal comfort and of good quality. It comes in multiple color options for both men and women.
Pros
  • Comes as a set of both underwear long sleeve shirt and pants
  • Soft and warm
  • Affordable
Cons
  • Not as breathable
  • Not as stylish as other options
  • Loose around the chest and shoulders

Arcteryx RHO AR Zip Neck

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.
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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 loose 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 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

It’s design makes this one of 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.
Pros
  • Great for layering
  • Durable and comfortable
  • High collar and zip neck
Cons
  • Takes time to dry when really wet
  • Not as breathable as other options

Icebreaker Merino Oasis Long Sleeve Crew

Made from 100% merino wool, this base layer shirt is ideal for outdoor activities, even when it gets warmer (just not hot summer days). It’s breathable, has a slim fit, and odor-resistance and moisture wicking properties. This base layer shirt is known for its comfort when it comes to its softness and overall wear. Versatile for many outdoor activities, this is a to-go for hiking and snow sports.
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Construction

The Icebreaker Oasis is made with 100 % merino wool that translates to 200gm of merino jersey fabric. This makes it soft with its superfine fibers, and gives it anti-odor properties that means the consumer can wear the shirt during a weekend adventure without it stinking. It’s lightweight.

Warmth and Breathability

The merino fabric keeps the consumer warm and regulates the body temperature. It is also very breathable because of its fineness of the fibers.

Style and Fit

This long sleeve is offset on the shoulders to prevent chafing, drop tail hem for added coverage. This is a crew neck cut shirt that is comfortable and non-restricting as a base layer. It comes in many different color options.
Pros
  • Soft and stylish with many color options
  • Resists odor
  • Breathable
  • Versatile and overall good investment
Cons
  • Expensive
  • Runs short in length and sleeves
  • Fabric can be itchy for sensitive skin

DRSKIN Thermal Wintergear Pants

These thermal fleece lined pants are great for activities in the snow and extreme cold weather like skiing and snowboarding. It has a quick fry time, moisture sensing tech, and TWC-Way Air Circulatio to make them retain heat in the winter and be cool in the summer. It has a tight fit and moisture wicking properties.
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Construction

Living up to its name, the DRSKIN Thermal Wintergear leggings are micro fleece lined for optimal warmth. The company uses an odd ramp sewing method so that there is no overlapping of fabrics. It won’t pull on the skin during activity, and has moisture sensing fabric that results in a quick dry time.

Warmth and Breathability

Because these are micro fleeced lined, there is no doubt that these compression base layer pants are warm. Just keep in mind there is no thick fleece material the inside. This underwear retains heat when cold and stays cool in the summer.

Style and Fit

This base layer pant fits tightly to the legs to serve as compression legging, which improve circulation and aid in fast recovery after exercise. These are tight fitting and are overall thin (think base layer), come in various colors and great for training, running, cycling, skiing, triathlons, football, and more.
Pros
  • Very warm
  • Tight and stretchy
  • Affordable
Cons
  • Can run smaller and shorter in size
  • Might be too thin for some

Baleaf Men's Thermal Running 

Base layer or as outer.

Very good for runners and cyclists, breathability is a feature of these pants along with comfort via the soft fleece. When the weather outside is going to be very chilly these pants will protect you and keep you warm.
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Construction

Durable and very comfortable construction, these pants are Spandex at 10% to ensure stretch factor when it is most needed and Polyester at 90% which means durability and breathability.

Warmth/Breathability

The inclusion of a spandex weave ensures stretch and breathability through synthetic polyester, the warmth is held in while allowing some air and moisture to escape due to the fact that synthetic fibers do not retain moisture. For warmth, you get a fleece lining which is protective and comfortable.

Style/FIT

FIT is good due to the stretch capability, the pants shape to your legs, these have designed in reflection to ensure you are seen in gloomy light environments and user-friendly zippers to ensure quick to put on or take off

Cost

Nice price, very affordable and a good investment.

Pros

Protection from cold

Stretch for FIT and flexibility

Breathability

Fleece lining

Reflective clothing tech

Cons

Ensure you choose the correct size for you

Tesla Base Layer Long Sleeve Compression Shirt

With its extreme compression fit, this base layer shirt is designed for free movement and comfort. It has great ventilation and breathability, is quick to dry and comes in many different color options for an affordable price.
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Construction

Made from 87 % polyester and 13 % spandex, the MUD11is an option to be worn for all seasons. Because of its non-abrasion fabric, the shirt has great elasticity and durability. It has an engineered pattern using 3D geometry that is tailored to the body to make it easy to move freely.

Warmth and Breathability

This long sleeve shirt releases heat and wick moisture with a cooling effect. With its quick dry technology, the shirt tires right after washing, or when sweating. The material is breathable even though it is a bit thicker than other options.

Style and Fit

This base layer shirt does run small, so Tesla recommends ordering one size larger than normal. If the consumer does get their regular size, the MUD11 Baselayer Cool Dry Compression shirt will have a snug fit. This shirt is available in 19 different colors and prints.
Pros
  • Keeps cool when hot, warm when dry
  • Quick dry material is moisture wicking
  • Overall good quality, making it great value for price
Cons
  • Runs small (about two sizes smaller)
  • Material is transparent

Helly Hansen HH Dry Stripe Long Sleeve Base Layer

Affordable, yet still a high performance option, this Helly Hansen base layer long sleeve shirt features Lifa stay dry tech that is fast drying with a maximum moisture transfer. The material is non-itch, the shirt is lightweight and has a slim fit. It does a decent job keeping the consumer warm, and has a limited lifetime warranty.
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Construction

Made from non-itch and allergy neutral fabric, this shirt is made from 100% lifa, meaning it is quick to dry, and lightweight—making it perfect for ski trips or backpacking in the mountains. This base layer has flat lock sticking and low bulk cuffs.

Warmth and Breathability

Dry next to the skin, this is a breathable option that will keep the consumer warm and dry without overheating.

Style and Fit

Featuring what the company calls an “iconic” design, this shirt features Helly Hansen’s classic strip along the sleeve. It is as comfortable as it is functional, with an athletic/slim fit.
Pros
  • Great insulation
  • Fits well
  • Stylish
  • Affordable
Cons
  • Can run small for bigger builds
  • Fabric stretches after multiple washes

 

The Criteria We Used For Our Evaluation

It seems obvious that consumers should be looking for a base layer or thermal underwear that keeps the cold away. But how warm the clothing is n’t the only thing that matters when looking for the best item to purchase.

The price range varies among base layers and thermal sets so it’s important that the consumer knows whether or not that they are buying a high-quality option. Sometimes this means investing in a more expensive item, but there are affordable options that still perform well—even though they might have to sacrifice on a few features.

We did all the heavy lifting on the research front so they only finger the consumer has to lift is when they are putting the base layer on. The following criteria we used to find the best base layer and thermals are explained below.

Warmth

First and foremost, the base layer/ thermal should perform well when it comes to keeping the consumer warm. What types of materials are used? Some fabric like merino wool is extremely warm, while spandex options may not cut it in freezing temperatures. How thick is the material? Is it midweight or heavyweight? Is it easy to layer?

Breathability / Ventilation

While being warm is crucial, the last thing anyone wants is to be too hot. This causes sweating, meaning the consumer is wet and can get a chill. How breathable is the fabric? Does it offer ventilation like a zip down in the front to help regulate body temperature?

Durability

How durable is this option? Will it last for more than one winter? Does it easily rip or tear? How easy is it to wash?

Other Important Factors To Consider

All those factors are important, but keep in mind that there are some things a consumer should know when shopping for base layer or thermals.

Materials

Base 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.

Fit

The general rule of thumb is the colder the weather, the tighter the underwear should fit. 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.

Thickness

The thickness of the base 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.

FAQ

Q: What is the best material for a base layer?

A: Merino wool is arguably the best materials because it is super soft and comfort is its main selling point. It is also warm which is important,but is more expensive. Other synthetic fabrics like polyester also works well.

Q: How are base layers supposed to fit?

A: Base layer and thermal underwear is supposed to have a snug fit, as close to the skin as possible to keep the body warm.

 Q: What temperature is this recommended for?

A: While the quality and overall performance varies among thermal underwear and base layers, all the options on this list are ideal to wear during winter and cooler temperatures. Just make sure to wear as a base or mid-layer for optimal warmth.

Q: How thin is this base layer?

A: The thickness of the each option on this list various among products. However, base layers are meant to be thin, yet warm and lightweight.

Q: What does a moisture-wicking base layer mean?

A: A base layer with moisture-wicking properties means that the fabric pulls the moisture from the body to the outside of the shirt or pant where it evaporates more easily instead of being soaked within the fabric.

Q: What is the best base layer for skiing?

A: Skiers should look for a midweight base layer with moisture-wicking for when they work up a sweat.

Sources

  1. Rei, How to Choose Long Underwear (Base Layers), Outdoor Consumer Website,
  2. Polartec, Power Stretch, Fabric Manufactuer Website,
  3. Wes Siler, How To Choose The Perfect Base Layers To Keep You Warm This Winter, News Website, Dec 16, 2014