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Thermal underwear goes by many names, from base layers to long underwear, and has more uses than we sometimes think. A good set of thermal underwear is essential for skiing, winter hikes, and camping, but the best base layers can also be used for everyday activities from chilly commutes to walks with the dog to weekend lounging.
Whether you’re headed to the mountain, the cold street, or your couch, read on. Our buying guide below will help you find the best thermal underwear for men, including base layer tops and bottoms.
The Best Thermal Underwear for Men
After testing thermal underwear ourselves, reading other expert reviews, and pouring over user ratings, we’re confident that the 10 base layers below are the best thermal underwear for men. We’ve included options for all types of activities, as well as picks at different price points.
1. Smartwool Classic Thermal Merino Base Layer
Amazon
The outdoorsy community has praised this Smartwool Classic Merino base layer for years. Nothing is new: It’s still one of, if not the very best piece of thermal underwear. The merino wool build is warm without being suffocating — not to mention extremely soft — and durable enough for hiking, skiing, and other high-intensity activities.
2. Uniqlo Heattech
Uniqlo
If you’re looking for a warm base layer to wear in the city or suburbs, we suggest just about anything from Uniqlo’s Heattech line. A cult-favorite line, the Heattech products feature a soft, stretchy fabric that traps heat while controlling moisture and odor at the same time. Plus, the whole collection is very affordable.
3. REI Co-op Midweight Base Layer
REI
Made of a soft, durable synthetic, REI’s midweight base layers offer a ton of performance at a very reasonable price. You’ll also find the base layer in a quarter-zip shirt style, as well as a crewneck, and there are plenty of colors to choose from.
4. Patagonia Capilene Air Base Layer
Backcountry
This base layer from Patagonia has a unique design with a diamond-grid lining to trap heat and a smooth outer that makes it easier to slide your other layers on and off. It’s also very durable, as expected from Patagonia, despite being relatively thin. For odor control, the shirt uses a HeiQ Fresh Tech treatment that works very well.
5. Smartwool Intraknit Thermal Merino Underwear
If you’re looking for a base layer to use for sweaty activities like backcountry skiing, consider the Intraknit line from Smartwool. The layers are all highlighted by a mesh ventilation system to regulate temperature, instead of just making you warmer. Plus, as with the Smartwool layer at the top of this list, the Intraknit line is also made of the brand’s soft, stretchy merino wool.
6. Thermajohn Underwear
Amazon
One of the most highly-rated thermal underwear brands on Amazon is Thermajohn. The synthetic underwear’s fleece lining, four-way stretch, and odor control have earned it 4.6/5 stars on Amazon with almost 50,000 reviews. Plus, you can buy a set with a top and bottoms for less than $30 right now.
7. Fruit of the Loom Waffle Thermal Underwear
Amazon
If you’re looking for something super affordable — or you like the feel of cotton underwear — check out this no-frills thermal underwear from Fruit of the Loom. The waffle knit pieces are cozy and surprisingly warm, and a two-pack costs just $27 on Amazon.
8. Under Armour ColdGear
Under Armour
Another great set of thermal underwear for high-intensity activities — be it skiing or cold-weather football practice — is Under Armour’s ColdGear layers. The pieces feature a dual-layer build to keep moisture under control, as well as strategically placed high-stretch and mesh panels for added range of motion and breathability.
9. Icebreaker BodyfitZone Merino 260 Zone
Icebreaker
These Icebreaker Merino Zone pieces are great if you’re looking for the softness of merino wool and serious performance. They boast flatlock seams for chafe-free movement, a comfortable yet well-fitting design, and a cozy 100% merino build. Users are also especially impressed by the pieces’ durability.
10. Outdoor Research Alpine Onset
Backcountry
Thanks to a fabric made of wool and recycled polyester, Outdoor Research’s Alpine Onset thermal underwear line offers some of the best moisture-wicking powers we’ve seen. This also gives the pieces an excellent balance of stretch and softness, as well as a uniquely lightweight feel.
Thermal Underwear Buying Guide
Although thermal underwear seems like a straightforward garment, there’s a surprising amount of variation between options. Below are a few things to keep in mind while you decide which set (or individual piece) is best for your needs.
Purpose: The best thermal underwear is as versatile as possible, keeping you warm while commuting, sleeping in a tent, and everything in between. However, most base layers lean toward a certain activity — be it lounging, exercising, or everyday wear. Consider how you’ll be using your layers before deciding on a set or piece.
Fabric: Many of the best modern thermal underwear pieces are made of high-quality merino wool, which keeps you warm while reducing sweat and odor. Some base layer fabrics also incorporate polyester to improve stretch, which is great for exercising.
Weight: A base layer’s weight refers to its warmth. A large portion of thermal underwear is ‘midweight’ or 250, as this type of base layer strikes a balance between warmth and slim comfort. For this reason, we’ve mainly stuck with midweight options for our picks.
Features: Keep an eye out for flies, pockets, and vents while shopping for the best thermal underwear. Many wearers prefer minimal bells and whistles for a streamlined fit, while others like the convenience of a fly or pockets. Vents (typically in the armpits of base layer shirts) can help avoid overheating while exercising.
How We Chose the Best Thermal Underwear
To make this list, we tested thermal underwear ourselves and consulted reviews from both experts and real customers. While testing, we made sure to get active to see how the layers dealt with sweat, stink, and movement. We also made sure to do the opposite — relaxing afterward — to see how comfortable the thermal underwear was for lounging. When making our selections, we also sourced from trusted retailers that offer fast shipping (in case that ski trip is right around the corner) and we made sure that every option has at least a 4/5-star rating with a decent amount of reviews.
If you purchase an independently reviewed product or service through a link on our website, Rolling Stone may receive an affiliate commission.
Thermal underwear goes by many names, from base layers to long underwear, and has more uses than we sometimes think. A good set of thermal underwear is essential for skiing, winter hikes, and camping, but the best base layers can also be used for everyday activities from chilly commutes to walks with the dog to weekend lounging.
Whether you’re headed to the mountain, the cold street, or your couch, read on. Our buying guide below will help you find the best thermal underwear for men, including base layer tops and bottoms.
The Best Thermal Underwear for Men
After testing thermal underwear ourselves, reading other expert reviews, and pouring over user ratings, we’re confident that the 10 base layers below are the best thermal underwear for men. We’ve included options for all types of activities, as well as picks at different price points.
1. Smartwool Classic Thermal Merino Base Layer
Amazon
The outdoorsy community has praised this Smartwool Classic Merino base layer for years. Nothing is new: It’s still one of, if not the very best piece of thermal underwear. The merino wool build is warm without being suffocating — not to mention extremely soft — and durable enough for hiking, skiing, and other high-intensity activities.
2. Uniqlo Heattech
Uniqlo
If you’re looking for a warm base layer to wear in the city or suburbs, we suggest just about anything from Uniqlo’s Heattech line. A cult-favorite line, the Heattech products feature a soft, stretchy fabric that traps heat while controlling moisture and odor at the same time. Plus, the whole collection is very affordable.
3. REI Co-op Midweight Base Layer
REI
Made of a soft, durable synthetic, REI’s midweight base layers offer a ton of performance at a very reasonable price. You’ll also find the base layer in a quarter-zip shirt style, as well as a crewneck, and there are plenty of colors to choose from.
4. Patagonia Capilene Air Base Layer
Backcountry
This base layer from Patagonia has a unique design with a diamond-grid lining to trap heat and a smooth outer that makes it easier to slide your other layers on and off. It’s also very durable, as expected from Patagonia, despite being relatively thin. For odor control, the shirt uses a HeiQ Fresh Tech treatment that works very well.
5. Smartwool Intraknit Thermal Merino Underwear
If you’re looking for a base layer to use for sweaty activities like backcountry skiing, consider the Intraknit line from Smartwool. The layers are all highlighted by a mesh ventilation system to regulate temperature, instead of just making you warmer. Plus, as with the Smartwool layer at the top of this list, the Intraknit line is also made of the brand’s soft, stretchy merino wool.
6. Thermajohn Underwear
Amazon
One of the most highly-rated thermal underwear brands on Amazon is Thermajohn. The synthetic underwear’s fleece lining, four-way stretch, and odor control have earned it 4.6/5 stars on Amazon with almost 50,000 reviews. Plus, you can buy a set with a top and bottoms for less than $30 right now.
7. Fruit of the Loom Waffle Thermal Underwear
Amazon
If you’re looking for something super affordable — or you like the feel of cotton underwear — check out this no-frills thermal underwear from Fruit of the Loom. The waffle knit pieces are cozy and surprisingly warm, and a two-pack costs just $27 on Amazon.
8. Under Armour ColdGear
Under Armour
Another great set of thermal underwear for high-intensity activities — be it skiing or cold-weather football practice — is Under Armour’s ColdGear layers. The pieces feature a dual-layer build to keep moisture under control, as well as strategically placed high-stretch and mesh panels for added range of motion and breathability.
9. Icebreaker BodyfitZone Merino 260 Zone
Icebreaker
These Icebreaker Merino Zone pieces are great if you’re looking for the softness of merino wool and serious performance. They boast flatlock seams for chafe-free movement, a comfortable yet well-fitting design, and a cozy 100% merino build. Users are also especially impressed by the pieces’ durability.
10. Outdoor Research Alpine Onset
Backcountry
Thanks to a fabric made of wool and recycled polyester, Outdoor Research’s Alpine Onset thermal underwear line offers some of the best moisture-wicking powers we’ve seen. This also gives the pieces an excellent balance of stretch and softness, as well as a uniquely lightweight feel.
Thermal Underwear Buying Guide
Although thermal underwear seems like a straightforward garment, there’s a surprising amount of variation between options. Below are a few things to keep in mind while you decide which set (or individual piece) is best for your needs.
Purpose: The best thermal underwear is as versatile as possible, keeping you warm while commuting, sleeping in a tent, and everything in between. However, most base layers lean toward a certain activity — be it lounging, exercising, or everyday wear. Consider how you’ll be using your layers before deciding on a set or piece.
Fabric: Many of the best modern thermal underwear pieces are made of high-quality merino wool, which keeps you warm while reducing sweat and odor. Some base layer fabrics also incorporate polyester to improve stretch, which is great for exercising.
Weight: A base layer’s weight refers to its warmth. A large portion of thermal underwear is ‘midweight’ or 250, as this type of base layer strikes a balance between warmth and slim comfort. For this reason, we’ve mainly stuck with midweight options for our picks.
Features: Keep an eye out for flies, pockets, and vents while shopping for the best thermal underwear. Many wearers prefer minimal bells and whistles for a streamlined fit, while others like the convenience of a fly or pockets. Vents (typically in the armpits of base layer shirts) can help avoid overheating while exercising.
How We Chose the Best Thermal Underwear
To make this list, we tested thermal underwear ourselves and consulted reviews from both experts and real customers. While testing, we made sure to get active to see how the layers dealt with sweat, stink, and movement. We also made sure to do the opposite — relaxing afterward — to see how comfortable the thermal underwear was for lounging. When making our selections, we also sourced from trusted retailers that offer fast shipping (in case that ski trip is right around the corner) and we made sure that every option has at least a 4/5-star rating with a decent amount of reviews.