The Best Base Layer for Men for 2023

Use the best base layer and thermal underwear for men to keep your body at the proper temperature during the colder months

Base layers and thermal underwear are worn under other garments, such as a football outfit or regular clothing, to keep you warm during the cooler months. Modern thermal underwear are made to be incredibly light while still doing an excellent job of keeping you warm.

Thermal underwear is made to keep your body temperature up against the cold. However, getting the right underwear might be problematic if you do not know what you need.

Regardless of what kind of outdoor activity you enjoy during the cold season, we have found the perfect piece of underwear for you; from ultra-light base layers to cutting-edge compression thermal underwear.

How We Picked

  • Heat Retention

    We don't all maintain the same core body temperature. Base layer bottoms are adaptable, but warmth is a fluid metric. We considered intended outdoor activities that might spur your purchase of thermal underwear. We made sure that, whatever your reasons were, our picks would do a good job of maintaining your temperature.

  • Material - Comfort and Breathability

    Everyone tends to have similar levels of sensitivity to changes in comfort. But the fit is up to the person since everyone has a different idea of what a good silhouette looks like. Material, seam placement, cut, breathability, and design were all looked at to find ways to make you feel comfortable.

  • Style and Design

    The material, fit, and level of comfort of thermal and base layer underwear make them come in many different styles. We thought about things like the material combination, tag placement, and shape to come up with styles and designs that everyone can agree on and that are also fashionable.

  • Cost-Effectiveness

    After considering all other factors, we made sure to select affordable, quality options. Although some of our picks are expensive, which is expected of thermal underwear and base layers, they are all made with excellent quality.

Our Top Picks

Our Top Pick

Ridge Merino Men's Aspect Midweight Wool Base Layer Shirt

Ridge Merino Men’s Aspect Midweight Wool Base Layer Shirt

This underwear is best for any outdoor activity with a long length that helps it to stay tucked in.

The Aspect Merino Wool Base Layer Crew has a fresh and exclusive design that feels wonderful next to the skin, keeps you warm and dry, and keeps you comfortable all day long. It also has M-Force Technology built in, which makes it the most durable product on the market. This Merino wool shirt is cut long, so it stays tucked in.

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The new inconspicuous thumb loops will hold your sleeves in place.

Our Runner-Up

Men's Classic Thermal Merino Base Layer Bottom

Men’s Classic Thermal Merino Base Layer Bottom

This base layer keeps you cozy all year round thanks to an improved fit and dependable, durable merino wool.

The improved cut and functionality of this Men's Classic Thermal Merino Base Layer Bottom brings you a tight that fits better and performs more effectively. Thanks to the technical benefits of 100% Merino wool, you will be able to play at a high level for a longer time. While you spend the day skiing, running, or hiking, the wool fabric will help keep you warm and comfortable.

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The wide, wool-lined waistband and flatlock seams make itching less of a problem.

Most Cost-Effective

REI Co-op Midweight Base Layer Bottoms - Men's

REI Co-op Midweight Base Layer Bottoms – Men’s

The REI Co-op layer is perfect for performance when the temperature drops.

Base Layer Bottoms include a smooth face, low-bulk seams that make it simple to layer, and a brushed back that increases warmth and comfort. To keep you comfortable, this material dries swiftly and wicks away moisture. Flat seams and a soft elastic waistband get rid of bulk and rubbing, and the 4-way stretch lets you move in a lot of different ways.

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These slim-fitting underwear are made of a stretchy, lightweight polyester weave that allows for a range of motion.

Everything We Recommend

Our Top Pick

Ridge Merino Men's Aspect Midweight Wool Base Layer Shirt

Ridge Merino Men’s Aspect Midweight Wool Base Layer Shirt

This underwear is best for any outdoor activity with a long length that helps it to stay tucked in.

Buy Now

Our Runner-Up

Men's Classic Thermal Merino Base Layer Bottom

Men’s Classic Thermal Merino Base Layer Bottom

This base layer keeps you cozy all year round thanks to an improved fit and dependable, durable merino wool.

Buy Now

Most Cost-Effective

REI Co-op Midweight Base Layer Bottoms - Men's

REI Co-op Midweight Base Layer Bottoms – Men’s

The REI Co-op layer is perfect for performance when the temperature drops.

Buy Now

Who This Is For

Thermal underwear and base layers wick sweat away from the skin and keep the wearer’s internal temperature steady. While it’s far simpler to make the case for a puffy jacket, a baselayer is often just as crucial for outdoor sports like skiing, hiking, and climbing. So, this should be a must-have piece of clothing for anyone who wants to play sports outside in the cold or keep their body temperature stable during the cold season.

Is thermal underwear necessary?
You should always have thermals in your winter wardrobe, no matter how active you are. They’re great for keeping you comfortable and cool, and they’ll keep you from getting all damp and sticky from perspiration thanks to their moisture-wicking properties.

How thick should base layers or thermal underwear be?
As you get active, your body temperature rises, but a layer’s ability to drain sweat away from your body is key to maintaining a comfortable temperature. Thus, warmth is determined not only by the thickness of the material but also by the type of fabric and how well it fits. The materials we tested were all lightweight, but thermal underwear and base layers should also be thick enough to keep the heat in while being light enough to maintain breathability.

Why You Should Trust Us

We find that there are several criteria to consider when evaluating the quality of thermal underwear and base layers; thermal properties, breathability, comfort and fit, and durability. After putting each of these qualities to the test, we ran practical tests by putting them on and seeing how warm and breathable they were, as well as doing other, more specific tests to see how well they fit and how long they would last. When that was completed, we selected our picks based on their quality and cost-effectiveness, with the next best option if you do not like the properties of any.

How We Picked

Range of sizes
The rule of thumb is to purchase thermals that are a size smaller than your regular garments. To an extent, men’s and women’s thermals come in different sizes. Female sizes likewise fall anywhere from 80 to 120 cm, while men have the option of 80 cm, 85 cm, 90 cm, 95 cm, or 100 cm, depending on their height and build. Larger sizes, measuring 110 cm, 105-115 cm, and 110-120 cm, are also available.

Stretchy/elastic
We considered the type of material used to make the thermal underwear and base layers and, during our tests, checked to see how elastic each material was along with how much it could stretch. This was an important factor to consider since thermal underwear and base layers are not the most long-lasting items on the market, and some tend to expand after being washed a few times.

Material
As we’ve established, there are benefits to using either a wool or synthetic base layer since cotton isn’t the finest material to wear when exercising outside in lower temps. Because it can soak up water, it can be very uncomfortable to wear in the winter, especially if it gets stuck next to the skin (or, in the worst case, makes you hypothermic). We tossed out every pair of cotton thermals and focused on wool and synthetic materials.

Comfort
Some thoughtful details in the design can make even the thickest layer seem cozier. One example is the use of flatlock seams. Another example is the use of offset shoulder seams. Several of the best base layers we tested had raglan or offset sleeves so that the seam wouldn’t rub against the wearer’s shoulder when they carried a backpack. Wearing layers that don’t limit your range of motion is also crucial, and you’ll be much more at ease in those that don’t have tags. Finally, we made sure that the material doesn’t give you an itchy feeling.

Breathability
How well a baselayer breathes depends on things like its fabric, thickness, and how to open its weave, among other things. If you’re looking for breathability, lightweight merino wool is your best bet; however, certain high-quality lightweight synthetics come close. So, if you plan to do hard physical activities that will make you sweat a lot, like skiing, cross-country skiing, riding, or climbing, you should probably buy a high-performance base layer.

Lightweight
Lightweight baselayers are the finest for breathability but provide the least warmth. Because of its lightweight and high warmth-to-weight ratio, merino wool is ideal for climate control. The downside to merino is that it loses strength as it gets thinner. It is for this reason that polyester is used for the vast majority of ultralight baselayers.

Thickness
Among the textiles we’ve discussed, merino is the most effective at maintaining body heat. In comparison to polyester, merino has a higher warmth-to-weight ratio and better temperature regulation. The same material that keeps you warm in the winter can also keep you comfortable when you’re sweating bullets in the spring and fall. Silk, like wool, is surprisingly warm for how light it is, but it can’t breathe very well, which is a big problem. Keep in mind that merino doesn’t do much to stop the wind, but some polyester fabrics are so tightly woven that they can resist light gusts, so this is something to think about if you plan on wearing your baselayer as an outer layer.

Style/design
Base layers come in a wide variety of cuts and styles, from tank tops and long and short-sleeve shirts to hoodies, knickers, briefs, and even classic long underwear. Our recommendations center on long-sleeved tops and ankle-length bottoms, as these are the most practical for the winter season and colder temperatures.

Durability
We also considered the material’s durability to make sure that it would last you some seasons. Unlike synthetics, which should last for several seasons, merino is extremely soft but wears out quickly due to the development of tiny holes. We think it’s smart that some brands are combining wool and synthetics to create a stronger baselayer without sacrificing next-to-skin comfort. There isn’t much of a difference in terms of comfort or performance, but the merino/synthetic blends seem to hold up better. When it comes to wearing just a baselayer, though, we always go for the synthetic variety.

Price vs. quality
Worse than being cold the whole time on a camping trip is realizing that the thermals you bought to save money ended up making you colder. Therefore, we made sure that quality came first, after which we were able to narrow down our options to the most cost-effective brands without missing out on the best of thermals.

Our Picks For You

Our Top Pick - Ridge Merino Men’s Aspect Midweight Wool Base Layer Shirt

Our Top Pick

Ridge Merino Men's Aspect Midweight Wool Base Layer Shirt

Ridge Merino Men’s Aspect Midweight Wool Base Layer Shirt

This underwear is best for any outdoor activity with a long length that helps it to stay tucked in.

The Aspect Merino Wool Base Layer Crew has a fresh and exclusive design that feels wonderful next to the skin, keeps you warm and dry, and keeps you comfortable all day long. It also has M-Force Technology built in, which makes it the most durable product on the market. This Merino wool shirt is cut long, so it stays tucked in.

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Who It's For

This is the underwear for you if you're looking for something in the middle. You want it to look nice enough to wear out so that people won't suspect anything, but you also want to be able to use it as a base layer when you go mountain biking, hiking, or skiing.

Why It's Great

The Ridge Men's Midweight Merino Aspect Wool Base Layer Long-Sleeve Shirt is a technical shirt that doesn't seem complex. The designers chose the fabric and the way it was put together to make sure you were as comfortable as possible while doing something outside, like jogging or backpacking.

Potential Flaws

This thermal underwear has some great features. However, it does not have multiple sizes. For that, we recommend the Minus33 Midweight Wool Base Layers.

Other Features

This product is expensive considering the materials used. It does, however, offer a way to pay in four interest-free installments. Shipping and returns are also free.

The neutral tones of the Ridge Merino Aspect make it easy to mix with a wide variety of clothing. If you're putting a sweater on over it, the thumb holes will help it stay in place. But those thumb holes fade into the cuff, so they're not obvious if you don't want them to be, and that's the limit of this shirt's outdoor styling. All of these details soften the shirt's otherwise technical look, making it more versatile.

Merino wool makes up 84% of the blend, while nylon makes up the other 16%. Because it has nylon in it, the Ridge Merino Aspect will last longer than a similar product made of only wool. This is because nylon gives it elasticity and strength.

There is no tag, and the raglan sleeves and shoulder seams are offset. It's easy to move your arms without restriction, and the seam won't rub on your shoulder when you wear a backpack. Your lower back will be protected by the length of the torso (and warm). The shirt is slim without becoming skintight. You can wear it on its own, and it won't add bulk if you layer it with a sweatshirt.

Last but not least, this shirt has a sun protection rating of UPF 50+, which indicates that fewer than 2% of UV rays can penetrate the fabric. Sun protection is doubly vital if you are on snow or water (or at elevation or the equator), as the sun's rays are either reflected and bounced back up at you from the ground or there is less atmosphere to shield you.

Product Specifications

Material: 84% merino wool, 16% nylon
Sizes: S to XXL; fits a 36- to 51-inch chest
Colors: one solid, plus three raglan styles (two solids and one camo)

Our Runner-Up - Men’s Classic Thermal Merino Base Layer Bottom

Our Runner-Up

Men's Classic Thermal Merino Base Layer Bottom

Men’s Classic Thermal Merino Base Layer Bottom

This base layer keeps you cozy all year round thanks to an improved fit and dependable, durable merino wool.

The improved cut and functionality of this Men's Classic Thermal Merino Base Layer Bottom brings you a tight that fits better and performs more effectively. Thanks to the technical benefits of 100% Merino wool, you will be able to play at a high level for a longer time. While you spend the day skiing, running, or hiking, the wool fabric will help keep you warm and comfortable.

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Who It's For

Most of the time, you'll be toting around a heavy backpack, but the weather forecast calls for partly cloudy skies. If the sun decides to make an appearance in the afternoon, the Smartwool Merino Base Layer will still feel great on your skin.

Why It's Great

When the temperature outside drops significantly, we recommend this cozy pair. The 100% Merino wool is cut so thickly (250 g/m2) that this design's unique interlock knit lets it breathe well. This fabric is knitted from merino wool in an interlocking pattern. It has superior odor resistance, breathability, thermal regulation, and comfort. With a flatlock seam structure that reduces rubbing and chafing, a Merino wool-covered elasticized waistband that lies flat on the waist and a classic fly, these pants are as practical as they are comfortable.

Potential Flaws

This pair is expensive for wool and tends to expand between washes. If you want a cheap option, we recommend the REI Co-op Midweight Base Layer Bottoms.

Other Features

Regardless of its price, this brand provides great bonuses with discounts as high as 70% off, along with free shipping for orders above a specific price range, which makes its purchase quite easy. You also get to enjoy bonuses with their membership cards.

Rear gussets now match the front ones, which helps with the fit problems we experienced before. Even though these are made for cold weather, they can be worn in many different situations because they are both warm and let air in.

Product Specifications

Material: 100% Merino wool
Sizes: S to XXL; fits a 30- to 35-inch hip size
Colors: Black, Charcoal Heather, Deep Navy, Laguna Blue Hthr Color Shift, Picante Heather Color Shift, Winter Moss Heather

Most Cost-Effective - REI Co-op Midweight Base Layer Bottoms – Men’s

Most Cost-Effective

REI Co-op Midweight Base Layer Bottoms - Men's

REI Co-op Midweight Base Layer Bottoms – Men’s

The REI Co-op layer is perfect for performance when the temperature drops.

Base Layer Bottoms include a smooth face, low-bulk seams that make it simple to layer, and a brushed back that increases warmth and comfort. To keep you comfortable, this material dries swiftly and wicks away moisture. Flat seams and a soft elastic waistband get rid of bulk and rubbing, and the 4-way stretch lets you move in a lot of different ways.

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Who It's For

Get this if you are uncertain as to whether you will like your first attempt at an outdoor activity. The REI Co-op Lightweight Bottoms are the gold standard for minimalist long underwear, providing you with everything you need to play during the cooler months.

Why It's Great

The polyester and spandex blend used to make the REI Co-op Midweight Base Layer Crew Top and Bottoms are soft and breathable. All-day comfort is guaranteed with these form-fitting pieces.

Potential Flaws

Merino base layers are good if you know what you want to do and don't mind how woolly they feel. The problem is that not everyone goes into a search with a clear idea of what they want. So, if this pair is not for you, feel free to check out our other picks.

Other Features

These underwear continue to set the standard for value in this market because they work well and cost much less than most of the other models in this review. This layer is very breathable and can be worn as a pair of running tights in the fall and winter because it is light and has vents in the right places.

The inseam on this underwear is shorter, but if you're taller than average, REI also sells a longer version. Even though we hoped the fully synthetic construction would be a little more sturdy, it passed our abrasion test and would hold up fine in virtually any practical situation. These affordable men's briefs are perfect for your more athletic winter activities as well as the cool evenings you'll experience while camping towards the end of summer.

Product Specifications

Material: 100% polyester
Sizes: S to XXL; fits a 36- to 53-inch chest
Colors: Four heathered solid colors

Almost Made The Cut - Minus33 Midweight Wool Base Layers

Almost Made The Cut

Minus33 Midweight Wool Base Layers

Minus33 Midweight Wool Base Layers

These men's Merino wool goods are designed for comfort, style, and usability to keep you cozy no matter where you go.

This Men's Merino Wool is versatile enough to be worn all year round, whether layered up or down. The moisture level of your skin can also be controlled by wearing Minus33 Merino Wool since it wicks away perspiration. When this happens, the fabric releases moisture into the air through evaporation, leaving you with a lightweight, odorless material that provides warmth and comfort.

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Who It's For

These are a must-have if you plan on spending time outdoors in wet conditions while wearing a raincoat, snow pants, fishing waders, or any other pair of loose, straight-legged pants.

Why It's Great

Normally, a crew and bottom made entirely of merino would be a durability red flag, but not so with the Minus33 set. This underwear is thicker and therefore more durable than most others because of its weight.

Potential Flaws

These underwear aren't as adaptable as others because they were designed with specific activities in mind, such as hunting, fishing, and layering under snow pants and jackets. They're too bulky to be worn under regular clothes; the pants are too similar to underwear to be worn alone, and the whole set is too heavy for vigorous activities like jogging. If versatility is what you need, you may want to consider our top pick or any of the other options.

Other Features

Our testing showed that the flat-locked seams held up well after being washed and dried three times, and the garments themselves showed no signs of wear or tear after this treatment. These layers are thick, in addition to being soft, and they will last a long time. This makes them ideal for low-intensity activities like sitting on a sled or standing in a river waiting for fish to bite, as they provide comfort and warmth without restricting movement.

Product Specifications

Material: 100% merino wool
Sizes: XS to 6X; fits a 33- to 61-inch chest/24- to 56-inch waist
Colors: eight solids and one camo

Care and Maintenance

Getting the right fit for your thermal underwear
You should make sure that your base layer fits snugly against your skin while still allowing you freedom of movement when trying it on. You should make sure that your base layers are snug, but you shouldn’t go down a size just to do this.

Be careful about overheating
An individual’s base layer, which is the layer next to the skin, should function as a “second skin” at all times. Base layers keep you warm and dry because they add another layer of insulation and pull away sweat. To reiterate, base layers are designed to keep you from becoming chilly, not to keep you warm. If you find that your base layer is increasing your body temperature, you should probably replace it.

How often to clean thermal underwear
Because perspiration is less of a concern in the cooler months, you can extend the life of this garment by not washing it too often. It can be worn for up to five days without being washed because it is designed to get rid of sweat and smell. If they are used for sports, on the other hand, you might want to wash them twice a week.

How to clean thermal underwear without losing the thickness or warmth
The thermals should be washed by hand using a gentle liquid detergent like Ezee or Genteel. With machine washing, the easiest way to care for your thermals so that they don’t shrink is to follow the procedures outlined on the tags or that came with the product. Machine wash on cold or wool wash/delicates setting (if available) at low to medium heat (30 degrees). Check the label to see what kind of temperature range the item is intended for.

How to dry and store thermal underwear
To avoid damage, neither dry cleaning nor bleach should be used on the thermal underwear as the chlorine in many bleaches is toxic to merino wool. Also, avoid wringing out the item because doing so will cause the wool to shrink. Finally, do not force dry the material, as the heat from the dryer or the sun could cause it to shrink. When you’re done wearing, washing, and drying the thermal underwear, you can always fold it away into a closet out of direct sunlight until you need it again.