Whatever You Call Thermal Underwear—Long Johns, Skivvies, Thermal Tights—These Are the Best for Men

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Long johns, base layers, skivvies—there are many names for thermal underwear for men. But the main purpose of these cozy tights is the same no matter what you call them: they retain heat and wick sweat away from your skin, keeping you dry and warm.

Classic thermal styles only employ cotton knitted into a waffle pattern for warmth, but materials like wool, nylon, and polyester have become popular options because of their durability and insulating properties. Some pairs of thermal underwear for men are suitable for cold-weather activities like snow-shoeing or riding a fat-tire bike; others prioritize comfort for lounging après ski; and a select few do both.

The Best Thermal Underwear for Men

• Best Overall: Smartwool Merino 150 Thermal Underwear

• Best Budget Option: Carhartt Force Midweight Thermal Underwear
  

• Best Wool Option: Minus33 Merino Wool Underwear
  

• Best for Lounging: Mack Weldon Warmknit Long Thermal Underwear
  

• Most Versatile: Duluth Trading Co. Buck Naked Performance Thermal Underwear
  

What to Consider

Output

In some product descriptions for thermal underwear, the brand will list the garment’s suitability for high output or mixed output. Output refers to your activity level.

If you want something that’ll keep you dry while you’re working up a sweat cross-country skiing, opt for a lightweight, high-output pair. A thin profile can help the long johns move moisture away from your skin more quickly instead of a thick pair that’ll get weighed down when it gets damp.

Say you prefer to bundle up while you lounge by the fire with a book and a cup of tea, or you need something warm to sleep in during the winter—a thick pair made for low or mixed output will do the trick.

Fit

The fit of thermal underwear for men is similar to that of a pair of boxer-briefs. They should hug your body without inhibiting your mobility, fitting snugly enough that they don’t bunch up under your snow pants or jeans.

Long johns meant for high-output activity are referred to as slim and generally fit similarly to compression activewear. If you want thermal underwear for daily use in winter, opt for a pair described as having a regular fit.

Materials

The fabric used in thermal underwear for men ranges from the traditional option, cotton, to materials like merino wool, synthetics, and blends of several types.

Cotton and Modal

Avoid pure cotton for strenuous activity because it’s quick to absorb sweat and gets weighed down with moisture. Since the moisture is close to your body, you’ll get cold fast if your long johns get wet and stay wet. Instead, opt for a cotton-polyester blend, or a synthetic pair.

Modal is a similar material made from Beech trees. It’s considered a more sustainable option than cotton, but has many of the same benefits and drawbacks—it’s breathable and moisture-wicking, but struggles to dry out quickly once it does get wet.

Synthetics

Cotton blends and synthetic materials like polyester give you the comfort and moisture-wicking properties you need to stay dry during high-output activities like skiing, snowboarding, or running. Synthetics retain heat even when they get wet, wicking sweat away from the body so you stay warm and dry. Thermolite is a popular synthetic blend common in long johns because it’s insulating and moisture-wicking.

Just know synthetic fabrics can get smelly, and that odor might be hard to get out. Our colleagues at Runner’s World have some tips for getting that eternal stink out of synthetic fabrics. Spoiler: Drying them out as soon as you get inside is a must.

Thermal underwear for men that uses mostly polyester usually requires less work to maintain the original shape after laundering it, whereas merino wool stretches out if you don’t dry it flat and cotton shrinks if you put it in the dryer. That said, some people find polyester to be scratchy against the skin—if you typically have this issue with synthetic materials, opt for a blend.

Wool

Though it’s the most expensive, merino wool is considered the best base layer for its natural properties such as odor control, heat retention, and the ability to wick moisture. Merino wool and wool blends are best suited to high-output activity. Merino isn’t scratchy like virgin wool, though some people may want something even softer. Wool blends often employ cotton or synthetics for a softer feel.

Fabric Texture

The texture of the fabric can also play a part in heat retention. For instance, brushed fabric has raised fibers for a soft texture that feels like a pair of fleece sweatpants.

How We Selected

We judged these pairs of thermal underwear for men based on their warmth, comfort, and durability. We examined the materials, noting the fabrics’ insulating and moisture-wicking properties. We read through customer reviews to determine which pairs are the most comfortable to wear and how well they retain their fit and shape after multiple wears and washes. We also recommend thermal underwear we have worn personally while running and cycling in winter.

Merino 150 Thermal Underwear for Men

This mid-weight thermal underwear uses merino wool with a bit of nylon for shape retention and durability. It’s odor-resistant and moisture-wicking so you can use it for both high-output activity as well as lounging.

It has a flat-seam construction to prevent chafing, and the wide waistband resists creasing and stays in place. The slim fit doesn’t restrict as much as a pair of compression shorts. While the weight is versatile enough for mild cold, you’ll want something heavier if you’re in temps well below freezing.

Force Midweight Thermal Underwear for Men

Carhartt makes its men’s thermals the same way it does its storied outerwear: to be simple and durable. The classic waffle-knit traps heat while the cotton-polyester blend wicks away moisture. The fabric also has impressive odor control according to customer reviews, which attest this pair won’t stink up after long days of work or play.

Customers also say these thermals perform better than the price may suggest. You can expect minimal shrinkage in the wash and in the dryer. These aren’t bulky, but will help keep you comfortably warm when the temperature dips well below 20 degrees, according to one reviewer.

Buck Naked Performance Thermal Underwear for Men

Duluth’s base layer pants are great for those who want a more customized fit because the brand offers them in different inseam lengths: 30 inches and 32 inches. Choosing the proper length can eliminate any unwanted bunching at the ankles.

The ankle cuffs keep them in place and make it easier to layer socks over top. The waistband holds up after several washes and doesn’t lose elasticity or get wavy (i.e., stretched out) after multiple uses. They’re sleek enough to use for various purposes, from camping to working to wearing under suits and dress pants.

I’ve personally used these in winter and love the comfort they provide while also being flexible enough for running and cycling. They kept me warm on a windy, below-freezing run around Brooklyn and have held up through numerous wash and dryer cycles.

Merino Wool Thermal Underwear for Men

This heavyweight pair is ideal for wearing under snow pants, ski bibs, or waders. They’re between 7 and 9 ounces depending on size, and the extra weight provides warmth and durability. Unlike others on our list, these are 100 percent merino wool—no cotton or synthetic mixed in.

Therefore, they’re super effective at all the things you love about wool—insulating, moisture-wicking, and fighting odor. The weight makes this pair ideal for especially cold weather, but its thickness makes them less versatile. They’re too bulky to wear underneath jeans or casual pants.

Warmknit Long Thermal Underwear for Men

Mack Weldon’s proprietary Warmknit material is a throwback to classic waffle-knit thermal underwear, but with modern fabrics that boost comfort and warmth.

It’s a combination of a soft micro-waffle-knit pattern and Thermolite—a lightweight synthetic insulation polyester—for improved heat retention and breathability. Mack Wheldon blends Thermolite with modal and Spandex—modal to keep them light and Spandex to afford stretch for unencumbered mobility.

Customers report that these are extremely warm and the fit is true to size. The elastic waistband doesn’t droop or sag throughout the day, and the ankles stay in place thanks to a cuff at the hem. Customers were also happy with how the Warmknit thermals held up after multiple washes and wear.

Rho Heavyweight Thermal Underwear for Men

The Rho bottoms from Arc’teryx are heavyweight thermal underwear for days when the temperature dramatically drops. They’re designed to perform on the slopes, but they’ll serve you well on a windy and cold day in the city, too.

The Polartec Power Stretch fabric is made with a nylon face and a brushed, soft polyester inside. These thermals are very durable and wick moisture quickly, keeping you warm and dry even during high-output activity.

The trim fit makes for easy layering under ski pants or jeans, and the laminated zip pocket at the thigh keeps small essentials like keys secure. This pair runs small for some so consider sizing up, though I took my normal size and found them comfortable.

I use the Rho bottoms mostly for lounging around because of the cozy brushed interior. It’s super soft against the skin and feels like a pair of fleece sweatpants. The pocket means they can double as running tights, but since they’re so warm, I only use them if it’s really cold.

The waistband isn’t as wide as others but it still stays in place and doesn’t chafe or get uncomfortable. They’re too hot for high-output activities on mild days, but the brand also makes a lightweight version if you want more versatility.

Lightweight Thermal Underwear for Men

These lightweight men’s long johns are best suited as activewear when the temp isn’t frigid, but cold enough that you need something more than the typical boxer-briefs. Reviews say they will keep you warm into late fall, but you’ll need something warmer for the middle of winter.

The Spandex lends four-way stretch, and the low-profile waistband sits comfortably at the waist without folding or drooping. And the lightweight polyester is moisture-wicking and dries fast.

Reviewers appreciated how warm, light, and durable these pants are, particularly for days that aren’t cold enough to warrant heavier base layers. These pants are best suited to cut the chill on days that don’t require heavy base layers, making them perfect for activities where you’ll warm up fast, like hiking.

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