Made from a premium blend of Merino wool and lyocell, these long johns offer a silky-smooth feel—without the need for a silk budget. Merino wool keeps you cozy without turning you into a human sauna, and thanks to its natural antimicrobial properties, you can stretch out your wash day just a little longer (we won’t tell). The streamlined fit means no awkward bunching under your layers, so you can stay warm without resembling a walking marshmallow. In fact, these are some of the sexiest long johns ever—so if your current sleepwear consists of a questionably threadbare T-shirt and some mystery-fabric sweats, consider this your upgrade.
Best Thermal Underwear for Getting Active: Lululemon Seamless Base Layer Tights
Understanding Lululemon’s fits is one thing, but the brand’s true north is comfort. The Vancouver-based label has already claimed prime real estate in closets everywhere for workout gear—and now, they’re making a play for what you wear underneath it, too.
Their latest base-layer bottoms are built from a performance-driven blend of nylon, Merino wool, and lyocell, making them durable, stretchy, and, most importantly, stink-resistant. (No one wants their post-workout musk lingering longer than their actual workout.) But the real kicker? They’re ergonomically designed for both support and room. And if you’re wondering why a word typically reserved for desk chairs is popping up in the world of long underwear, here’s the deal: these are shaped to follow your body’s natural contours, providing a snug-but-not-strangling fit that keeps everything in place without any awkward tightness. Sure, they come with a premium price tag, but when it comes to long underwear that actually fits your shape instead of feeling like a generic compression tube? That’s basically priceless.
Best Era-Authentic Thermal Underwear: Hemen Ikar Long Johns
These are the thermal underwear your favorite style icons would have worn—if they had any sense. The French undergarments label Hemen channels old-school craftsmanship so authentic you’d half-expect to find these in a 1940s military surplus catalog (right next to a tin of mystery rations).
Made from organic cotton with a 2×2 ribbed jersey knit. These long johns may look like they’ve time-traveled from decades past, but they deliver modern-day comfort. And those three front buttons? A vintage-inspired touch that’s not just for show—they make getting in (and, more importantly, out) of these thermals a breeze.
Best Thermal Underwear for the Outdoors: Arc’teryx Rho Heavyweight Tights
Arc’teryx somehow sits at the crossroads of “cool guy flex” and “serious outdoor gear,” and naturally, they’ve found a way to make thermal underwear look downright wearable on its own. Their heavyweight Polartec pants, feature patented Power Stretch fabric that moves with you—so you get warmth without the feeling of being shrink-wrapped.
The exterior is a soft, durable nylon, while the interior boasts a smooth brushed fleece that traps heat and wicks away moisture. And the best part? A small thigh pocket, perfect for stashing your lip balm or headphones while you’re catching your breath on the slopes (or just flexing at the après-ski lodge).
More Thermal Underwear We Love
L.L. Bean Cresta Wool Ultralight 150 Tights
Smartwool Classic Thermal Merino Tights
Todd Snyder Woolrich Technical Merino Long Johns
Patagonia Capilene Thermal Weight Tights
Mack Weldon Warmknit Long Underwear
What to Look for in Thermal Underwear
Long johns aren’t really about making a statement, so colors and patterns don’t matter too much. What does matter, though, is fit and material. For maximum warmth retention, thermal undies should be snug but not overly restrictive. Oh, and flatlock seams are a must to prevent chafing; that should be non-negotiable.
When it comes to fabric, cotton is always a safe bet, but it absorbs moisture, which can actually make you colder. Synthetic blends—polyester, nylon, spandex—are quick-drying and durable, but have a bad habit of trapping odors. Merino wool, on the other hand is soft, moisture-wicking, naturally odor-resistant, and keeps you warm without adding bulk—and it’s one of our go-to winter fabrics for those exact reasons.
Bottom line? Shimmying into a pair of thermal undies on a freezing day should feel like unlocking a level of toasty the lesser-equipped masses can only dream of.
How We Test and Review Products
Style is subjective, we know—that’s the fun of it. But we’re serious about helping our audience get dressed. Whether it’s the best white sneakers, the flyest affordable suits, or the need-to-know menswear drops of the week, GQ Recommends’ perspective is built on years of hands-on experience, an insider awareness of what’s in and what’s next, and a mission to find the best version of everything out there, at every price point.
