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Merino wool is a super fiber. The best merino wool clothing somehow manages to be comfortable in 95-degree-Fahrenheit heat, and merino base layers keep you warm well below freezing. Unlike synthetic fibers derived from petroleum, merino wool is natural and renewable.

Merino wool’s versatility means there’s a bewildering array of blends and options to choose from. Here are our favorite merino wool products that we’ve tested by wearing and washing (usually in cold water, and hung to dry) over the course of months and even years in some cases. Once you’re done here, don’t forget to check out the rest of our apparel guides, like the Best Puffer Jackets, the Best Hoodies, and the Best Hiking Boots.

Updated March 2025: We’ve added new base layers and T-shirts, and we’ve updated links and prices throughout.

Base Layers

To really see how remarkable merino wool is, start at the bottom, with the clothes next to your skin. Merino really shines as a base layer . I’s warmer for the weight, wicks moisture better, and unlike synthetic fabrics, merino stays stink-free for days of wear. These are the best merino wool base layer tops and bottoms that we’ve tested. Be sure to read our layering guide for more on how to put it all together and stay comfortable in any weather.

Ibex Woolies Pro Tech base layer crew is the best lightweight merino base layer we’ve tested. If you want a hard-wearing shirt, this it it. Woolies are Nuyarn (see above), which is 85 percent merino wool and 15 percent nylon—the merino wool is wrapped around a nylon core, which increases the warmth while being lighter (5 oz for the men’s large) and more durable. This is my top pick for all things technical. It’s what I bring hiking, backpacking, and it’s reviews editor Adrienne So’s pick for running, climbing and other high-aerobic activities when it’s cold. I also love the Woolies Pro Tech Bottoms ($115), which are what I bring backpacking in all but the warmest of weather. There’s also a quarter zip version of the shirt if you prefer.

Aside from comfort and warmth, a bit part of the reason we recommend Woolies is that they last. Ibex is what passes for a heritage company in this space; the company was founded in 1997 and has been cranking out merino garment for a long time. Adrienne’s parents bought her two sets of Ibex base layers in 2001 that she still wears today, in the year of our Lord 2025. Properly cared for, Woolies will keep you comfortable warm for years to come.

When I want something a bit warmer than the lightweight Woolies above, I reach for Smartwool’s Classic long sleeve base layer. These may be the most popular merino shirts around, and for good reason: They’re very comfortable, tending to the looser side, feature heavy-duty seams (read: sturdier, longer lasting) that don’t rub, and sit off the shoulder for more comfort when wearing a pack. At 87 percent merino wool (blended with nylon), these are also very durable while remaining lightweight (10.3 oz for a men’s large). This Smartwool shirt, along with the matching pants ($115), have been my constant companions through a chilly Wisconsin winter.

If you’re going to be in serious cold, Minus33 is the company to shop. It calls this a midweight, but I find it the perfect heavyweight base layer for snowy days. It’s nice and soft, and paired with the Minus33 Expedition weight hoodie below, it’s plenty warm enough for winter hiking and snowshoeing. The seams don’t rub, even with a heavy pack on, and the cut is roomy without being too baggy. I’ve been testing this shirt for over a year now and it still looks like it did the day I got it—almost no pilling and no fraying. Note that the women’s version is called the Ossipee, but it’s functionally the same shirt.

The picks above all have what my wife calls “that sporty look,” which the industry refers to as “technical.” This 100 percent merino shirt from Unbound is the opposite: it just looks like a long sleeve shirt. It’s incredibly soft and while it does pill a bit if you run it through the dryer (don’t), it’s proved itself plenty durable—I’ve been wearing it constantly for over a year now and it still looks like it did when I got it. It’s the long-sleeve, base layer twin to our favorite T-shirt (see below). It’s on the thin side for a base layer, which makes it perfect for those cool weather mornings in the shoulder seasons. It’s versatile too; it can be used as a base layer, but it also works as a T-shirt when it’s not too chilly. Fit runs true to size, and if the one you want is sold out, be patient; Unbound frequently updates its stock.

Other Great Base Layers:

• REI Merino 185 Base Layers for $80 (Men’s): Our favorite budget merino base layers, these REI tops and bottoms are comfortable, warm, and considerably cheaper than some of our other favorites. We also love the bottoms and leggings (Men’s/Women’s), which are likewise reasonably priced
• Ridge Merino Aspect Midweight Base Layer for $75 (Men’s): This is one of the rare base layers that you can actually where as just a T-shirt around town and you won’t look like you just drove in from the trailhead, which makes it a bit more versatile then some of the others here. If you want something multi-use, this is a good option.
• Bombas Merino Wool Blend Long-Sleeve Shirts for $74: If you want a softer shirt, we like these, which are 50 percent wool and 50 percent Tencel, a lightweight eucalyptus fiber. Tencel is very silky to the touch, which makes this shirt particularly versatile—it’s warm when you need it and provides UPF 50 protection if you want to wear it in the sun.
• Kari Rose Base Layer Bottoms for $110: I am 5’2″ and struggle to find clothing options that will fit—especially ones that are meant to fit next to the skin. As high-quality as a base layer may be, it won’t keep you warm if it rucks up around your waist or sags below your hips. Kari Traa’s leggings have a very high waist that helps keep them up. The patterns are also pretty, for those of you who object to parading around the lodge in what looks like pajamas. —Adrienne So
• Artilect Boulder 125 Leggings for $120 (Men’s): These base layer pants were my introduction to Nuyarn and they’re an excellent choice for anything active—they have a ton of stretch and flexibility thanks to the many fabric panels and stitch lines that actually make sense. They’re quite thin and quite tight, but I really like these for running on cool mornings.
• Ridge Aspect Midweight Merino High Rise Bottoms: These are another great option fro women looking for something that can be worn around town as well as on the trail. My daughter has even worn them under shorts for no-gi juijitsu and they’ve held up great, which is a testament to their durability.

Merino Mid Layers

Fleece has its place, but I rarely wear it these days. I prefer merino for my mid layers. It’s better at helping your body regulate its temperature. The one place fleece still wins for me is backpacking, it’s almost always lighter for comparable warmth, at least in mid layers.

An Icebreaker hoodie was my introduction to merino wool, and it remains my favorite jacket I’ve ever owned. Alas, after about 10 years, mine had a run-in with moths (see our care guide) and had to be retired. Mine was not the exact style pictured, but very close to it. This jacket is 100 percent merino and incredibly warm, despite not being all that thick. That makes it a great option for days when the weather may vary considerably–it’s warm enough for a cold morning but won’t be a burden in your pack the rest of the day. This is on the tight-fitting side, so if that’s not your thing (and it’s not mine), get the next size up.

Best Heavyweight Hoodie

Like the Northern Lights or the McRib, the thickest Ibex wool hoodie appears irregularly and with some fanfare. The Mammoth Hoodie is indeed a big, furry beast of a garment—it’s basically the weight of the classic American Giant hoodie but made of 85% wool cut with 15% nylon for added warmth and stretch. Ibex says it’s the warmest hooie they’ve ever made, and in my week of testing, I’ve used it in place of a jacket in mid-30s temps. It has an athletic cut with zippered pockets and thumb holes. I do wear a stocking hat with it in the cold because the scuba hood is meant to fit under a helmet which means it’s too small to provide enough warmth for my large shaved head on its own. —Martin Cizmar

Other Great Hoodies:

• Ibex Men’s Indie Hoodie ($170): WIRED’s commerce director, Martin Cizmar, tested this midweight wool hoodie and says it’s now one of his “absolute favorite pieces of clothing.” See what good wool does for you? Makes you a fan. The cut on this one is sporty but not too tight that you can’t layer under it. The thumb loops, zippable tall neck, and hood make it a lot more versatile than a typical wool long-sleeve shirt. Cizmar says it’s perfect for general winter use, whether you’re doing yardwork, biking, or tossing a football around in the park.
• Ridge Merino Hyde Hoodie ($150): This 100 percent merino wool hoodie uses a 275 GSM terry weave merino that doesn’t feel like wool. Like the Icebreaker, it’s a midweight hoodie, perfect for those cool days in autumn and spring. It features a full length zipper, thumb holes in the sleeves and zipper on the pocket. I really like this hoodie, except for that fact that it is cut on the longer side, which makes it look a little large, even though it isn’t. There’s a women’s version as well.

There’s a dearth of merino wool for kids. Perhaps the price for something that kids may outgrow in a few months makes the economics unappealing for manufacturers. Whatever the case, very few companies offer kids-size merino (see below for more). In fact, this Minus33 hoodie isn’t available in kids’ sizes, but the extra-small women’s fit my 10-year-old perfectly and continues to fit her as an 11-year-old. You’ll want to check the fit chart on Minus33 for your own kids, but if they do fit, this is a fantastic hoodie. It’s plenty warm (and my daughter is always cold) and durable enough to stand up to kid life, climbing trees, and running through the woods, and the hand warmers pair well with mittens on cold days. Best of all when kids are involved, this one can be machine-washed and tumble-dried. It won’t shrink or lose its shape, and the colors won’t bleed.

Minus33 calls this an expedition-weight base layer, but for those of us not climbing Mt. Washington at dawn in a windstorm, it’s really more of a mid-layer, a pullover sweatshirt—an insanely warm, comfy pullover sweatshirt. My testing time was limited. After a month, my wife stole it and now refers to it as a security blanket and has said it’s the one item of clothing she cannot live without.

I did manage to try it everywhere from the beach on cool mornings to around the campfire on winter evenings, and even as a base layer under a puffer jacket when the temps dropped below freezing last winter. In all those situations I stayed plenty warm. The looser fit means it can go over a base layer, but isn’t so bulky you can’t put a jacket over it.

A growing number of studies have shown that there are PFAs—hormone-disrupting chemicals that are commonly used in a number of plastics—in ordinary sportswear, like leggings and sports bras. If you, like me, are on a quest to replace your polyester clothing with natural fibers, then Ibex’s 100 percent merino wool Shak Jacket is the natural candidate to replace your (my) worn-out Patagonia Better Sweater ($159).

I took this jacket on a trip this spring to Ireland. It’s surprisingly dense and soft to the touch. It kept me warm on blustery 30-degree days, layered easily under my rain jacket and over my tank top, and looked sleek enough to go out to dinner. In western Ireland, at least (“I like your jumper!” said many an Irishman). It doesn’t pack down quite as compactly as a synthetic layer might, nor is it as light, but it looks much nicer and it won’t feel like slime on your skin when it gets wet. —Adrienne So

If you have concerns about using goose down jackets as an insulation layer, merino wool is also a decent substitute for synthetic insulation. Vests are like the cheat code of layering if you like to keep your core warm but your arms mobile, or you want to get an extra soupçon of warmth without adding too much bulk. I like to layer Ibex’s Wool Aire Vest under my regular wool coat or rain shell, if I’m going out for the night or on a long run. —Adrienne So

The Best Merino Wool T-Shirts

Wool might not seem like a good choice for a summer T-shirt, but merino is surprisingly comfortable even when it’s warm. To a point anyway. On humid days over about 90 degrees Fahrenheit, I usually go with cotton or linen, but anything under 90 and I’m wearing merino. There are far more merino T-shirt options out there than we can cover, but here are some of our favorites. Note that while I am a fan of crew neck styles, most of these are also available as V neck shirts.

These are my absolute favorite T-shirts. They are the softest, best-made, best-fitting T-shirts I’ve ever worn, merino or otherwise. Yes, they are that good. They’re incredibly versatile. I’ve worn them doing everything from backpacking in the summer heat to rolling jiujitsu to sitting around the fire on cool autumn evenings. They’re never anything but comfy. I also like that they have no logo. Unbound’s Active Merino T-shirt ($95), aimed specifically at working out, is also quite nice, but it’s a tighter cut than the regular T-shirt.

When I’m heading out hiking, backpacking, paddleboarding, just about anything outdoors, this is the T-shirt I reach for first. It’s lightweight (84 percent 145 GSM merino, 16 percent synthetic) jersey knit is soft and comfortable—not too hot in the sun (it’s also UPF Rating 20), warm enough when it’s cool. It’s also durable (I’ve been rolling jiu jitsu in this shirt for years and it’s fine) and machine washable. You can even throw it in the dryer, no need to baby this T-shirt.

Artilect’s blend of merino wool and Tencel (a fiber made from eucalyptus) is shockingly lightweight and versatile. This summer, the Utili-Tee became my favorite shirt for climbing and backpacking. It was soft and comfortable when I was in the tree shade, and then magically stayed light and breathable when I broke through the tree line and the temperature suddenly rose by 15 degrees in the sunlight. The flat seams didn’t cause chafing on my shoulders or waist through backpack straps or a harness, and even though it’s a flattering slim fit, it didn’t constrict the movement of my shoulders or arms in any way. —Adrienne So

Other Great T-Shirts:

• Icebreaker Tech T-Shirt for $85: These Icebreaker merino wool shirts were one of my gateways to merino wool. They’re warm, yet somehow cool, and surprisingly good at stopping the wind. These shirts aren’t great in humidity; for that, I’d probably go with a blend. Note that some of Icebreaker’s T-shirts are blends, so check the details on your favorite design before you invest.
• Minus33 Algonquin T-Shirt for $70: Minus33 knows a thing or two about keeping you warm. The company is in New Hampshire, after all. This 170-GSM T-shirt is comfortable, with a loose cut that works well over a base layer on cool mornings or as a T-shirt during warmer parts of the day. It’s a great all-around choice for all but warmest of summer days.
• Paka Tee for $55 (Women’s): This isn’t merino—it’s a blend of organic cotton and Alpaca wool. But it’s such a nice, comfy T-shirt I’m including it here.
• Arms of Andes Alpaca Wool T-Shirt for $75 (Women’s): This might be a merino wool guide, but we also feature quite a few alpaca items, including this T-shirt, which I love for its surprising warmth. This is not a heavy shirt and yet it manages to be quite warm, especially worn over a base layer in winter, it does an excellent job of insulating and breathing at the same time.
• Unbound Merino Tank Top for $70 (Men’s): Want a cooler option for hot days? This tank top is perfect for warmer, humid climates. It’s 100 percent merino (175 GSM) and doesn’t have any logo or tag, which we like. It does go in and out of stock frequently, so if it’s sold out, check back later, Unbound frequently adds more stock.

Socks, Underwear and Bras

You could argue this is the true base layer, but we’ll skip that and just say that merino wool underwear, socks, and bras are so much nicer than their synthetic counterparts. If you haven’t tried it yet, you’re in for a treat. After testing dozens of each, these are our favorites.

While merino wool is very soft, most products in this category are blends, usually with some form of nylon. Darn Tough socks are a WIRED favorite. They’re great for skiing, hiking, climbing, and just about anything else you want to do. These blends vary by weight, but most of them are around 50 percent nylon and 50 percent merino, which makes them dry a bit faster than pure merino while remaining plenty warm and comfortable. Darn Tough’s socks also last. Mine are going on two years now without a worn area or hole in sight.

Minus33 socks are my personal favorite merino socks. I have several pairs of the lighweight and midweight and even one pair of the expedition, though those are so thick and warm I rarely wear them (they’re perfect with the temps drop below 0F though). My favorite are the Lightweight Mountain Heritage Boot Wool Socks, which are perfect for hiking or wearing around town. Minus33 doesn’t publish a blend breakdown for these, but I would guess they’re about 60/40 wool to nylon, with plenty of both softness and stretch to them.

Other Great Socks:

• Carhartt Midweight Merino Wool Blend Crew Sock for $22: The weird thing about socks is that, as a warm-weather lover, well, I hate socks. Every day with socks is a kind of failure. That said, these Carhartts (gifted to me by a friend who was worried that I wandered about in sockless sandals in the snow) are really nice. They’re incredibly warm and soft, and they never smell.

The phrase “wool underwear” might conjure images of some lumberjack from the 1800s with hair growing through the weaves of his itchy, hot long johns, but that’s not what the merino underwear we’ve tested is like. In most cases these are blends, with some nylon as well.

Thanks to WIRED readers for pointing out Woolly to us. These 100 percent merino (190 GSM) boxers are fantastic and affordable. They ventilate well and adjust to changing conditions to keep you comfortable even on days when the weather starts hot and ends cold, or as I like to call it, hiking in the mountains. They’re on the shorter side with a 4-inch inseam, but Woolly makes the same thing in a longer cut.

These are the only 100 percent merino underwear I’ve tested (there’s elastic in the waistband, but it’s surrounded by wool), and they’re also some of my favorites, especially in cold weather. These are longer than any of the other boxers I’ve tried. These are 170 GSM, making them a little lighter, but because they merino content is higher, these are the warmest I’ve tested. After years of testing merino underwear, these are my favorite on all but the hottest days.

Other Great Underwear:

• Unbound Merino Boxers for $45: Unbound’s boxer briefs are very soft and comfortable. These are 84 percent merino wool, 12 percent nylon, and 4 percent Spandex, so they do have a bit of stretch to them. The 180-GSM merino is light enough for even the warmest of days.
• Icebreaker Merino Anatomica Boxers for $45: Another great pair of boxers, these Icebreakers are a very similar blend (83 percent merino, 12 percent nylon, 5 percent elastane) to the Unbound above, but lighter weight at 150 GSM. They fit true to size and are on the shorter side in terms of length. Icebreaker also makes a long version that I tested as well. They’re virtually the same, just a bit longer.
• Ridge Merino Wool Boxer Briefs for $35: These Ridge Merino boxers are 83 percent merino wool (170 GSM), with the remainder of the fabric made of nylon and spandex. The blend gives them a stretchier feel, and they’re nice and soft as well. They generally fit true to size, and have a 6-inch inseam.

Branwyn makes what they call merino wool performance sets. I am a fan of Branwyn’s clothes, all of which are Oeko-Tex 100 certified, which means every component of the clothing has been independently tested against a list of up to 350 toxic chemicals. This is one of the most widely known and respected labels for consumer safety. These fit true to size. (I suppose it’s important to note here that I’m a small-busted woman, and that Branwyn makes a Busty Bra ($58) if you need more support.)

However, this is not quite supportive enough to go running, which is why Branwyn launched the Racerback Bra ($75). It’s pretty impressive that Branwyn got merino wool to be compressive enough for medium impact activity. I like that it offers full coverage, with no annoying small and twisty straps and no padding. It precludes the need to change from cotton “everyday” underwear to tight nylon “sport” underwear every time I want to do something active, which is all the time. —Adrienne So

Other Great Underwear:

• Ibex Natural Briefs for $35: if you’d prefer a thinner option, Ibex’s natural briefs feel much more like your basic, breathable cotton undies. I usually line dry my merino wool, but these look enough like my cotton briefs that I threw them in the dryer and shrank them. If this sounds like you, you might want to size up. —Adrienne So
• Icebreaker Siren Bra for $35: I only have one Branwyn bra, but these are the bras that I wear every other day of my life. Like Icebreaker’s men’s underwear, they are 83 percent merino, 12 percent nylon, and 5 percent elastane, and they fit true to size. —Adrienne So
• Wool& Roam Merino Bra for $70: Wool&’s merino fabric is the softest I’ve felt in my entire life, probably because the blend has a much lower merino content at 68 percent merino wool, 25 percent nylon and 7 percent spandex. I tried these and Wool&’s underwear. They’re insanely soft, but overpriced when compared to our other options, and you have to size up. —Adrienne So

The Best Everyday Merino Clothes

I’ll confess that when I launched this guide years ago I thought of merino wool mainly as an outdoor-related fabric. It is great for that, but I’ve since discovered that merino is good for everything, especially travel, since it can be worn several times without any odors. I’ve tried merino pants, dress shirts, workout clothes, hats, and more. The best stuff I’ve tested is below.

Merino wool pants? Yes. Merino wool all the things. I was skeptical, but I actually love these pants. Don’t let the name fool you, they’re not shop pants in the sense that Carhartts are. They’re much lighter and have a more fitted cut, but there are several leg pockets and a loop you could maybe attach a tool to. Mostly, though, they’re just nice casual pants—not too heavy, not too light. They’re a blend of 75 percent merino wool (450 GSM), 21 percent bamboo, and 4 percent elastane, which gives them just a bit of flex.

These super comfy, casual sweatpants from Ridge Merino are some of the most comfortable pants I’ve ever worn. I don’t often work out in them, I’ve never actually jogged in them (or yogged, it might be a soft j), but they’re great around the house. These are 100 percent merino wool (275 GSM) with what Ridge calls a terry fabric (they feel like sweatpants).

What do you do when you’ve got nice merino wool pants, merino wool underwear, and merino wool socks, but you need something nicer than a T-shirt? That’s where this button-down long-sleeve shirt from Woolly comes in. It’s a little more formal, what you might call business casual, but still comfortable and soft. The only thing I am not quite so fond of is the slightly shimmery look, but that’s just personal preference.