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Merino wool is a super fiber. Merino T-shirts somehow manage to be comfortable in 95-degree-Fahrenheit heat, and merino hoodies keep you warm well below freezing. Unlike synthetic fibers derived from petroleum, merino wool is natural and renewable.
One sheep can produce 4 to 5 pounds of wool per year. That's because the sheep that make merino wool drink only the purest alpine waters and study the art of comfort under the tutelage of those stuck-up Pashmina goats, who, let's face it, might know a thing or two about wonderfully pillowy softness. Just kidding. Merino sheep do have thinner, softer wool, which has evolved to keep them comfortable across a wide range of temperatures and is comfortable to wear next to your skin. It's unclear whether the sheep learned to do this from Pashmina goats, but I do know that merino wool is a remarkable fabric that's become the cornerstone of my wardrobe.
Yes, even in summer. I've worn merino T-shirts on 100-degree-Fahrenheit days and felt fine, though this is less true if you throw high humidity into the mix—merino sheep do not vacation in the tropics, apparently. Whatever the case, the 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 (in cold water, and hung to dry) over the course of several weeks.
Updated June 2024: Adrienne and I have added a few new T-shirt options, some pants we love, several new bras and underwear, and updated links and prices throughout.
What Does GSM Mean?Start With a HoodieBetter Base LayersReplace Fleece With a Mid-LayerWool T-Shirts? Heck Yes!Socks, Underwear, and BrasEveryday Merino ClothesHow to Care for Merino Wool100 Percent Merino vs. BlendsMerino vs. Synthetic Fibers
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What Does GSM Mean?
Merino wool comes in different weights, which you will frequently see listed as "200 GSM” or something similar. (The GSM refers to grams per square meter, sometimes listed as g/m.) What's important is the scale and where your garment falls on it. At the low end, you have T-shirts and underwear, which are typically 150 GSM, though we have seen some as low as 120 GSM. Generally, anything below 200 GSM will be a good base layer. From 200 to 300 GSM are your mid-layers, and anything above 300 is a heavier garment.
Start With a Hoodie
Photograph: Icebreaker
Icebreaker Merino Quantum III Zip Hoodie$220 $190 at Amazon (women's)$220 $181 at Amazon (men's)$250 at Icebreaker (men's)$220 at Icebreaker (women's)
Merino wool is versatile, but I'd still argue that the best use case for it is as a lightweight mid-layer, like a hoodie. It's warm enough for cool days on its own, surprisingly wind-resistant, and can pair with an outer shell to form a great lightweight day-hiking layering system. It's also a good go-to for the gym or around town.
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 below) 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.
Alternatives
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.
A Hoodie for Kids
Photograph: Minus33
Minus33 Expedition Weight Hoodie$220 at Minus33 (Women's)$220 at Minus33 (Men's)
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.
Base Layers
I'm old enough to remember when a "base layer" was whatever cotton T-shirt you put on. Do you need a special shirt to go hiking? No. Just go hiking. That said, outdoor gear marketing or not, base layers are a thing. If you have any merino already, chances are they're base layers—merino really shines here, as synthetic base layers tend to end up stinking while merino does not. These are the best merino wool base layer tops and bottoms that we've tested.
Photograph: Scott Gilbertson
Smartwool Merino Classic Long Sleeve$90 at REI (Men's)$90 at REI (Women's)
These well-loved Smartwool shirts are popular for a reason: They're just the right weight for a base layer, 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 only 87 percent merino wool (blended with nylon), these are also a good choice for anyone on the fence about trying a wool base layer. Just do it; you'll thank us.
Unbound Long Sleeve Merino Crew$98 at Unbound (Women's)$108 at Unbound (Men's)
This 100 percent merino shift from Unbound is incredibly soft. 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. 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.
Minus33 Midweight Chocorua Long Sleeve Crew$80 at Minus33 (Men's)$80 at Minus33 (Women's Ossipee)
Minus33 calls this a midweight, but I find it the perfect base layer for snowy days. It's nice and soft, and paired with a nice merino hoodie, like the Minus33 Expedition weight hoodie above, it's plenty warm enough for winter hiking. 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.
Bombas Merino Wool Blend Long-Sleeve Shirts$74 at Bombas
If you want a softer shirt, we like these blends, 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 (just don’t get the black color). I will also say that I, Adrienne, am 5'2" and found this shirt to be the perfect length, which means that it will probably be pretty short on anyone taller.
Ibex Woolies Pro Tech Crew$115 at Ibex (Women's)$115 at Ibex (Men's)
If you want a hard-wearing shirt, this one is slightly more expensive and is made of 85 percent merino wool and 15 percent nylon. These are made from Nuyarn, which is a merino wool-specific technology wherein merino wool is wrapped around a nylon core for warmth, lightness, and extra durability. This is a really light base layer that I wear for running and high-aerobic activities when it’s cold. I do have to say that Ibex is whatever passes for a heritage company in this space; the company was founded in 1997, and my parents bought me two sets of Ibex base layers in 2001 that I still wear today, in the year of our Lord 2024. That bodes very well for Ibex’s longevity, and I look forward to seeing whether these replacements also last that long.
Photograph: REI
REI Co-op Merino 185 Base Layer Bottoms$80 at REI (Men's)$80 at REI (Women's)
Don't forget your legs! It never fails to surprise me (Adrienne) how many people put multiple layers of insulation on their top half and leave their legs completely bare. Depending on the weather, I have several different weights of leggings that I can swap in. My favorites are the classic Icebreaker leggings, which have lasted me almost a decade. However, the rest of my family (my spouse and two children) use REI's in-house merino wool base layers and leggings, which are a reasonably priced option and don't irritate my son's sensitive skin.
Photograph: REI
Kari Traa Rose Base Layer Bottoms$110 at Amazon
I (Adrienne) 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. Most major brands offer a women's version of their base layers. However, if you're having a lot of difficulty finding a pair that works, 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.
Replace Fleece With a Mid-Layer
I have nothing against synthetic fleece. It has its place, but I rarely wear it these days. I prefer a hoodie like those above, or a mid-weight jacket or sweatshirt like those here. Merino is better at helping your body regulate its temperature, rather than just keeping you warm like fleece and other synthetics do.
Photograph: Kora
Kora Yardang Jersey$150 at Kora (men's)$150 at Kora (women's)
Kora’s Yardang Jersey is a half-zip midweight mid-layer. It is probably the most versatile thing I have in my wardrobe. It's plenty by itself on a cool spring day but then thin enough to put another layer on top of it when you need more. It's pleasantly breathable and very soft. The Yardang is a blend of 70 percent merino, complemented by 30 percent Himalayan yak wool. It's the softest bit of merino in my collection. If you like this blend, there's also a hat and neck gaiter in the Yardang line.
Photograph: Minus33
Minus33 Expedition Yukon Crew$140 at Minus33 (Men's)$140 at Amazon (Men's)
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 nights, and even as a base layer under a merino 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.
Photograph: Ibex
Ibex Shak Jacket$260 at Ibex (Women's)$260 at Ibex (Men's)
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 (Adrienne), 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.
Photograph: Ibex
Ibex Wool Aire Vest$235 at Ibex (Men's)$235 at Ibex (Women's)
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 (Adrienne) like to layer Ibex's Wool Aire Vest under my regular wool coat if I'm going out for the night or on a long run.
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.
Photograph: Scott Gilbertson
Unbound Merino T-Shirt$88 at Unbound (Men's)$85 at Unbound (Women's)
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 (men's $95, women's $88), aimed specifically at working out, is also quite nice, but it's a tighter cut than the regular T-shirt.
Photograph: REI
Artilect Utili-Tee$90 at Artilect (Men's)$90 at Artilect (Women's)
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 (Adrienne) 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.
Photograph: Icebreaker
Icebreaker Tech T-Shirt$85 $50 at Icebreaker
These Icebreaker T-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$70 at Minus33 (Men's)
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$55 at Paka (Men's)$55 at Paka (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. If you want to go natural fibers but aren't sure you can commit to merino, this makes an affordable alternative.
Unbound Tank Top$70 at Unbound (Women's)$75 at Unbound (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
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.
Photograph: Unbound
Unbound Men's Merino Boxers$45 at Unbound
As with the company's T-shirts, Unbound's boxer briefs stood out for just how soft and comfortable they are. 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$45 at Icebreaker (Men's)
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.
Minus33 100 Percent Merino Underwear$45 at Amazon$45 at Minus33
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.
Woolly Everyday Boxer Brief$27 at Amazon$28 at Woolly
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.
Ridge Merino Merino Wool Boxer Briefs$35 at Ridge Merino (Men's)
These Ridge 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.
Photograph: Branwyn
Branwyn Essential Bralette$48 at Branwyn
Branwyn makes what they call merino wool performance sets. I (Adrienne) 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 recently 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.
Photograph: Scott Gilbertson
Ibex Natural Briefs$35 at Ibex
Branwyn also makes underwear, which I like because it's thick enough to double as a swimsuit if I'm out hiking. But 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.
Photograph: Darn Tough
Darn Tough Merino Socks$25 at Amazon$24 at Darn Tough
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.
Photograph: Carhartt
Carhartt Merino Socks$25 at Amazon$25 at Carhartt
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.
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: a fancier take on the classic thermals with temperature regulation and other technical merits. All that is true, but I've since found 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.
Photograph: Scott Gilbertson
Woolly Longhaul Shop Pant$130 at Woolly
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.
Woolly Long-Sleeve Button Up$70 at Amazon (Men's)$90 at Woolly (Men's)
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.
Mission Workshop Navarro Merino Wool Sweater$165 at Mission Workshop
This is by far the fanciest piece of merino wool clothing I've tested. It's much more at home on streets of San Francisco, when you're out grabbing a burrito at Pancho Villa, than out in the woods, but if you want an upscale look this sweater delivers. It's also incredibly warm and soft, perfect for cool evening strolls about the city.
Ridge Merino Men's Hyde Merino Jogger$125 at Ridge Merino (Men's)
At the opposite end of the spectrum from the sweater above are these super comfy, casual sweatpants from Ridge Merino. These are probably the most comfortable pants I've ever worn. I don't often work out in them, 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).
How to Care for Merino Wool
Most merino products will have care instructions. Most likely it will be to wash cold and lay flat to dry. The latter is important, as hanging wool to dry will stretch it out (because of the water weight). While most merino labels will say the garment can be machine washed, my experience has been that hand-washing merino will extend its life. This is particularly true of very lightweight (150 GSM) merino base layers and T-shirts.
I've never had a problem storing merino in my closet between wears, but for long-term storage, I recommend you take precautions against moths, which are notorious for eating holes in wool. I have lost merino garments to moths.
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If you don't want to smell like mothballs, there are better solutions. I make sure to wash and thoroughly dry whatever I am storing, then I seal it in a compression bag, like this. Another option is to put your merino garment in a cotton bag or otherwise wrap it in cotton and then put it in a plastic bin. It's very important to make sure that the garment is completely dry before using any of these storage methods, otherwise your wool will smell musty and moldy. Other options include storing your garment in a cedar chest, which is a good natural deterrent for moths, or use moth traps or lavender sachets, which will repel the moths.
100 Percent Merino vs. Blends
Should you buy 100 percent merino or should you go for a blend? The answer is … it depends. On the garment in question, the use case, and your preferences. Probably the best way to find out is to try several and see what you like.
For what it's worth, I like 100 percent merino for heavier mid-layers like hoodies or jackets, but I prefer blends for lighter layers. My experience has been that the closer I get to my skin, the more blend I want. Because I don't like synthetic fibers, I usually look for cotton-merino blends, though after trying Kora's yak wool blend, I might be a yak wool convert. There are some alpaca blends out there that are also wonderfully soft (I love everything I've tried from Paka), but alpaca is expensive.
Merino vs. Synthetic Fibers
Which is better? The answer again is … it depends (sorry). But usually merino. By synthetics, I generally mean polyester, nylon, polypropylene, rayon, or blends of these and other fabrics—everything but cotton, wool, and linen.
Synthetics generally win for wicking away sweat, which means they tend to feel drier. They also tend to dry faster, so when it comes to things like socks and underwear, even most "merino" options are often more than 50 percent synthetic. Synthetics are just better at handling moisture. How much this matters depends on a host of personal factors. For example, I feel weird and almost clammy in anything synthetic, so I don't really care how much moisture it wicks away.
The downside to that moisture wicking is that synthetics retain odor. There are some chemical treatments that can help, but I've never tried anything synthetic that was as odor-resistant as merino wool.
Another difference is breathability. Synthetics are passable in this department, but it's where merino really excels. If you're hot and are hiking up an exposed slope toward an open pass and then dropping down into the cool of a forest, merino is your friend, because the breathability means less sweat to cool you when you get out of the sun. Again, how much this matters depends on your body.
The final factor worth thinking about is durability. In some cases, synthetics will last longer than pure merino, particularly in scenarios where abrasion is a major source of wear. To my mind, this is just another reason to choose a merino blend rather than going all the way to synthetics, but it's something to think about if you do a lot of off-trail hiking or rock climbing—any activity where your clothes are going to take a beating.
