Merino wool is a super fiber. The best merino wool clothing somehow manages to be comfortable in 95-degree 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, although we do machine dry them just to see what happens) 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 Merino Wool T-Shirts, Best Base Layers, Best Puffer Jackets, Best Hoodies, and Best Hiking Boots.
Updated November 2025: We’ve added several new T-shirts from Huckberry's Proof brand and Taylor Stitch, a Minus33 base layer for extreme cold, Ridge Merino's excellent Cloudripper merino-grid fleece blend, Wool&'s Roam Convertible Wrap Bra, and Proper Cloth's exquisite dress shirt.
Why Is Merino Wool So Great? AccordionItemContainerButton LargeChevron Merino wool is great because you're stealing a sheep's ability to keep itself warm or cool based on the temperatures it's in, a process often referred to as thermoregulation. If you've only ever worn the sort of itchy wool sweaters your proverbial grandmother supposedly made, you might wonder what all the fuss is. The answer is that Merino sheep 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. Wool is sustainable, too. 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 that softer wool though, and merino wool is a remarkable fabric that's become the cornerstone of my wardrobe. What Does GSM Mean? AccordionItemContainerButton LargeChevron 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 or T-shirt. From 200 to 300 gsm are your mid-layers, and anything above 300 is a heavier garment. If you're more familiar with synthetic ratings like those often used on fleece, know that, in my experience, about 120–160 gsm wool corresponds to 100-weight fleece, 160–200 gsm wool roughly matches 200-weight fleece and 200+ wool is like 300-weight fleece. In every instance, the wool is warmer because it's better at trapping heat, especially in the wind. (That said, there are reasons to go with fleece at times, like how incredibly lightweight it can be.) What Is Nuyarn? AccordionItemContainerButton LargeChevron Nuyarn is a merino wool/synthetic hybrid weave, wherein merino wool is wrapped around a nylon core for warmth, lightness, and extra durability. The idea is to get the temperature regulation benefits of merino, but to add some of the longevity of nylon. In my experience, Nuyarn mostly works. It's our top pick for base layers, though I find it less necessary in more casual garments, where I prefer 100 percent wool. How to Care for Merino Wool AccordionItemContainerButton LargeChevron 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 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. The exception is Minus33's Microweight Raglan short sleeve T-shirt, which is machine-washable and dryer-friendly. Having done both to mine for over a year, I can vouch that it does indeed hold up. 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. 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 AccordionItemContainerButton LargeChevron 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. One advantage to blends is that they're stretchy, which makes them better for active pursuits like hiking, rock climbing and the like. 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, with Nuyarn being my top pick for base layers. There are also some alpaca blends out there that are also wonderfully soft (I love everything I've tried from Paka and Arms of Andes). If you're one of the rare people who do find merino itchy, you might be allergic to lanolin, which is the skin oil produced by sheep. Alpacas don't make lanolin, and the fibers are thinner and finer than merino. That makes alpaca warmer and softer, but it's also more expensive. Merino vs. Synthetic Fibers AccordionItemContainerButton LargeChevron 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.
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. It's warmer for the weight, wicks moisture well, and unlike synthetic fabrics, merino stays stink-free for days of wear. Be sure to read our layering guide for more on how to put it all together and stay comfortable in any weather. We also have a separate guide to the best base layers if you want know all your options, but here are our top merino picks from that guide.
Best Lightweight Base Layer
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.
Best Heavyweight Base Layer
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