As your next-to-skin article of clothing, a baselayer plays a fundamental role in pulling moisture away from the body and regulating core temperature. It’s far easier to justify purchasing a nice down jacket, but a baselayer can be just as important for activities like skiing, hiking, and climbing. To start, avoid cotton (like the old adage “cotton kills”). You’ll need a fabric that will keep you warm when wet and dry out quickly, and merino wool and polyester are the most common choices. Below are our picks for the best baselayers of 2023. For more information, see our baselayer comparison table and buying advice below the picks.

Our Team's Baselayer Picks

Best Overall Baselayer

1. Smartwool Classic Thermal Merino 1/4 Zip ($115)

Smartwool Classic Thermal Merino Quarter-Zip Base Layer Top (deep navy)Material: 100% merino wool
Category: Midweight
Weight: 10 oz.
What we like: Extremely soft, warm, and resists stink.
What we don’t: Pricey, too warm for high-output activity, requires good care to last.

Smartwool has been the industry leader in baselayers for years, and merino wool is the most sought-after material for the job. Made with 100% merino (many of the baselayers below are blends or synthetics), the Classic Thermal Merino 1/4 Zip is the whole package: It’s warm, super soft against the skin, resists moisture, and doesn’t hold stink like the polyester options on the list. All in all, it’s a great baselayer for skiing and other winter sports, and even has a UPF 50+ rating for use as an outer layer in more mild weather. Based on the popularity of the Smartwool Classic Thermal, it’s made in a number of versions, including a Crew ($110) and Hoodie ($140). But when active, we appreciate the ability to lower the zip and regulate heat.

The Smartwool is the full package, but merino wool isn’t cheap: You can save with one of the blends or polyester baselayers below, including Patagonia’s popular Capilene. That said, we far prefer merino for its coziness, warmth, and resistance to smell. With polyester, you’ll likely have to wash and change your baselayers quite frequently, whereas wool keeps performance high over the course of a multi-day backcountry or ski trip. The primary downsides to consider are merino’s lack of durability—particularly if you frequently throw it in the dryer—and compromised breathability: In general merino doesn't dump heat or moisture as well as synthetic materials, which are our preferred choice for high-output activity. But for many, the tradeoffs are worth it for the high levels of comfort, warmth, and performance. Among the growing cadre of merino options, we think Smartwool’s Classic Thermal provides the best balance of versatility, quality, and value.
See the Men's Smartwool Classic Thermal  See the Women's Smartwool Classic Thermal


Best Synthetic Baselayer

2. Patagonia Capilene Midweight Crew ($79)

Patagonia Capilene Midweight Crew (baselayer_)Material: 100% polyester
Category: Light/midweight
Weight: 6.2 oz.
What we like: Cheaper and more durable than merino wool.
What we don’t: Not quite as soft.

Choosing synthetics over merino wool has clear upsides, the most notable being cost, durability, and breathability. For around $40 less than the Smartwool above (the comparable Zip-Neck version is $26 less), the polyester Capilene Midweight by Patagonia offers similar warmth and steps up the game in terms of moisture-wicking capabilities. And it likely will last for many seasons—we have Capilene tops that are multiple years old and counting despite heavy use. And while synthetics aren't blameless when it comes to their environmental impact (they often rely on fossil fuels for production and can leach plastics into the water with each washing), it helps that Patagonia crafts the Capilene Midweight with 100% recycled materials.

What do you sacrifice by going with a synthetic baselayer? Polyester is decently comfortable but not as soft against the skin, and it doesn’t regulate body temperature or repel odor quite as well as wool. This doesn’t mean that your Capilene will get stinky super quickly—and Patagonia has made strides in this area with an anti-odor HeiQ Fresh treatment—but you will find yourself putting it through the wash more often. But wool can be finicky, oftentimes too warm, and not everyone wants to spend $100 or more on a baselayer—which is why we love Patagonia’s Capilene line. For more warmth, try the Capilene Thermal Weight.
See the Men's Patagonia Capilene Midweight  See the Women's Patagonia Capilene Midweight


Best Budget Baselayer

3. Helly Hansen Lifa Stripe Crew ($45)

Helly Hansen Lifa Stripe lightweight base layerMaterial: 100% polypropylene
Category: Lightweight
Weight: 5.1 oz.
What we like: Wicks moisture well and a great value.
What we don’t: Not as warm as other baselayers on this list.

There’s a lot to like about this lightweight active baselayer from Helly Hansen. At just $45, it’s one of the cheapest options on this list yet still will keep you dry and decently warm in most conditions. The headliner is the Lifa fabric, which is made from Polypropylene and specializes in wicking moisture away from the skin (it does so much better than polyester). Along with a nice athletic fit, the Lifa Stripe is great for active skiers and other high-output activities like climbing and hiking.

The downside of Polypro compared to polyester or nylon is that it isn’t as warm. The Lifa Stripe Crew falls into our lightweight category, meaning that it provides some insulation but requires a good midlayer or insulated shell in cold conditions. It’s worth the tradeoff for high-output use, but if you prefer warmth over breathability, check out REI’s budget-oriented polyester lineup (including the $40 Lightweight Crew below). And it’s worth noting that Helly Hansen now offers the midweight Lifa Merino Crew ($100), which features a merino wool exterior and Polypro lining.
See the Men's Helly Hansen Lifa Stripe  See the Women's Helly Hansen Lifa Stripe


Best Lightweight Baselayer for Mild Weather

4. Outdoor Research Echo Hoodie ($75)

Outdoor Research Echo HoodieMaterials: 100% polyester
Category: Lightweight
Weight: 4 oz.
What we like: A lightweight, free-flowing, and breathable top for mild conditions and high-output activity.
What we don’t: Not as soft or odor resistant as merino; material is prone to pilling and snagging.

Warm summer days call for a certain kind of baselayer—one that’s thin and free-flowing, breathable, and quick-drying. Outdoor Research’s Echo collection nails the formula, with 100% polyester material woven into a variety of styles, including everything from tanks and short-sleeve shirts to quarter-zips and the Hoodie here. The Hoodie stands apart in its versatility: wear it as a breathable baselayer on a high-output spring ski tour, a winter running shirt, or as a sun hoody for bluebird days on the rock. Whatever your use, the hood is a really nice addition that extends the Echo’s warmth, coverage, and sun protection above the neck.

The Echo is an incredibly breathable baselayer and one of our go-to sun shirts, but it does have a few shortcomings. The fabric is prone to pilling and snagging, and lacks the soft next-to-skin feel of merino offerings like the Smartwool Classic or Ridge Merino Aspect. And despite Outdoor Research’s use of ActiveFresh Odor Control, the Echo is also known to hold on to stink. Finally, in terms of sun protection, it has a lower UPF rating than most sun shirts (15 to 20, depending on color). But minor gripes aside, the Echo manages moisture better than most offerings here, making it one of our favorite baselayers for mild conditions or high-output activity in any season.
See the Men's Outdoor Research Echo Hoodie  See the Women's OR Echo Hoodie


Best Heavyweight Baselayer for the Cold

5. Patagonia R1 Air Zip-Neck ($119)

Patagonia R1 Air Zip Neck baselayer (grey)Material: 100% polyester
Category: Heavyweight
Weight: 10.2 oz.
What we like: Warm for the weight yet still breathable and quick-drying.
What we don’t: Too warm for most baselayer applications.

Patagonia’s R1 collection has long been a staple of their lineup, and the R1 Air more recently joined the team with a highly technical design. Using hollow-core yarns and zig-zag patterning, the 100%-recycled polyester fabric traps heat yet allows air to pass from the inside out, resulting in a breathable yet warm layer that’s impressively lightweight. And when you do start to sweat, the polyester effectively wicks moisture and dries out quickly. Patagonia rounds out the build with a functional 1/4-zip design to trap warmth or release excess heat, sleek off-shoulder seams, and a small zippered chest pocket. It all adds up to a wildly modern, high-performance baselayer and one of the warmest offerings here.

Technically considered a fleece, the R1 Air toes the line between our baselayer and midlayer categories. As a baselayer, it’s decidedly heavyweight, which means you’ll want to save it for particularly cold winter days. On the other hand, it provides less warmth than the 100% wool Woolx Glacier Long Sleeve Crew below, although the focus on breathability boosts its appeal for high-output pursuits (and it’s around $30 cheaper to boot). Patagonia also offers its latest R1 Air in both Crew and Full-Zip Hoody versions, the latter of which is best suited for midlayer use.
See the Men's Patagonia R1 Air Zip-Neck  See the Women's Patagonia R1 Air Zip-Neck


Most Durable Baselayer

6. NW Alpine Black Spider Hoody ($135)

NW Alpine Black Spider Hoody_Materials: 92% polyester, 8% spandex
Category: Midweight
Weight: 11 oz.
What we like: Durable enough to be worn as an outer layer.
What we don’t: Expensive for polyester.

NW Alpine certainly isn’t a household name, but this small Portland, Oregon, company designs and constructs alpine climbing apparel on par with the best. Although they only make a handful of items, each of their products is a study in quality over quantity. And their Black Spider Hoody is one of our favorite baselayers: It’s comfortable, warm and breathable, and has unmatched durability. In fact, we’ve put ours through six years of climbing abuse—much of the time without a jacket over top—and it has yet to develop any holes or tears.

All that said, the Black Spider Hoody won’t earn you too many style points: It lacks the odor resistance of merino and is available in only a few simple colors. Furthermore, $135 is a hefty price tag for a polyester baselayer, and it can often be hard to find in stock online or in stores. However, the most impressive durability of any baselayer we’ve worn—combined with features like an under-the-helmet hood and chest zip—set the Black Spider Hoody apart as a highly functional and long-lasting performance piece. 
See the Men's NW Alpine Black Spider  See the Women's NW Alpine Black Spider


Best of the Rest

7. Smartwool Classic All-Season Merino ($90)

Smartwool Classic All-Season Long Sleeve_Materials: 88% merino wool, 12% nylon
Category: Lightweight
Weight: 6 oz.
What we like: A great option for cool days and summer nights.
What we don’t: Thin materials require more care.

We’ve already listed the Smartwool Classic Thermal as our top pick, but we’d be remiss not to include another stellar baselayer in the Classic All-Season Merino. The build quality is similar: Smartwool adds 12% nylon to the mix for a boost in durability, the weight goes down significantly to 6 ounces (the lack of the zipper matters here too), and you get the same minimalist seams for comfort. Compared to the warm Classic Thermal above, the All-Season is lighter in weight and ideal for uses like spring skiing, shoulder season hiking, and cool summer nights. You’ll feel like you are wearing much less baselayer, but the boost in coziness and moisture-wicking capabilities are still there.

It’s worth noting that Smartwool also offers its techy Intraknit Thermal Merino, which splits the difference between the Classic All-Season here and the Classic Thermal above. This performance piece is nearly half polyester/elastane (it’s 53% merino), incorporates low-profile seams, and has body mapping with mesh panels throughout for improved ventilation. We haven’t yet had the chance to give the Intraknit baselayer an extended test, but it’s an intriguing option for high-output activities in cold weather when you want a layer that’s both warm and exceptionally breathable. But for mild summer temperatures, the Classic All-Season is $40 less and likely all the insulation you’ll need. For another lightweight merino option with added durability and stretch (but less wool), check out Outdoor Research’s Alpine Onset Merino Crew.
See the Men's Smartwool Classic All-Season  See the Women's Smartwool Classic All-Season


8. Patagonia Capilene Air Hoody ($159)

Patagonia Capilene Air HoodyMaterials: 51% merino wool, 49% polyester
Category: Midweight
Weight: 6.9 oz.
What we like: Scuba-style hood is one of our favorite designs; excellent warmth for the weight. 
What we don’t: Lacking in abrasion resistance.

Patagonia’s Capilene collection is legendary in the world of baselayers, running the gamut from thick, thermal-weight designs to lightweight T-shirts and long-sleeve layers for hiking. The midweight Capilene Air Hoody is a real standout in the lineup, merging functional warmth with a thoughtful feature set and nice sustainability slant. We love the scuba-style hood in particular: It adds an incredible amount of warmth, offers great coverage without restricting vision, and has a low-profile shape that easily slides under a climbing or ski helmet. On blustery and cold winter days when you really need to hunker down in your layers, it's a nice alternative to a balaclava that's much easier to pull on and off.

What’s not to like with the Patagonia Capilene Air Hoody? First, despite the healthy amount of polyester in the construction, we developed multiple holes and runs on our hoody in a matter of weeks. We also found that the knit-like exterior is noticeably permeable to wind, and the fabric tends to pill and act as a catch-all for hair, fuzz, and more. In other words, the Capilene Air works best under another layer or two. But with great odor resistance, impressive wicking and drying properties, and one of the warmest, coziest hoods we know of, the Capilene Air is a fantastic next-to-skin piece. If you don’t plan to utilize the hood, it’s also sold in a standard crew-neck version that will save you $20, and the matching bottoms are equally cozy and light.
See the Men's Capilene Air Hoody  See the Women's Capilene Air Hoody


9. Ridge Merino Aspect Midweight Quarter Zip ($80)

Ridge Merino Aspect Midweight Quarter Zip (baselayer)Materials: 84% merino wool, 16% nylon
Category: Midweight
Weight: 8.3 oz.
What we like: Fantastic price for a high-quality merino baselayer.
What we don’t: Not the most breathable merino option here.

A family-run operation based out of California’s Eastern Sierra, Ridge Merino offers a small collection of high-quality yet affordable merino wool baselayers. The Aspect Midweight is the best all-rounder in their lineup—its 180g/m² thickness is just right for mild conditions or high-output activities, and it’s so soft and cozy that we can’t help but wear it around the house, too. What’s more, Ridge added a small dose of nylon to the construction, which helps a great deal with durability (we’ve also tested their 100%-merino heavyweight Inversion and found it much more vulnerable to forming holes). To top it all off, the Aspect Quarter Zip is just $80 (the crew is $75), making it one of the most affordable merino wool baselayers on the market.

Along with using a really high-quality wool blend, Ridge Merino has also done a great job paying attention to the finer details: The Aspect features well-designed thumb loops that disappear into the cuffs, flatlocked seams for a sleek appearance, and a long cut that doesn’t ride up. What you don’t get is any added ventilation or breathability measures (aside from the zip neck), which cross-country skiers, winter runners, and other endurance or uphill athletes will appreciate (the Smartwool Intraknit and Odlo below are great alternatives). But added up, we’re very impressed with the Ridge Merino Aspect, which offers a slight step up from Smartwool’s Classic All-Season above in terms of warmth. Finally, it’s worth noting that it also comes in a high neck version (akin to a turtleneck) for women, which offers an extra dose of coziness. Editor’s note: The Ridge Merino Aspect is low on stock at the time of publishing, but we expect to see renewed inventory this fall.
See the Men's Aspect Midweight Quarter Zip  See the Women's Aspect Midweight Quarter Zip


10. Icebreaker 200 Oasis Crew ($105)

Icebreaker Oasis 200 crew baselayerMaterial: 100% merino wool
Category: Midweight
Weight: 11.8 oz.
What we like: Softer against the skin than Smartwool.
What we don’t: Slim fit and dense weave lags behind in breathability.

The Oasis Crew from Icebreaker is as versatile as any baselayer on this list. It’s made from 100% merino wool, is super soft, and has a performance fit that works well for skiing and cool-weather hiking. And because of the clean styling and plethora of colorways and designs, you easily can wear it as a standalone piece.

If you’re considering the Oasis, it’s a head-to-head matchup with the Smartwool Classic Thermal above. Both models are made from 100% merino, and the prices are similar (the zip-neck version of the Oasis is also $115). Both are comfortable, wick moisture well, and don’t trap odor like synthetics. That said, we give the slight edge to the Smartwool because the dense weave of the Icebreaker’s fabric doesn’t release hot air quite as efficiently. Despite having a lighter fabric weight (200 vs. 250g/m²), it can start to feel muggy when you’re working up a sweat. On the flip side, the Icebreaker wins out in next-to-skin softness, making it the better option for those that prioritize comfort above all else. And if you’re looking to level up in terms of warmth, consider Icebreaker’s 260 Tech ($125), a midweight version of the Oasis here.
See the Men's Icebreaker 200 Oasis  See the Women's Icebreaker 200 Oasis


11. Arc’teryx Rho LT Zip Neck ($125)

Arc'teryx Rho LT Zip Neck men's baselayerMaterials: 84% polyester, 16% elastane
Category: Midweight
Weight: 7.9 oz.
What we like: A quality synthetic baselayer for high-output activities.
What we don’t: Expensive; too warm for shoulder-season use.

Arc’teryx places a premium on high performance, which shows in their baselayer collection. Their midweight Rho LT Zip Neck is tailor-made for regulating body temperature in cold weather, whether you’re moving or standing still. The key here is Arc’teryx’s Torrent material, which feels like a step up from most polyester/elastane blends: It doesn’t stretch out of shape or retain odor, is perfectly supple and stretchy, and features a cozy brushed liner for excellent comfort and moisture management. Combined with a moderately trim fit that effectively traps warmth and makes it easy to layer overtop (the smooth exterior certainly helps), the Rho LT Zip Neck stands out as a thoughtfully built baselayer for winter activities like snowshoeing, hiking, and skiing.

Arc’teryx recommends the Rho LT for low-output activities in cold weather, but we’ve found it to be a surprisingly good breather for its warmth and weight. In fact, it was one of our go-to baselayers last winter for outdoor training, including road running and nordic skiing (we usually paired it with a lightweight softshell or windbreaker). But it’s not the best shoulder-season piece: As temperatures rose above freezing, we started to reach for thinner layers. As with most Arc’teryx products, the Rho LT Zip Neck doesn’t come cheap—$125 is a high price to pay for a synthetic baselayer—but they pull off the non-merino build better than most. For those who prefer more neck and head protection, the Rho LT is also available in a hooded version (the Rho LT Hoody) for $135. 
See the Men's Arc'teryx Rho LT Zip Neck  See the Women's Arc'teryx Rho Lightweight


12. REI Co-op Merino 185 Half-Zip ($90)

REI Co-op Merino 185 Long-Sleeve Half-Zip baselayerMaterial: 100% merino wool
Category: Midweight
What we like: A soft, stretchy, and well-made baselayer. 
What we don’t: Pricey for an REI product. 

Of all of REI Co-op’s in-house products, their merino baselayer is one of our favorites. It’s right on the same playing field as heavy hitters like Smartwool and Icebreaker, which is quite a feat given that those companies specialize in wool layering pieces. The Co-op recently updated their Merino Midweight Half-Zip design (200g/m²) to the Merino 185. It drops a little warmth with the thinner construction, but like its predecessor, the Merino 185 is soft, has a good amount of stretch, and wicks moisture effectively. And most importantly, it can handle everything from backpacking to cross-country skiing with ease.

Unlike many REI products, the Merino 185 Half-Zip doesn’t come at much of a discount, which is why we have it ranked here. The 185g/m² thickness is a noticeable step down in warmth from Icebreaker's popular 200 Oasis Crew but only $15 less, although you do get a front zip and higher collar on the REI. And for $25 more, you can get the legendary Smartwool Classic Thermal above, our top pick, which is slightly thicker and much warmer at 250g/m². We really like the REI and have had nothing but positive experiences with it thus far, but we’re not ready to dethrone the Smartwool just yet.
See the Men's REI Merino 185 Half-Zip  See the Women's REI Merino 185 Half-Zip


13. Odlo Performance Wool Warm Long Sleeve ($100)

Odlo Natural %2B Kinship Warm Long-Sleeve (turquoise)Materials: 52% merino, 29% polyester, 13% polyamide, 6% elastane
Category: Lightweight
Weight: 6.6 oz. 
What we like: Snug fit and great ventilation is ideal for active pursuits.
What we don’t: Not our first choice for resort skiing.

Odlo emerges from Norway with a lineup of thoughtful baselayers built for a range of activities and conditions. Our go-to for ski touring last winter, their Performance Wool Warm Long Sleeve blends merino wool with stretchy polyester, polyamide, and elastane for a long sleeve that excels in mild temperatures and while building heat. You get great breathability thanks to the shirt’s mapped ventilation zones, and we’ve found moisture wicking to be top-notch. Further, the performance-oriented fit is snug yet stretchy, and Odlo even eliminated seams along the shoulders for comfort while carrying a pack. To top it off, build quality is excellent, with both our top and bottoms holding up great after a couple months of frequent use. 

While we love the Performance Wool Warm Long Sleeve for high-output activities like ski touring and cross-country skiing, it’s less appealing as a resort baselayer. You can go a lot warmer with a midweight option like the Smartwool Classic Thermal above, and many will appreciate a more relaxed fit for lunch or après at the lodge. On the other hand, we're big fans of the stylish patterning along the torso and sleeves (and it’s also available in a half-zip version). Added up, we really like what Odlo has done with the Performance Wool Warm Long Sleeve, making it one of our favorite merino blends here. For adventuring in mild conditions, Odlo also makes the Performance Wool Light, which combines soft Tencel fibers (sustainably sourced from wood) and wool to create a thin and breathable—yet still durable—baselayer.
See the Men's Odlo Performance Wool Warm  See the Women's Odlo Performance Wool Warm


14. Black Diamond Solution 150 Merino Crew ($135)

Black Diamond Solution 150 baselayer crew (black)Materials: 78% merino, 22% polyester
Category: Lightweight
Weight: 6.7 oz.
What we like: The benefits of merino, plus moisture wicking and durability.
What we don’t: Expensive for a lightweight baselayer.

Black Diamond’s Solution Wool lineup made waves at its debut, namely for its innovative NuYarn technology. Many manufacturers weave fibers together with merino to reap the benefits of both, but NuYarn takes it to the next level, wrapping nylon with extra-fine merino fibers for a thread that exudes technical performance down to its literal core. The end result is impressive: Compared to a baselayer like the Smartwool Classic All-Season above, the Solution 150 is noticeably more durable and dries out very quickly when wet (great news for those who are prone to working up a sweat). 

After wearing the Solution 150 for six days straight while hiking in Patagonia, we were impressed with how well it held its shape and resisted odor. Under a loaded backpack, the offset shoulder stitching was comfortable and mitigated pressure points, and the thumb loops are sleek and well constructed. In fact, our biggest gripe with the Solution 150 is its price—at $135, it’s $50 more than Smartwool’s comparable baselayer top (the Classic All-Season Merino). But cost aside, the Solution 150 has solid all-around performance and will last longer than most merino baselayers.
See the Men's BD Solution 150 Merino  See the Women's BD Solution 150 Merino


15. Ortovox 185 Rock'N'Wool Long Sleeve ($110)

Ortovox 185 Merino Rock'n'wool Long-Sleeve Base Layer Top__Material: 100% merino wool
Category: Light/midweight
Weight: 6.9 oz.
What we like: Great styling and super-soft hand feel.
What we don’t: Expensive and lacks durability.

We’ll start with the basics: The Ortovox 185 Merino long-sleeve crew is a standard merino baselayer. Much like the chart-topping Smartwool, it’s made with 100% wool, which means you get uncompromised odor resistance, great temperature regulation, and a cozy, soft touch. At 185 g/m², it’s lighter than the Smartwool Classic Thermal, meaning it’s more suitable for shoulder-season or high-output activities. That said, the thin fabric, paired with the fact that it’s not blended with a synthetic material, does make us concerned about the Ortovox’s durability (even Smartwool’s 150-weight shirt features a merino/nylon blend).

But here is where the Rock’N’Wool stands out: First, the Ortovox Wool Promise ensures that their product comes from ethical and certified sheep farms. And second, we just can’t get enough of the styling on the Rock’N’Wool—if you want a merino baselayer with some flair, the multi-colored designs really stand out in the conservative and largely bland baselayer market. For a versatile, breathable next-to-skin layer that can take you straight from skin track to après, the Ortovox 185 is an eye-catching but still very capable choice.
See the Men's Ortovox 185 Rock'N'Wool  See the Women's Ortovox 185 Rock'N'Wool


16. Ibex Woolies Tech Long Sleeve Crew ($115)

Ibex Woolies Tech Long Sleeve Crew baselayerMaterials: 81% merino wool, 12% nylon, 7% elastane
Category: Light/midweight
Weight: 7.4 oz.
What we like: A solid all-around option from a premium wool specialist.
What we don’t: Less comfortable than all-wool designs and not a great value.

For those unfamiliar, Ibex is a Colorado-based merino wool brand that specializes in performance apparel for outdoor use—from hiking and running to snow sports and travel. We especially like the Woolies Tech Long Sleeve Crew, which is part of their flagship Woolies collection and utilizes a functional mix of merino (81%) with added nylon and elastane for a boost in durability and stretch. The fabric has a premium feel to it—it’s soft, stretchy, and feels great against the skin—and all of the smaller details are similarly well sorted, including flatlock seams to minimize chafing, a nice selection of classy colorways, and handy thumb holes for layering overtop. A final highlight: All of Ibex’s wool is sourced from farms in Australia and New Zealand that are checked regularly to ensure the sheep are being treated humanely. 

It's worth noting that we’ve been testing the 1/4-zip version of the Woolies Tech, which retails for $135 and tacks on a zipper for easily regulating temperature (you can unzip to cool off when working hard). We included the Crew here given its nearly identical construction and feature set for $20 less, but neither model is a standout value. For the same price, the top-ranked Smartwool Classic Thermal above has a slightly softer all-wool construction and includes a quarter-length zipper to regulate heat. Alternatively, for $30 less, you can pick up their Classic All-Season above, which uses a similar mix of merino and nylon (88% and 12%, respectively) but in a slightly thinner design (150g/m² vs. the Ibex’s 180g/m²). But price aside, the Woolies Tech stands out as a solid all-around option from a proven wool specialist, earning it a spot on our list this year.
See the Men's Ibex Woolies Tech  See the Women's Ibex Woolies Tech


17. REI Co-op Lightweight Base Layer Crew ($40)

REI Co-op Lightweight Base Layer Crew_Materials: 92% polyester, 8% spandex
Category: Lightweight
Weight: 6.5 oz.
What we like: Simple yet functional.
What we don’t: Not super comfortable or a high performer.

In terms of bang for your buck, it’s hard to top REI baselayers. For $40, the Lightweight Crew offers most of the performance of the more expensive options above in a simple yet functional design. Additionally, REI honed things in even further with 8% spandex in the construction, which gives it a nice, stretchy feel. Paired with the matching bottoms, you can pick up a full long underwear set for $80 ($10 cheaper than just a merino top from Smartwool).

What are the downsides of the REI? We’ve found the lightweight model works well for mild resort skiing days, hiking, and casual use, but you may not be warm enough in frigid temperatures. Of note, REI does offer a warmer version (the Midweight Long Sleeve) for $55. And although the Co-op’s fabric is comfortably silky, it can’t compete with merino or even Patagonia’s Capilene in terms of softness and comfort (and it’s even more prone to holding in body odor). These issues aside, the REI Lightweight (or Midweight) Crew is a good way to kit yourself out this winter on a budget.
See the Men's REI Lightweight Crew  See the Women's REI Lightweight Crew


18. Woolx Glacier Long Sleeve Crew ($150)

Woolx Glacier men's baselayerMaterial: 100% merino wool
Category: Heavyweight
Weight: 1 lb. 1.6 oz.
What we like: Very warm and soft; a great value for an all-merino baselayer.
What we don’t: Because of the thickness and cut, it’s not ideal for high-output activities.

Woolx is a small New York-based company that doesn’t get the hype of a Smartwool or Icebreaker, but their thick Glacier is a cozy and well-built heavyweight baselayer. Made with 100% merino wool, this piece is much warmer and more substantial than the midweight and lightweight options on the list. And because it’s merino, it’s still soft against the skin and breathes well. We’ve used the Glacier for everything from skiing and snowshoeing to casual use and have come away very impressed.

Stacked up against our top heavyweight pick, the Patagonia R1 Air Zip-Neck, the Woolx Glacier Long Sleeve Crew is noticeably thicker and warmer. Unfortunately, Patagonia doesn’t provide a g/m² spec for the R1, but the Glacier’s 400g/m² is unmistakably best suited for the coldest winter days, which may be good or bad depending on your intended use. It also costs an additional $30 more than the Patagonia, doesn’t come in a women’s version, and has a decidedly relaxed fit that leaves more room for air to move around. For working hard in frigid temps, we give the edge to the R1 Air, but the Woolx has its place as a premium wool alternative for less intensive activities. For milder temperatures, check out Woolx’s popular Essential Tee, which features lightweight (150 g/m²) merino wool.
See the Men's Woolx Glacier


Baselayer Comparison Table

Baselayer Price Materials Category Weight g/m²
Smartwool Classic Thermal $115 100% merino wool Midweight 10 oz. 250g/m²
Patagonia Capilene Midweight $79 100% polyester Light/mid 6.2 oz. 147g/m²
Helly Hansen Lifa Stripe Crew $45 100% polypropylene Lightweight 5.1 oz. 125g/m²
Outdoor Research Echo Hoodie $75 100% polyester Lightweight  4 oz. Unavail.
Patagonia R1 Air Zip-Neck $119 100% polyester Heavyweight 10.2 oz. Unavail.
NW Alpine Black Spider Hoody $135 92% polyester, 8% spandex Midweight 11 oz. 194g/m²
Smartwool Classic All-Season $90 88% merino wool, 12% nylon Lightweight 6 oz. 150g/m²
Patagonia Capilene Air Hoody $159 51% merino wool, 49% polyester Midweight 6.9 oz. 190g/m²
Ridge Merino Aspect Midweight $80 84% merino wool, 16% nylon Midweight 8.3 oz. 180g/m²
Icebreaker 200 Oasis Crew $105 100% merino wool Midweight 11.8 oz. 200g/m²
Arc’teryx Rho LT Zip Neck $125 84% polyester, 16% elastane Midweight 7.9 oz. 190g/m²
REI Co-op Merino 185 Half-Zip $90 100% merino wool Midweight Unavailable 185g/m²
Odlo Performance Wool Warm $100 52% merino, 29% polyester, 13% polyamide, 6% elastane Lightweight 6.6 oz. Unavail.
Black Diamond Solution 150 $135 78% merino, 22% polyester Lightweight 6.7 oz. 150g/m²
Ortovox Rock'N'Wool LS $110 100% merino wool Light/mid 6.9 oz. 185g/m²
Ibex Woolies Tech LS Crew $115 81% merino, 12% nylon, 7% elastane Light/mid 7.4 oz. 180g/m²
REI Co-op Lightweight Crew $40 92% polyester, 8% spandex Lightweight 6.5 oz. Unavail.
Woolx Glacier LS Crew $150 100% merino wool Heavyweight 1 lb. 1.6 oz. 400g/m²


Baselayer Buying Advice

Baselayer Materials

Merino Wool
Merino wool is our favorite baselayer material for winter use: It’s ultra soft and incredibly warm for the weight, offers great temperature regulation, and resists odor far better than synthetic materials. For a warm and cozy next-to-skin layer that doesn’t clam up, it’s a great choice. However, merino wool baselayers are less durable than the synthetic competition, especially thin varieties or those that aren’t blended with other materials like polyester or nylon (for example, the Smartwool Classic All-Season is 88% merino wool and 12% nylon). They’re also too warm for mild conditions and intense activity like ski touring, running, and nordic skiing, and absorb sweat more than synthetics (which isn’t great news once you cool down). But for mellow days out or if you really prefer the feel of natural material, merino has a lot to offer. For more information about its pros and cons, check out our article: Merino Wool: Is It Worth It?

Backpacking beside lake in baselayer
Backpacking in the 100%-merino Smartwool Classic Thermal

Synthetic materials like nylon and polyester are a cost-effective alternative to merino, and excel in terms of moisture wicking and durability. For shoulder-season conditions, high-output activities, or use as an outer layer (as in the case of a layer like the NW Alpine Spider Hoody), they’re our first choice. The largest downside to synthetics is stink build-up; despite efforts from manufacturers, odor-resistant polyesters and nylons still can’t compete with the natural benefits of merino (although they are improving). In addition, synthetics don’t provide as much warmth for the weight, and as such are not our first choice in truly frigid conditions or for low-intensity activity. It’s also worth noting that they range a great deal in terms of quality: The Arc’teryx Rho LT uses a really high-end polyester material, while the Patagonia Capilene series is more prone to pilling and snagging.

It’s not quite as simple as deciding between an all-merino or all-synthetic baselayer. Some brands use blends that aim to offer the comfort and performance of merino wool alongside the durability and moisture-wicking of polyester/nylon. We often see this in lightweight varieties: Black Diamond's NuYarn (as seen in the lightweight Solution 150) wraps merino fibers around a nylon core, and then weaves this manufactured thread together with polyester. It’s worth being cautious with 100% merino—unless the fabric weight is around 200 grams per square meter (or more), pure merino wool will form holes fairly quickly.

Baselayer (hiking in the Ibex Woolies Tech)
Blends offer the cozy warmth of merino alongside the breathability and durability of synthetics

Important Strengths and Weaknesses

The breathability of a baselayer is dependent on a number of factors, including the type and quality of the fabric, thickness, and openness of the weave. In general, lightweight merino wool and synthetic baselayers (like the Outdoor Research Echo) offer better breathability than heavier-weight offerings. But between the two materials, synthetics are by far the more breathable choice: While merino does a great job pulling moisture away from your skin, it has a tendency to hold on to it. We’ve also found that merino is simply too warm for most intense activities. As a result, synthetic baselayers are our go-to for mild conditions or when we anticipate building a sweat (think ski touring, nordic skiing, and running). And it’s worth mentioning that there are a few merino offerings that we’ve found to be serviceable, particularly those with mesh panels in high-heat areas (like the Smartwool Intraknit Active or Icebreaker 125 ZoneKnit). 

Polyester: Excellent
Blends: Very good
Merino: Good

Bootpacking with skis on back wearing baselayer and midlayer
Breathability is important for high-output activities

Odor Prevention
Merino wool excels at pulling moisture away from your skin, and less sweat build up means less stink build up. If you’re taking an extended backcountry trip and don’t want to carry multiple baselayers or rinse them each night, merino is the way to go. Some synthetics do fine for odor prevention, provided you aren’t working up a huge sweat. For example, we’ve hiked for extended periods in Patagonia’s Capilene Midweight in cool weather and have been impressed with its odor resistance. But nothing beats merino in keeping you dry and stink free.

Merino: Very good
Blends: Good
Polyester: Not good

Baselayers (Black Diamond Solution Merino 150)
Layering with the Black Diamond Solution 150 merino baselayer

Here is where the tide changes: Merino is super soft but prone to developing small holes over time that eventually hamper the performance of the product, whereas synthetics should last for multiple seasons. To put this in perspective, we usually get a season or two out of a standard lightweight merino baselayer, even from the top brands and by following their washing instructions (cold water and line dry). Admittedly, these shirts get a lot of use, but that’s still a very short lifespan. But with synthetics, one or two seasons would be on the short end of the spectrum and we would hope for more like three or four.

Some companies are blending wool and synthetics to increase the strength of the baselayer without compromising next-to-skin comfort, which is a good idea in our opinion. We haven’t noticed much of a drop in terms of comfort or performance, but merino/synthetic blends are a step up in durability. Even so, if we’re wearing a baselayer without anything overtop, we’ll always opt for a fully synthetic piece such as the NW Alpine Black Spider Hoody.

Polyester: Excellent
Blends: Very good
Merino: Not good

Baselayers (climbing in the NW Alpine Spider Hoody)
Climbing in the ultra-durable NW Alpine Black Spider Hoody

Out of all the fabrics we’ve mentioned, merino has the best heat-trapping properties. In terms of the amount of warmth you get for the weight, it far exceeds polyester or nylon. However, if you plan to wear your baselayer as an outer layer, the roles are reversed: Merino doesn’t do much to block wind, while some polyester fabrics (such as Patagonia's R1 Air Zip-Neck) are so tightly woven that they have the ability to resist light gusts. And keep in mind that warmth is directly related to the thickness of the material too, which we discuss in the Insulation Weight section below. 

Merino: Excellent
Blends: Very good
Polyester: Good

Layering a synthetic jacket over a baselayer while skiing
Merino wool offers excellent warmth for winter activities

Baselayer Categories: Insulation Weight 

Logically, lightweight baselayers are the best breathers but do the least toward keeping you warm, making them ideal for spring skiing, bluebird days, and high-output activities such as nordic skiing and cold-weather running. That said, even thin merino wool baselayers can be very warm for their weight, so you’ll want to keep this in mind depending on your use (we found the 180-g Smartwool Intraknit Thermal to be much too warm for ski touring). What’s more, the thinner the merino, the less durable it becomes; for this reason, most lightweight baselayers are made of polyester. Our favorite lightweight offering is the Outdoor Research Echo Hoodie, which we’ll even wear as a sun protection shirt during the summer months. If you’re looking for mid-winter warmth, it’s worth bumping up to a midweight baselayer.

For the widest variety of conditions, a midweight baselayer makes the most sense. It will provide the warmth you need yet still be breathable enough for physical exertion, especially when made with high-quality merino or polyester. Midweight baselayers are the most popular choice for downhill skiers: They’re plenty warm for the lift ride up but you are unlikely to overheat on the descent. They are less popular than lightweight baselayers for hiking or ski touring in moderate conditions as the extra warmth corresponds with a drop in the fabric’s ability to regulate temperatures (even merino can get too hot in warm temperatures). But in cool spring and fall conditions, a midweight baselayer can perform great as an outer layer and is the ideal next-to-skin layer for resort skiing on cold days.

Smartwool Merino 150 crew baselayer
A midweight baselayer is a safe bet for most shoulder seasons

Heavyweight baselayers are specialty items for cold temperatures or if you’ll be relatively sedentary. The extra thickness inhibits breathability and it’s easy to start sweating even on short walks. Keep in mind that you don’t need all of your insulation from a single article of clothing, and as a result, you can always add warmer layers on top of a light or midweight baselayer. But for winter mountaineering, extreme cold, or low-output activities around camp, a heavyweight baselayer can be the height of coziness. If you do go this route, we love the Woolx Glacier Long Sleeve Crew, which is a 400g/m² all-merino baselayer that still breathes decently well. Patagonia’s Thermal Weight Capilene can get swampy unless it’s very cold.

Baselayer (sitting in tent in Patagonia R1 Air)
Patagonia's heavyweight R1 Air is a great match for low-output use in the cold

Crew Neck vs. Quarter or Half Zips

Nearly every baselayer on the market is made in a number of styles, including long-sleeve crew and half/quarter-length zippered shirts. Many folks opt for a crewneck style, but there are a number of reasons to think about a zippered shirt. One upside is the ability to adapt to changing weather conditions. Zip up for added warmth at the start of the climb, and unzip as you work up a sweat. And if you want to remove the shirt altogether, it’s nice not having to take off your helmet to do so. Furthermore, the extra coverage you get with the raised collar is a nice boost in warmth, and we’ve even found that quarter or half-zip long sleeves have a decent look for around town. The downside is the collars can flop around if you unzip the shirts while running, and having a zipper on your next-to-skin layer isn’t as comfortable as the cleaner crew style.

Baselayer (Smartwool Merino 250 zip neck)
Zip-neck baselayers allow you to regulate temperature better than crew styles


For optimal performance, baselayers need to have a snug fit. This helps the fabrics draw moisture away from your skin most efficiently. Some folks like wearing their baselayers for casual use, and that’s when a dedicated performance product like Odlo Performance Wool Warm Long Sleeve is less useful. The shirt conforms to your body like a performance piece should, but it’s far too tight to wear anywhere else. A product like the REI Co-op Merino 185 Half-Zip is on the opposite end of the spectrum, with a roomier fit that sacrifices a little in moisture wicking and breathability. But it’s a great choice for those that prefer a dual use baselayer/casual shirt. In the end, your decision is a personal one, and we recommend looking at fit based on intended use and preferences on style.

Baselayer (Odlo Performance Wool Warm standing at ski hill)
Odlo's Performance Wool Warm has a next-to-skin fit

Key Baselayer Features

Baselayers can range from simple, featureless crew tops like the Patagonia Capilene Midweight Crew to hooded half-zips with a chest pocket (the NW Alpine Black Spider Hoody, for example). If you know you’ll be layering a mid or outer layer over your baselayer, the simpler the better. However, those who wear their baselayer as an outer layer will appreciate zip pockets and thumb loops. And climbers and skiers will benefit from a tight hood or balaclava that fits under their helmet, like what you get with the Patagonia Capilene Air Hoody. Furthermore, some baselayers even have the capability of blocking sun rays (measured by the UPF rating). As usual, it will help to identify what you’ll be using your baselayer for before determining what features you need.

Baselayer (thumb strap)
Thumb straps are handy for keeping sleeves in place


The focus on sustainability has been increasing in the outdoor industry over the past several years, and baselayers are no exception. In this category, there currently are two key trends: responsibly sourced wool and the use of recycled synthetic materials. The former indicates that sheep were treated humanely and in accordance with strict animal welfare and environmental standards (there are a number of certifications, including the Responsible Wool Standard and ZQ-certified wool). We’ve also begun to see more companies utilizing recycled materials, which cuts down on fossil fuel consumption and reduces the amount of plastics being produced overall (Patagonia's Capilene Midweight is made from 100%-recycled polyester). All in all, we appreciate these efforts and are eager to see more brands come on board.

What About Baselayer Bottoms?

Most baselayers on this list have a matching bottom with the same construction and a similar or identical price. For organization sake, we list the tops here as they are more popular, but the bottoms are readily available and share the same pros and cons. In general though, maintaining a warm core will do much more for your entire body’s comfort than keeping your legs warm. But given that there’s no need to choose—and provided that almost nothing is cozier than a pair of long johns—we’re huge proponents of baselayer bottoms as well.

Baselayer pants underneath Arc'teryx Sentinel LT women's ski pant
Baselayer bottoms are especially important for winter activities

Layering Systems: Base, Mid, and Outer Layers

To get the most out of your technical clothing, it’s important think of everything as a system. Each piece relies on the layers around it to perform well. As an example, if you have a baselayer that wicks moisture well, but are wearing a fully rubber mid or outer layer, it won’t matter how nice of a merino fabric you have: You’ll still be wet and miserable. As such, take the time to put together mid and outer layers that are as high-performing as the baselayers listed above.

Baselayers have two primary functions: warmth and moisture wicking. Whether constructed with wool, polyester or nylon, or a blend, a baselayer is made to retain your body’s heat while transporting moisture away from the skin. And these two features work together—keeping the body dry will in turn lead to more warmth. Baselayers are worn beneath a midlayer or shell during the winter months, or as an outer layer during the fall and spring for activities like hiking, biking, and climbing. The thickness and material of your baselayer will have big impacts on warmth and breathability, so make sure to keep this mind when making a purchase. 

Baselayers (Patagonia Capilene Air underneath synthetic jacket)
Your baselayer is tasked with wicking moisture and trapping warmth

For high-output activities, such as hiking, backpacking and climbing, breathability is top priority. We recommend a fleece jacket or synthetic jacket for balancing warmth and ventilation. High performers include the Arc’teryx Atom LT and the R line of fleeces from Patagonia. If you only plan to grab your insulating layer during downtimes, such as hanging around camp after the sun goes down, consider a warm and super packable down jacket. Skiing is a similar story, and conditions will dictate the best midlayer for you. Options can range from a puffy down jacket to a light fleece.

Outer Layers
Outer layers are the most specialized part of the system, and their complex designs can get quite pricey. A waterproof, breathable, and packable rain jacket is needed for activities like climbing and hiking/backpacking. Winter conditions are much harsher, so durability takes precedence for ski jackets. Their designs offer more pockets for storing gear or personal effects and a longer fit to protect you from snow sneaking through. There are also hardshell jackets that blur the lines, mixing the weight of a rain jacket with the performance (and extra cost) of a ski jacket.
Back to Our Top Baselayer Picks  Back to Our Baselayer Comparison Table

Powered by Drupal

How to Layer for Backcountry Skiing

Backcountry skiing can be an incredibly rewarding way to spend your time outdoors—no crowds, untouched snow, and a skin-track workout to compliment your knee-deep powder turns...

Best Midlayers of 2023

In the typical three-layer ski clothing system, the midlayer is given the all-important insulating duties. As such, it is the one article of clothing you’re most likely to swap out depending on weather conditions. Is it bristling cold and dry...

Best Windbreaker Jackets of 2023

Let’s get right to the point: we love windbreaker jackets. In our opinion, a good windbreaker is the most versatile outdoor jacket money can buy. These small but mighty outerlayers pack a punch...

How to Choose Baselayers

A baselayer’s primary job is to keep you comfortable while wicking moisture as you sweat. Whether you’re climbing steep skin tracks in the backcountry, skiing lift-accessed terrain at the resort, or climbing and hiking in cool shoulder-season weather...

Best Synthetic Insulated Jackets of 2023

If you’re looking for a jacket that offers solid warmth at a good value, synthetic insulation is the way to go. You don’t get quite as high of a warmth-to-weight ratio as down, but synthetic jackets resist moisture, can breathe better, and are more...

Merino Wool: Is It Worth It?

Merino wool, the ultra soft fabric most commonly found in performance baselayers and socks, is one of the most sought-after materials in the outdoor gear world. But is it worth the hype? Below we...

Best Backcountry (Touring) Skis of 2023

Unlike their lift-assisted alpine cousins, backcountry skis have two jobs: getting you uphill efficiently while retaining enough power to make the downhill worth the effort (and fun). The good news is...

Best Ski Jackets of 2023

Choosing the right ski jacket is all about managing the conditions that you might encounter on the mountain. This depends on the specific kinds of skiing you enjoy most—skinning up a sunny ridgeline in the North Cascades is far different than bracing...