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The Best Base Layers for Women

The Smartwool 1/4 zip is a little thinner allowing it to layer a little easier than others. Here we add another layer of warmth during this super cold day at Mt. Baker in Washington state.
By Amber King ⋅ Senior Review Editor
Wednesday November 14, 2018
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In search of the best base layer top for women? We pawed through 60 possible contenders and selected 10 of the highest performers on the market. We adventured through the high deserts of Utah, over the high seas of Iceland, and into the Rocky Mountains. During our travels, we climbed mountains, took on foggy and rainy weather, and hiked uphill in all kinds of conditions, testing the grit and limit of each piece. In addition to these field tests, we performed in-lab tests to objectively test a few of the five different key metrics we used to rate each shirt. Using these tests and our experiences, we offer you assessments and advice on the best long underwear top options out there.


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Awards Editors' Choice Award Top Pick Award Top Pick Award Best Buy Award  
Price $99.95 at MooseJaw
Compare at 2 sellers
$129.00 at REI
Compare at 2 sellers
$125.00 at Backcountry
Compare at 3 sellers
$49.95 at REI$75.96 at Backcountry
Compare at 4 sellers
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Pros Wide range of thermoregulation, cute, super cozy, great fit, fantastic breathability, no odor fabricImmensely comfortable, quick to dry, lightweight, huge range of thermoregulation, no smellCozy fleece interior, easy to layer, warm, high quality performance, versatile, stash pocket, tight fitGreat value, fitted, cute patterns, quick to wick, good breathabilityNatural 100% Merino wool fibers, warm, soft, cute patterns, wide range of thermoregulation, odor resistant
Cons Lacks durability, absorbs waterLacks durability, expensive, harder to layerMore expensive, not super breathableNot super warm, stinky fabric over time, lacks durabilitySticky layering, poor durability
Bottom Line Our favorite base layer that offers the best thermoregulation and performance making it perfect for big days in the wilderness.Utilizing a knit-technology design this unique construction offers an unbeatable level of comfort and breathability.This high performance synthetic is a Top Pick for pretty much any adventure you dream up.This value winner provides a great range of thermoregulation for versatile all-year round use.Wear this top anywhere from the mountains to the coffee shop.
Rating Categories Merino 250 1/4 Zip Capilene Air Crew Rho LT Zip Midweight Base Layer Crew Merino 250 Crew
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Specs Merino 250 1/4 Zip Capilene Air Crew Rho LT Zip Midweight Base Layer Crew Merino 250 Crew
Material 100% Merino wool, 250 Midweight 51% merino wool/49% recycled polyester seamless zigzag knit comprised of 18.5-micron-gauge lofted wool Torrent (84% polyester / 16% elastane) 92% polyester / 8% spandex 100% Merino wool, 250 Midweight
Cuts avaliable 1/4 zip, crew, 1/2 zip hoody Crew, hoody (no zip) 1/4 zip neck Crew, 1/2 zip neck 1/4 zip, crew, 1/2 zip hoody
Smelly over time? No No Yes Yes No

Updated November 2018
In this rendition of our update, we take a close look at the impressive Patagonia Capilene Air that offers a high level of performance and breathability, earning it a Top Pick Award. The fabrics are so ridiculously soft and comfortable, it'll have you yearning for a cup of tea next to a cozy fire…a perfect way to start the winter season.

Best Overall Women's Long Underwear Top


Smartwool Merino 250 1/4 Zip - Women's


Editors' Choice Award

$99.95
at MooseJaw
See It

Materials 100% Merino Wool | Style: Zip-neck
Incredibly comfortable
Thermoregulation range
Great wicking power
Comfortable fabrics
Heavy when wet
Not super durable

Wear this super comfy midweight top from the trail to your bed! The Smartwool Merino 250 ¼ Zip wins our Editors' Choice Award for its fantastic comfort and versatility. Loaded with 100% natural Merino wool fibers, it provides one of the most extensive ranges of thermoregulation tested. It functions well as a long underwear top and a wear-alone top in temperatures ranging from the double negative digits to highs of 70 degrees Fahrenheit. It outperformed every other shirt in this review because of its ability to keep us dry and comfortable when conditions went from warm to cold and wet to dry. The fabric wicks away moisture, dries quickly when on, and doesn't stink.

While the fabric is soft and cozy, the only thing that it truly lacks is durability and not the best for abrasive activities. Also, when it gets wet, it absorbs quite a bit of water. Aside from these caveats, it performs wonderfully in all conditions and will keep you warm and comfortable out in the wild.

Read review: Smartwool Merino 250 1/4 Zip - Women's

Best Bang for the Buck


REI Co-op Midweight Base Layer Crew - Women's


Best Buy Award

$49.95
at REI
See It

Materials: 92% Polyester, 8% Elastane | Style: Crew
Great price
Easy to layer
Stretchy and comfortable
Fast to dry
Smelly over time
Not super warm

Keeping tabs on your wallet? This 100% polyester midweight top costs only $50 retail, with deals for even less online! Our testers appreciate its smoother face-fabrics that made layering easy in addition to its stretchy fit. It dries quickly, and the fabrics are super soft to the touch. It's also pretty cute with a few options for style and cut.

The downside? While the thin material is more breathable, they are not super warm. Also, the fabric, unfortunately, pills and can stink over time. While these downsides exist, the reality is that it performs well and goes for a great price. An excellent option for wear in warm to cool weather.

Read review: REI Co-op Midweight Base Layer Crew - Women's

Top Pick for Versatility


Arc'teryx Rho LT Zip - Women's


Top Pick Award

$125.00
at Backcountry
See It

Materials: Torrent (84% polyester, 16% elastane) | Style: Fitted zip-neck
Cozy and warm
Fitted design that's easy to layer
Longer fit through arms and torso
Stash pocket
Ultra-durable and well-crafted
Lacks impeccable breathability
Expensive
Smelly over time

Seeking a technical option? This ultra-versatile and high performing top takes a win as a Top Pick! This 100% polyester baselayer is super durable, comfortable, and holds up in the crud. Our main tester has owned this shirt for over five years and chose to wear it for a plethora of activities ranging from backcountry splitboarding in Alaska to rafting the Grand Canyon. Through these experiences, we learned that this layer is warm, well-fitted, and thermo-regulates well for its weight. It's the most versatile product we've tested thus far.

While it has many pluses, we aren't too thrilled about the really high price tag. Nor do we like the fact that there is a slight pungent residual smell (even after using tech wash) that lingers in the fabric after a few years of use. Despite these minor details, we are still in love with this piece, and it will continue to travel the world with us.

Read review: Arc'teryx Rho LT Zip - Women's

Top Pick for Breathable Comfort


Patagonia Capilene Air Crew - Women's


Materials: 51% Merino Wool, 49% Recycled Polyester Style: Crew & Hoody
Ridiculously cozy
Super warm
Ultra breathable
Not durable
Not wind-resistant
Expensive

The Patagonia Capilene Air Crew features a 3-D knit design that stacks layer upon layer of comfort and warmth. No other contender currently uses this kind of technology, and we are tickled pink about it. The blend of merino wool and polyester offer both a high level of warmth and a ridiculous level of wicking power and breathability. Never have we encountered a shirt that can balance these two opposite metrics so well. Not only that, but the design is really cute, earning informal wear status while out on the town.

While we love this top, we don't love the high price or the lack of durability in the fibers. Even with the infusion of synthetic fibers, it snags and catches easily on branches and abrasive surfaces if worn on its own. Also, it's not very wind-resistant (as a stand-alone top) and doesn't layer super well underneath other 'grabbier' insulated layers. Aside from that, it provides an awe-inspiring balance of warmth and breathability that earns it a solid Top Pick.

Read review: Patagonia Capilene Air Crew - Women's


Analysis and Test Results


A base layer top is an integral part of any women's outdoor wardrobe. This piece sits closest to the skin, wicks away moisture and ultimately will keep you warm and comfortable whether you're tackling a high summit or just out walking the dog on a cold day. During this review, we took each shirt on a plethora of adventures ranging from sailing adventures on the gnarly North Sea to climbing in Colorado. While wearing each shirt, we were able to rate each product on six key metrics that include; warmth, breathability, comfort & fit, layering ability, drying speed, and durability. Using this information, you can find the best long underwear top for your upcoming adventures.

The synthetic Rho LT Zip wins our Top Pick for versatility for its great performance in an array of conditions.
The synthetic Rho LT Zip wins our Top Pick for versatility for its great performance in an array of conditions.

Value


Wondering which top offers the best performance relative to its price? While the MSRP doesn't factor into our scoring metrics, we know just how important the performance received per dollar spent is. Typically, the largest trade-off in this category lies in the materials used. Merino wool tends to cost manufacturers more money than synthetic fabrics, and this higher price is passed on to the consumer. The two lowest-priced models in this review are synthetic tops. Crew tops almost always cost less than zip and hooded tops, so if you don't need those features, you can save some cash. Lastly, base layer tops often get color updates at least once a year. When that happens, it's a great time to snag the older colors at a friendly discount, making those pricey merino wool models more attainable.


Warmth


When choosing a long underwear top, warmth is one of the most important factors to consider. A top that keeps you warm, especially in cool to cold weather, will allow you to adventure without having to stop and warm yourself. When considering the warmth of a shirt, there are two main factors to consider that include; the fabric weight and wicking ability.

Long underwear tops are rated for warmth based on their fabric weight. A high weight generally can be interpreted as thicker. A heavy or expeditionary weight typically equates to more warmth while a lightweight option is not as warm and better for warmer temperatures. The fabric's wicking abilities in a layered system is another essential aspect to consider. The fabric must wick sweat away from your skin. If the material is unable to do this, sweat will eventually cool down, which inevitably leads to a drop in your core temperature.


Merino Wool

After hiking, skiing, and climbing with each product, we have noted that Merino wool is warmer than tops of synthetic construction. The Icebreaker Tech 260 Midweight is the warmest base layer tested with 260g of 100% Merino wool fibers. The shirt is heavier in weight and kept us warm while the Arctic winds blasted us during the Polar Vortex on the East Coast this last year. It, like the Smartwool Merino 250 ¼ Zip, kept us warm in a layered system when temperatures got well into the double negatives.

Freezing our buns off on a negative 20-degree day  we test the capabilities of the super warm Icebreaker 260 in a layered system while running five miles through the pavement jungles of Mississauga  Ontario. Despite the frozen eye-lashes  we were still smiling!
Freezing our buns off on a negative 20-degree day, we test the capabilities of the super warm Icebreaker 260 in a layered system while running five miles through the pavement jungles of Mississauga, Ontario. Despite the frozen eye-lashes, we were still smiling!

That said, the Merino 250 ¼ Zip wasn't as warm on its own because of its thinner construction and loosely woven face fabric that lost heat more quickly. We did, however, like the functioning zip-neck that locks in warmth around the collar on super windy days. Another Merino wool contender that scored high in warmth is the WoolX Hannah for its longer fit, providing ample coverage. With just 230g of Merino wool, it is not as stacked as the Smartwool tops, but the face fabric is more tightly knit, locking in warmth better. All shirts did an excellent job at wicking away moisture for quick evaporation, except for the 240g Kari Traa Rose because of it's super tight-knit construction. While this provided ample warmth while sitting still, it had us shivering after sweating when we took a little break.

A surprising contender that is unique for its construction is the Patagonia Capilene Air that earned a high score for warmth. While this top is constructed of 51% merino wool and 49% recycled polyester, it provides a warmth that is almost as good as the Smartwool Merino 250 ¼ Zip. The fabric wicks amazingly well while the unique knit design that is stacked into layers provides fantastic warmth as a layered piece.

Synthetic Options

Polyester isn't as warm as Merino wool because it holds moisture in the fabric when worn. When trail running on a warm day, we went from warm to cold temperatures and noticed that polyester fabrics held more moisture, making us shiver when stopping for lunch. This is a weird observation as synthetic typically dry much faster (which we'll talk about later) when dried in the sun or a dryer. However, when worn against the skin, the material doesn't wick as well as Merino wool. We also think that the synthetic fibers don't generate as much heat.

Providing ample warmth in the high mountains of Alaska  we test the warmth of the Rho LT while splitboarding on this eight-mile tour over glaciers and corniced precipices.
Providing ample warmth in the high mountains of Alaska, we test the warmth of the Rho LT while splitboarding on this eight-mile tour over glaciers and corniced precipices.

While synthetics typically aren't as warm as Merino wool, some competitors have kept us as warm as both a base layer and as a wear-alone top. The Arc'teryx Rho LT Zip makes the top of the list with its 82% polyester (and Elastane) architecture that hugs the body. The interior is fleece-lined which generates even more heat. It wicks well and is one of the warmest options because of its wind-resistant face fabric that is super tightly knit, and it's super fitted design. The REI Co-op Midweight is our Best Buy winner that has 92% polyester (more than the Arc'teryx), but the thinner fabrics that aren't as wind-resistant, making it not as warm when worn on its own. It performs similarly to The North Face Warm, generating a decent amount of heat on the move. As mentioned above though, we found all these warmer synthetics are a little more prone to holding moisture (especially in a layered system) and thus, they didn't score as high. They are a great option if you need something that is durable and dries out quickly.

In this review we compared only midweight layers that are meant for warm to cool weather. If you plan on being in some of the coldest weather on Earth, a heavier weight might be necessary, whereas if you are going adventure when the sun's a-blazing, a lighter weight will do you well. All tops tested have a wide range of different weight categories. So if you want to beef up or slim down on warmth, choose the correct weight.

Breathability


Playing a key role in thermoregulation, breathability is how well the fabric allows heat to escape, providing venting capabilities in addition to less affinity for you to sweat on the trail. When worn in a layered system, breathability enables fabrics to move moisture from the skin to the exterior. If you have a less breathable mid-layer or jacket on, it could lock in unwanted moisture. So a breathable layered system is key. If you wear the shirt on its own, a breathable base layer is for aerobic activities like trail running, cross-country skiing, or riding bikes in the backcountry.


In our testing period, we wore each shirt without a layered system. Specifically, we took each trail running and hiked uphill for miles on end to see which ones allowed moisture to escape the most efficiently. In the end, we learned that the type of fabric and how closely the fabric is knit play vital roles in breathability. There was no exact correlation in our testing for Merino wool vs. synthetic materials other than the fact that Merino wool has a much more extensive range of thermoregulation, and is thus a more versatile fabric.

Here we take a training winter run after work with the Smartwool 1/4 Zip in a layered system. After the run where we transitioned from hot to cold  we felt comfortable. This Merino wool competitor thermoregulates well!
Here we take a training winter run after work with the Smartwool 1/4 Zip in a layered system. After the run where we transitioned from hot to cold, we felt comfortable. This Merino wool competitor thermoregulates well!

If you seek a top that will keep you cool while you sweat, the Patagonia Midweight Capilene is highly breathable. The 100% polyester fabric features a Polartec Power Grid architecture that allows ample air flow. The face fabric is also a little wind resistant making it our go-to for warm, windy day trail runs. It earns an almost perfect score in this metric and is an excellent option for active wear.

The new Patagonia Capilene Air is amazingly breathable  earning itself a Top Pick for its ability to keep you warm and offload heat efficiently.
The new Patagonia Capilene Air is amazingly breathable, earning itself a Top Pick for its ability to keep you warm and offload heat efficiently.

That said, the new Patagonia Capilene Air offers a surprisingly better level of airflow than even the Patagonia Capilene Crew. Even though the regular Capilene has a thinner construct, the Capilene Air offers a more porous fabric that does a way better job at wicking away moisture. As a result, you get a blast of air, and the material will keep you dry and comfortable, even while charging uphill.

A look at the fabric construct of the Patagonia Capilene that offers great breathability and ample air flow...it just doesn't wick as well as the Patagonia Capilene Air.
A look at the fabric construct of the Patagonia Capilene that offers great breathability and ample air flow...it just doesn't wick as well as the Patagonia Capilene Air.

The Smartwool Merino 250 ¼ Zip and 250 Crew fare well because of their loosely knit fabric design. We also like how the zip-neck version provides additional venting (and warmth) when needed. That said, neither breathe as well as the Capilene options.

Choose a lightweight material for any of these contenders for an airy and breathable experience.

Hiking uphill in Leavenworth  WA had us pushing the limits of breathability. While the North Face is super warm  it's not the best at breathing  hence hiking without a jacket or extra layer.
Hiking uphill in Leavenworth, WA had us pushing the limits of breathability. While the North Face is super warm, it's not the best at breathing, hence hiking without a jacket or extra layer.

Comfort & Fit


Ah, comfort…something every woman craves. What's better than wrapping yourself in fabrics that are as soft and smooth as Cashmere for everything from on the trail to at-home comfort? When testing this metric, we assessed each top to determine which had the coziest fabrics and the most versatile fit. In most cases, this testing was the easiest - lazing about watching movies, hanging out around the campfire, going out with friends, and seeing how fabrics feel after day four of constant wear with no wash. In general, we found that Merino wool tops with a fitted, stretchy design did best in this category. However, we are surprised by the Capilene Air that almost steals the show.


The Coziest Fabrics

The truly cozy and cuddle-worthy Smartwool 250 Midweight Crew is the most comfortable fabric in this review. It features 250g of natural 100% New Zealand merino wool, a bit of stretch, and thicker cuffs and hemlines. It feels glorious against the skin with no itch and simply sheer comfort. Another top-scorer for comfort is the Smartwool Merino 250 ¼ Zip, constructed of the same fabrics but featuring a zip-neck instead of a crew-cut collar. We like wearing the Smartwool 250 Crew each day because of its cute patterns and designs that could be worn on the trail and to work.

If you aren't prepared to buy it  don't try on the Capilene Air. It's very difficult to remove due to the happy-cozy-feels.
If you aren't prepared to buy it, don't try on the Capilene Air. It's very difficult to remove due to the happy-cozy-feels.

The Patagonia Capilene Air hosts super comfortable fabrics that offer a knit blend of merino wool and polyester. While it's not as comfortable as the Smartwool options, it is up there in performance earning a nine out of ten. It loses a point because of its high crew line that isn't the most comfortable. The fabric is stretchy, conforming to the body, but not as stretchy as the Smartwool options.

The Smartwool 250 Crew is comfortable for wear-all-day (and all-night).
The Smartwool 250 Crew is comfortable for wear-all-day (and all-night).

Other tops like the WoolX Hannah and Icebreaker 260 also have extremely cozy fabrics that will keep you wrapped up on cold days. Of the Merino wool options, the Kari Traa Rose H/Z proves to be the least comfortable 100% Merino wool top that some of our testers claimed to be scratchy when wet.

Fit

When looking at fit, we handed these shirts to a group of women that varied in height and weight. Some were tall while others were short, some had lots of curves, while others had none. In our evaluations, tops that had a stretchier and more voluminous fit proved to be the most versatile. We also looked at the relative lengths of the arms and torso to see which provided the best overall coverage. All shirts proved to be true to fit except the Kari Traa Rose H/Z that we recommend sizing up on.

Check out individual reviews to see the specific fit of each top. In these overviews, we provide more depth on the volume of the shirt and points of constriction or discomfort for different body types.

Long Arms and Torso?

Need a shirt with long arms and torso? Luckily we have a host of options. Of synthetic tops, the Arc'teryx Rho LT, a Top Pick for Versatility, features super stretchy fabrics that provide a next to the skin fit. The length of both the torso and arms are of some of the longest tested, working for both short and tall ladies, with and without a bust. Of Merino options, we found the WoolX Hannah to have the most extended fit. The fabric is somewhat stretchy and fits many of our testers well. In comparison, the Icebreaker 260 Midweight was a little shorter and more ideal for shorter testers in this review.

A look at the length of the Hannah  a great Merino wool option for those with longer arms and/or torso.
A look at the length of the Hannah, a great Merino wool option for those with longer arms and/or torso.

Other longer options: Smartwool Merino 250 1/4 Zip (Editors' Choice), REI Co-op Midweight Base Layer Crew (Best Buy award winner)

The Icebreaker Tech 260 is a great option for those with shorter arms and torso.
The Icebreaker Tech 260 is a great option for those with shorter arms and torso.

Shorter Styles: The North Face Warm, Kari Traa Rose (deep zip-neck), Icebreaker Tech 260

Layering Ability


A good base-layer can easily be worn next to the skin while layering a mid layer or jacket over it. While most long-underwear tops are presumably the "next-to-skin" layer, it is a bonus when you can wear a tank or tee underneath if you expect conditions to warm up. Not only that, but you want to make sure that you can throw layers on top and remove them without too much effort or static electricity that might cause your shirt to ride up while on the move. During our tests, we looked at the fabric make-up of each top and layered a fleece mid layer overtop to see how easy or hard it was to pull on the mid-layer. Long underwear tops that did best in this category feature a slippery face fabric, stretchier and thinner fabrics, and longer arms or thumb loops. Synthetic did better than Merino wool in this category.


Of all tops tested, the Arc'teryx RHO LT Zip proved to be the easiest to layer! The frictionless face fabric slides smoothly against even the fleeciest mid layers like the Patagonia R1 - Women's. The arms are long and can be held when layering to avoid frustrating layering situations like those experienced with more frictiony competitors like the Icebreaker 260 or WoolX Hannah. Other tops that do well with layering include the 100% polyester REI Co-op Midweight because of its frictionless face fabric and super stretchy design that hugs the body. While the North Face Warm does a great job not riding up while in action, the thicker fabric design is harder to layer than those with a thinner construct.

Every model tested fits fine under a spacious jacket.
Every model tested fits fine under a spacious jacket.

Of the Merino wool competitors, the Smartwool ¼ Zip and Kari Traa Rose are the easiest to layer, because of the next-to-skin fit and zip neck that offered a more streamlined layering experience. The Kari Traa Rose has a super tight-knit weave that makes sliding layers overtop easier than other Merino wool competitors. If you seek a Merino wool top that is easy to layer, consider a zip-neck option like those recommended above. Otherwise, go for a synthetic option that will leave you a little frustrated with little to no ride-up.

Layering the Hannah is a little harder than other synthetic competitors because of its stickier face fabrics. That said  we enjoy the long arms that allow us to pull them through the mid layer.
Layering the Hannah is a little harder than other synthetic competitors because of its stickier face fabrics. That said, we enjoy the long arms that allow us to pull them through the mid layer.

Synthetic base-layers proved to be easier to layer then Merino wool because of their slipperier face fabrics that don't grab mid-layers and pull.

Drying Speed


In need of a top that dries quickly? If you plan on adventuring in areas where you might encounter precipitation, you may require a quick-drying top. Wear it, take it off, and let it dry on a rock or in your laundry hamper for use the next day. To evaluate this metric, we went hiking in all sorts of precipitation and performed a few tests in the lab. We looked to see which (a) absorbed more water, and (b) dried the fastest in a controlled experiment. To do this, we weighed each shirt's dry weight. Then we washed each shirt for 30 minutes. Then we measured the wet weight. After that, we dried each shirt in the dryer at low temperature for ten-minute intervals, weighing each every ten minutes. The shirt that got back to its dry weight proved to be fastest to dry. Overall, we found breathable synthetics to perform better in these metrics.


Synthetics

As expected, the shirts that proved to be more impervious to water typically dried faster. The Patagonia Capilene Midweight proved to be the quickest to dry and absorbed the least amount of moisture (in part to its airy design). It dried in just 40 minutes and only absorbed 1.65 oz of water after washing for 30 minutes. This makes it a perfect option for those seeking a layer that will perform for multiple days on end. Other shirts that dried quickly and absorbed little water include the REI Co-op Midweight and The North Face Warm. BOTH absorbed only 2.15oz of water after washing. However, The North Face top performed a smidgen better, drying in just 50 minutes. The REI Co-op Midweight dried in 60 minutes, similar to the Arc'teryx Rho LT Zip. All these top performers feature a polyester-construct. Those with 100% polyester proved to be faster than those with a hybrid of elastane or spandex materials. All are great options for rainy weather.

This metric looks at the drying speed when not worn. Look at warmth if you want to figure out how quickly fabrics dry out when worn.

Merino Wool

While Merino wool competitors absorbed much more water, we were surprised at their great rate of drying. For example; the Icebreaker Tech 260 is the heaviest contender tester (when dry) but it managed to dry out at a similar time to all Merino wool tops tested (roughly 90 minutes). The only Merino wool top that took a little additional drying time is the Smartwool 250 Crew that took 100 minutes instead of 90 minutes. Of the Merino wool shirts tested, the Kari Traa proved to absorb the least amount of water (2.8oz), making it a great option for wet weather.

Merino wool stands out because it stays warm when wet. While these materials will absorb more water than synthetic competitors, it takes quite a bit of effort for the fabrics to absorb the water. The hydrophobic fibers do a better job at repelling water at first then synthetics. Synthetics, on the other hand, absorb water more readily and faster than merino wool. As a result, merino wool typically wicks better and dries at a faster rate. Take a look at the individual scores in this metric to see how all competitors did comparatively.

Durability


The best base layers out there should last you, although this category is notorious for not doing so. It shouldn't shrink, stretch out, pill, or fall apart after just a few months of use. Most importantly, a durable top shouldn't see holes after just a few times out on the trail. With prices ranging from $50 to $125, it's important to know that this shirt should last. To look at durability, we inspected shirts for fly aways, noted quality stitching, and looked for signs of wear and tear. We shimmied through canyons and bushwhacked through forests to see if the fabric snagged or tore.

We also wore heavy backpacks when heading up to the climbing crag or while camping to see if common areas of wear and tear became obvious after just a few months. We also looked to see if any garment shrunk or pilled after washing, and whether or not odors persisted. The best products showed little to no wear and tear, didn't smell, and proved to retain its performance. In our tests, we learned that while Merino wool doesn't stink like synthetic competitors, they were far less durable.


After many years of heavy use, we are super happy with the Arc'teryx Rho LT ¼ Zip. Arc'teryx is known for its bomber craftsmanship, and this product is no different. We have used and abused it while climbing, hiking, split-boarding, and more. After many long years of use, there are still no signs of stitching fly-aways or significant areas of wear and tear. Our only caveat is that the fabric retains a little smell. However, this is easily abolished by a tech-fabric cleanser use every six months.

Other durable synthetic products that showed a little pilling, but performed well overall include The North Face Warm for its thick fabrics and great durability. The REI Co-op Midweight and Patagonia Capilene also did well, but we observed a little pilling around the stitching seams. All these top scorers are of polyester design.

The Arc'teryx Rho LT scores a perfect ten for its renowned craftsmanship and wonderful performance!
The Arc'teryx Rho LT scores a perfect ten for its renowned craftsmanship and wonderful performance!

Of the Merino wool contenders, the Kari Traa Rose H/Z proved to be the most durable. Unlike the Smartwool and Capilene Air tops that proved to be some of the least durable in this review, the Kari Traa Rose features a tightly-knit face fabric that doesn't snag. The fibers are seemingly shorter and have proven to be more durable and a better option for those needing a top for high-friction sports like canyoneering, bushwacking, or rock climbing.

The Smartwool 250 Crew, on the other hand, proved to be the least durable of all. The fabric pills, the threads come undone, and we even observed a hole in the face fabric. As a result, we're disappointed with the durability of the Smartwool products. If you seek the most durable product out there, be sure to look into a synthetic option like the Arc'teryx Rho LT or the merino wool Kari Traa Rose H/Z.

The 250 Crew rubbed a hole through the fabric and experienced stitching flyaways throughout the garment. While this is a super comfortable and cozy shirt  it's not very durable.
The 250 Crew rubbed a hole through the fabric and experienced stitching flyaways throughout the garment. While this is a super comfortable and cozy shirt, it's not very durable.

In our observations over our testing period, we found that our merino wool layers need to be treated a more carefully than their synthetic competitors. We found that fibers in Merino wool products were more conducive to snags and the fabric pilled much easier than synthetics.

A Note on Odor
In all our tests, the synthetic shirts constructed of polyester typically smell more over time than those made of Merino wool. We also found that Merino wool tops could be worn for multiple excursions without washing before odor became an issue. Despite companies efforts to develop odor-resistant fabrics with a polyester design, we found that they inevitably smell over time, whereas Merino wool allows odors to wash away. Some of our testers prefer Merino wool for this one simple fact.

By wearing a base layer under a wind breaker  our main tester was comfortable and cozy while trail running over 100 miles in Peru. What do you demand from a great base layer top?
By wearing a base layer under a wind breaker, our main tester was comfortable and cozy while trail running over 100 miles in Peru. What do you demand from a great base layer top?

Conclusion


With so many options out there, it's difficult to determine the best base layer. However, it's important to figure out what you need for the function your shirt should provide. Consider the fabric type, style, and weight. Also, make sure you select a shirt that will fit you best. All contenders in this review work perfectly as apart of a layering system and can be worn on its own as well. Read through our Buying Advice article for more information on the different fabrics and cuts that are available to find the best option for you. Good luck in your search!


Amber King