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We put women's long underwear to the test, evaluating top models from Icebreaker, Patagonia, Smartwool, Arc'teryx, Ridge Merino, REI, Minus33, and more to find the very best
After 4 years of testing and multiple updates, we've selected the top performers for Women's Long Underwear.
Our team has tested over 50 pairs of the best long underwear for women over the last eight years, including the top 22 in our latest review. Each next-to-skin layer has seen loads of sweaty missions, from backcountry splitboarding to multi-pitch rock climbs to ultra trail runs — all in pursuit of finding the warmest, most breathable, and most comfortable pair of bottoms available. We test across North America throughout the colder half of the year, from the sandstone deserts of Utah to the high mountains of Alaska and California. After comparing these products side-by-side, our comprehensive review offers product insight and expert recommendations to help you find the perfect pair for your next winter adventure.
Efficient breathability, body-mapping technology for excellent thermoregulation, gusseted crotch for increased range of motion, stylish, great fit with high waist, soft and cozy, year-round use
Affordable, super warm, wool is super soft and odor free, loose fit is true to size, no durability issues or pilling
Affordable, high waist adds extra warmth, solid thermoregulation, very flattering fit, easy to layer, full coverage, odor-free
Lightweight, versatile, ample warmth, great fit and waistband, soft synthetic fabric, thigh pocket
Soft Merino fabric, fit is true to size, naturally odor-free
Durable, wide range of thermoregulation, comfortable, cute colors
Warm and cozy, body-mapped technology improves breathability, gusseted crotch for increased range of motion, feminine fit that's true to size, odor resistant
Very inexpensive, great fit and flattering high waistband, comfortable, breathable, easy to layer, competitive drying speed, lots of color options, thigh and waistband pockets
Super soft, great thermoregulation, stylish thick waistband, odor-free, ski and snowboard boot compatible
Smooth and silky fabric, easy to wear alone or when layered, cute and fitted style, affordable
Supersoft Polartec fabric, superior breathability, excellent warmth, great fit that enhances mobility, recycled fabric
Lightweight and thin design lacks warmth, fit is off
Very tight and unforgiving fit, waist slides down, not warm
Bottom Line
This outstanding 100% Merino wool design is the perfect layer for high-output cold-weather mountain pursuits
Though not the most breathable or fastest to dry, these bottoms prioritize warmth and comfort above all else
An excellent Merino Wool long underwear bottom that is versatile enough to be layered into your cold weather kit and stylish enough to be worn on its own
This lightweight synthetic long underwear bottom can do it all, thick enough to perform on its own or within your cold weather kit
A warm and cozy 100% Merino wool base layer that unfortunately lacks the durability and quality we'd expect from its expensive price tag
This is one of the most durable Merino wool contenders out there and the thermoregulation is top-notch
Designed with high-intensity winter sports in mind, these 100% Merino bottoms offer a ton of warmth, an emphasis on breathability, and ultimate comfort next to skin
Though these cute bottoms are not typical for a traditional long underwear bottom, they are perfect for those seeking a super cute stand-alone tight that offers a stylish and comfortable fit
Great wicking capabilities in a lightweight and stylish design, but with some questionable durability
This synthetic base layer option features a soft and stretchy polyester fabric that offers moderate levels of warmth and breathability for an affordable price
A high-performing long underwear bottom that traps a ton of warmth while releasing any excessive moisture created during cool-to-cold weather activity
These heavyweight 100% Merino wool bottoms offer superior warmth and comfort at a fraction of the cost
A synthetic long underwear bottom with an all-around impressive performance at a fair price
These high-performing midweight bottoms maximize warmth through strategic ventilation for optimal moisture management during cold weather conditions
Lightweight, breathable, and highly affordable, these tights unfortunately lack warmth and require constant adjustment due to the stretchy fabric and wide waistband
Unfortunately, you get what you pay for with these highly affordable bottoms that lack warmth, efficient breathability, and the durability you’d expect from a high-performing long underwear bottom that is built for optimal warmth during the coldest months
These affordable bottoms are very warm and comfortable thanks to their traditional, true-to-size basic fit, but they lack sufficient breathability and require more room in your ski bibs due to their thicker 320 g/m² midweight construction
These lightweight long underwear bottoms combine the wicking power of polyester with the odor-resistant performance of Merino wool, a perfect combination for anyone in motion
A Merino wool pant that's warm, comfortable, and offers a great value, though they do stretch out the longer you wear them
True to size with a thick waistband that layers well, sadly these bottoms are itchy, the design details aren't well executed, and breathability is poor
This lightweight 100% Merino wool design features super thin and breathable material that dries quickly and is easy to layer, however, the fit is off and they do not provide sufficient warmth
A lightweight option with superior breathability but a list of caveats
Body-mapping technology for increased range of motion
Ventilation panels upgrade breathability
High-waisted and feminine fit that's true to size without rigidity
Odor-free
REASONS TO AVOID
Expensive
Subject to durability issues
Lacks warmth for mellow cold weather activities
The Icebreaker 200 ZoneKnit Merino Leggings offer exceptional performance within a 100% Merino wool design. A tightly woven, 200 g/m² fabric and body-mapped ventilation panels in specific locations help these bottoms insulate while effectively releasing sweat generated during high-output cold weather sports. Ultra-fine 18.9-micron fibers and a flattering, high-waisted, and slim fit allowed our testing team to stay comfortable all day. And speaking of comfort, features like the gusseted crotch increase the range of motion, while the flatlock seams are thoughtfully placed to avoid distraction or discomfort from chafing.
Although we didn't encounter any durability issues during our testing period, we have tested several versions of these bottoms and know that the perforated ventilation panels can often be the first location where the fabric will fail. The perforated ventilation panels cover nearly half of these expensive bottoms, and we remain wary of their longevity. If long-term durability is a top concern, we suggest the similarly designed SmartWool Intraknit Thermal Merino Bottoms. That said, be prepared for a much more rigid and thicker construction that doesn't offer the same amount of comfort or freedom of movement. But for what it's worth, the latest update of the ZoneKnit gives us confidence that these bottoms are more durable than ever. If you're interested in a highly breathable design that enhances both the odor-resistance and wicking capabilities of 100% Merino wool, the 200 ZoneKnit offers high performance with a unique, modern, and stylish design that can't be beaten. Or, if you like the sound of the 200 ZoneKnit but are after a long underwear bottom made of thicker fabric, we've also tested the midweight version, the Icebreaker 260 ZoneKnit Merino Leggings. The 260 ZoneKnit is identical to the 200 ZoneKnit, with a little extra thickness in the upper thigh for additional warmth during the coldest months of the year. Ultimately, we selected the 200 ZoneKnit as our Merino wool favorite based on their lighter-weight fabric, which we believed offered a more versatile, year-round performance.
Weight: 4.90 oz | Material: 92% recycled polyester, 8% spandex
REASONS TO BUY
Supersoft Polartec fabric
Superior breathability
Exceptional warmth
Great fit enhances mobility
Recycled material
REASONS TO AVOID
Questionable durability
Fabric holds odor
Known for its amazing wicking power and breathability, the Patagonia Capilene Thermal Weight rises to the top for synthetic performance. Constructed of 92% recycled polyester and 8% spandex, this pant (though marketed as a thermal weight) has more of a midweight construction that provides optimal performance throughout the year. The see-through design allows air to penetrate the fabric, making the subsequent wicking power hard to beat. While synthetics aren't typically known for their next-to-skin comfort, we love how the Polartec power grid fleece feels against the skin and its stretchy fit that moves with our body.
Unfortunately, despite the HeiQ Fresh odor control treatment, these bottoms get smelly after only a few days of use, so we can't recommend them as our first choice for multi-day backcountry missions. The Capilene Thermal is admittedly a bit more niche — they aren't your “hang around at camp lounge pants.” However, they dry quickly, excelling at technical, high-output pursuits. If you seek a highly breathable synthetic pair of long underwear that doesn't skimp on comfort and fit, these will not disappoint. We also like Patagonia's Capilene Midweight Bottoms for a lighter weight, more affordable, and much more durable alternative, but we note they're not quite as warm, breathable, or quite as comfy as the Capilene Thermal Weight.
These bottoms (worn underneath our ski bibs) were the perfect layer for skiing Birch Mountain in the Eastern Sierra thanks to their added insulation on the summit and awesome breathability during the long climb.
Thicker bottom requires more room beneath your outer layers
If you've been wanting a Merino base layer but cringe at the average price tag, consider the competitively-priced Minus33 Franconia Midweight Wool Bottoms. These midweight leggings are constructed from 235 g/m² 100% Australian Merino Wool, providing super soft comfort next to your skin. Thanks to the tightly woven fabric, they are also in the running for some of the warmest bottoms we've ever tested. And while they do not feature fancy ventilation panels or perforated fabric like the Icebreaker 200 ZoneKnit Merino Leggings, the ultra-fine, 18.5-micron Merino wool naturally thermoregulates your body temperatures, and the looser fit allows more air to permeate the fabric and wick sweat away from the body.
Our testers felt the Franconia Midweight was true to size, but the fit is looser, so we recommend sizing down if you prefer a more athletic, slim-fitting bottom. Another fit you may prefer is that of the Baleaf Fleece Lined Thermal, which is more akin to yoga leggings than long underwear. You may also like the fitted REI Co-op Midweight Tights. Though we love the super soft Merino wool, we couldn't help but notice how easily the Franconia Midweight can stretch out and lose structure, loosening up with use. But don't worry; our tests showed you can restore their structure with one cycle in the washing machine. Even with all this stretching potential, the thin and low-profile elastic waistband effectively holds these bottoms in place, whether worn on their own or beneath ski bibs. All in all, we were impressed with the durability of these Merino wool bottoms and believe they offer a ton of value in exchange for a more modest price tag.
Though the Minus33 Franconia is an affordable option that features a 100% Merino wool design, the midweight fabric has less structure and requires a little more room to layer in your ski bibs.
Weight: 6.40 oz | Material: 92% polyester, 8% spandex
REASONS TO BUY
Affordable
Cute and fitted style
Easy to wear on their own
Smooth, silky, and stretchy fabric
REASONS TO AVOID
Fabric absorbs and holds moisture
Less comfortable compared to natural Merino fabrics
Polyester fabric retains odor immediately
The REI Co-op Midweight Tights offer great synthetic performance at an affordable price. The blended polyester and spandex fabric feels incredibly soft against the skin and features a four-way stretch, allowing a full range of motion. While more of a lightweight fabric, these tights offer ample warmth for the shoulder seasons. When paired with thicker insulating layers, they are also ideal for the colder months of the year. These tights are a great choice for numerous cold-weather activities, featuring a fit that's true to size and durable flatlock seams.
Unfortunately, we were not impressed by the garment's ability to release moisture from the fabric after some high-intensity activities. These tights did wick sweat away from our skin, but they pooled near the waistband and took longer to dry behind the knees. We also noticed that the fabric retained odor almost immediately after our testing began, and we couldn't find any mention of an odor control treatment like other top-performing synthetic bottoms. If odor control is an issue, check out the odor-free Ortovox 185 Rock'N'Wool Short Pants, which are great at wicking moisture. All gripes aside, these synthetic tights impressed our testers with a competitive performance and a favorable fit, especially given the modest price. We also tested REI's Lightweight version of this pant, which are even more affordable and dry quickly. Still, they're slightly less warm and lack the same durability as the thicker midweight design.
In order to measure the overall drying speed for the REI Midweight Tights, we dunked them into the Merced River before tossing them on a line to dry at our campsite while visiting Yosemite Valley.
Weight: 8.8 oz | Material: 87% Polyester, 13% spandex
REASONS TO BUY
Highly affordable
Comfortable and flattering high-waisted fit
Thigh and waistband pockets
Synthetic fabric breathes well and doesn't stink
REASONS TO AVOID
Fabric lacks warmth
Questionable durability
Not a traditional long underwear bottom
The Baleaf Fleece Lined Thermal is a highly affordable bottom that favors the design of a modern yoga or workout tight moreso than what you would typically expect from a traditional long underwear bottom. The synthetic polyester and spandex construction offers a fleece-lined interior for comfort next to your skin, and the thickness of a midweight construction supplies additional warmth. The spandex fabric allows the bottoms to offer a bit of stretch and a full range of motion, whether you're out for a trail run or holding your favorite yoga asana. The design also features three pockets, two of which run along the exterior of each thigh and are big enough for a smartphone or energy bar, and one more discreet pocket along the waistband big enough for a car key. The design is easy to layer thanks to a snug fit that is true to size and the high waistband, which allows other layers to fasten at your natural waistline. We love these tights for rock climbing as the harness easily layers below the thick, high waistband.
We really put these bottoms through the wringer during our spring testing period. We took them out for trail runs amongst the sharp and unforgiving plant life that lines the desert floor, wore them rock climbing in the very physical Indian Creek splitter cracks, and layered them below our ski bibs for spring backcountry tours in the High Sierra. After all that use and abuse, we noted some piling along the thick flatlock seams and one small hole (that didn't grow larger) on the exterior knee after snagging on a sharp sagebrush plant during one of our trail runs. Needless to say, our testing team was impressed with this highly affordable bottom that far exceeded its modest price. The comfortable, breathable modern design features a flattering yet functional fit that withstood all durability tests without retaining any odor in its synthetic fibers. That said, these bottoms are not traditional long underwear made for optimizing layered warmth in cold climates. If you need a warm pair with a more traditional build, consider the Icebreaker 260 ZoneKnit Merino Leggings. Nonetheless, the midnight Baleaf Fleece Lined Thermal offers a ton of versatility at a very affordable price.
The Baleaf Fleece Lined Thermal Pants offered enough durability to ascend the physical splitter cracks found in Indian Creek, Utah, while providing excellent comfort against the skin and a great fit that easily layered below our climbing harness.
Weight: 4.80 oz | Material: 84% polyester/16% elastane
REASONS TO BUY
Lightweight but amply warm
Versatile fit
Soft synthetic fabric
Bonus stash pocket on thigh
REASONS TO AVOID
Pricey
Merrow stitch seams accumulate fuzz from friction
The Arc'teryx Rho Bottom is super light, versatile, and high-performing. This long underwear bottom features some of the most comfortable, internally brushed synthetic fabric we experienced during testing, and it offers a great fit. We love the high-rise, thick waistband that is not only flattering but functional, in addition to the slim fit that aids in offloading moisture from the minimalist design. Like the Baleaf Fleece Lined Thermal, these were some of the only bottoms we tested that feature a stash pocket on the thigh, which is great for storing energy gels, a couple of keys, or a phone.
This versatile design provides enough warmth and modesty for trail runs in the spring and fall or when layered beneath your favorite ski bibs for added insulation throughout the winter. The Rho is a bit pricey compared to other lightweight synthetic options in this review and should be weighed against the REI Co-op Midweight Tights if you're shopping on a tighter budget. The merrow stitching on the Rho Bottoms — similar to a welded seam — gets fuzzy when encountering velcro or a lot of friction from additional layers. Still, the Rho is high-performing and highly versatile, the perfect layer for running, skiing, or yoga.
The Arc'teryx Rho Bottoms are a solid pair of leggings when worn on their own or layered below your ski bibs. They high-waisted fit is stretchy and comfortable, it also features a handy stash pockets for gels or bars.
The SmartWool Intraknit Thermal Merino Bottom quickly became our favorite pair of blended long underwear bottoms geared to optimize cold weather performance. The fabric blend takes advantage of Merino's odor-free benefits and the durability of polyester. But what sets these bottoms apart is their gender-specific pattern articulation and unique ventilation panels that increase breathability throughout the design while capturing warmth generated during activity.
The Intraknit's ability to keep us warm when moving in frigid temperatures during testing was truly impressive, but this design has some drawbacks. The overall thicker fabric increases bulk when layering while reducing drying speed at the same time. If you're looking for a wool pair to wear skiing that won't interfere with your ski boots, we recommend the Ortovox 185 Rock'N'Wool Short Pants, which stop mid calf. The Intraknit's 2" waistband hugs our curves nicely and keeps the pant securely in place, it was also typically the only portion of these bottoms that trapped moisture. Aside from these caveats, we recommend these bottoms to anyone searching for a pair with a more substantial and warmer weight that still performs well during high-output cold weather activities.
The SmartWool Intraknit Thermals feature a thicker fabric that adds some friction when combined with ski bibs, layers like rain and puffy pants are easier to layer due to a smoother interface between the fabrics.
Weight: 4.80 oz | Material: 100% Recycled polyester
REASONS TO BUY
Highly durable
Year-round warmth
Good thermoregulation
Slim-fitting, high-waisted design
Fast drying speed
REASONS TO AVOID
Not as comfortable as Merino wool
Retain body odor almost immediately
The Patagonia Capilene Midweight Bottoms is a consistent and reliable long underwear bottom, offering excellence in durability and overall workhorse performance season after season. Thanks to their 100% Recycled polyester construction that features flatlock seams and a gusseted crotch, these bottoms are built to go the distance. The hollow-core yarns and the diamond-grid patterning help these bottoms to thermoregulate effectively by trapping warm air, wicking sweat away from the skin, and releasing it through the fabric. They're essentially designed to keep you cool when it's hot and warm when it's cold. We love that they are solid enough to be worn as stand-alone leggings and thin enough to be layered below your ski bibs for additional warmth in the winter.
We're happy to report we have not encountered any durability issues with these bottoms, even after multiple years of testing. In fact, they've outlasted almost every other synthetic model that we have tested over the years. The flatlock seams and tightly woven diamond grid pattern synthetic fabric are still going strong, even though we've worn them rock climbing and trail running in the desert that surrounds the Eastern Sierras. The Patagonia Capilene Midweight Bottoms are an excellent choice for those wanting to maximize their investment for multiple years of use, and they come with a reasonable price tag. Another affordable option is the REI Midweight Tights — though they're nowhere near as durable.
The Midweight bottoms offer exceptional durability, whether worn on their own or within a layered system.
Credit: Trish Matheny
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The Ridge Inversion Leggings are the perfect affordable long johns for colder temperatures, whether traveling through the desert during the fall or earning your turns in the backcountry.
Credit: Lindsey Fell
How We Test Long Underwear for Women
When testing women's long underwear, we consider how each bottom can be useful. We take stock of what's on the market, selecting the highest-rated products with the best reputation. Then, we buy each layer at retail price and test them side-by-side for months at a time.
We've spent the last six years searching for the best pair of long underwear bottoms, which allowed us to record our experiences throughout all the possible cold weather conditions. We've taken each model on international trips and used each locally while climbing, biking, and exploring Colorado's San Juan Mountains and California's Sierras. After our field tests, we evaluate each product, score it, and share our findings and thoughts.
Our testing is divided across six key metrics:
Warmth (25% of overall score weighting)
Breathability (20% weighting)
Comfort and Fit (20% weighting)
Durability (15% weighting)
Drying Speed (10% weighting)
Layering Ability (10% weighting)
The Eastern Sierra is certainly a beautiful place for testing the drying speed of every pair of long underwear.
Credit: Trish Matheny
Why Trust GearLab
This review is spearheaded by Trish Matheny. After spending a very cold decade in the Tetons, she knows what she's looking for in long underwear performance. An avid rock climber, trail runner, and born-again splitboarder, Trish wears base layers almost daily when pursuing her passions amongst the elements in the Eastern Sierra. She hopes that by sharing her experiences, she can offer thoughtful recommendations to help you select the best layer for your backcountry adventures. Outdoor educator and avid adventurer Amber King laid the foundation of this review. She regularly opts for a pair of base layer bottoms when climbing, snowboarding, hiking, sailing, and trail running. As a result, she's stayed warm and comfortable in her travels, ranging from the Faroe Islands to the Cordillera Huayhuash of Peru.
The Icebreaker 260 Zone Legging is our all-time favorite long underwear bottom, from pancakes on rest days to alpine starts in the mountains.
The Smartwool Intraknit Thermal Merino Bottom features a thick and functional waistband measuring 2 inches.
Slow mornings in the desert just got better with the Kari Traa Rulle High Waist Pant.
Our testing team puts these layers to the test across all types of outdoor and everyday activities, assessing them for warmth, durability, and everything in between.
Analysis and Test Results
A solid long underwear bottom is a key part of any outdoor wardrobe. Designed to sit next to the skin, it should wick away moisture to keep your skin warm and dry. While each bottom could be used on its own in warm weather, a base layer is typically used as part of a layering system during the year's colder months. To find the best pair for different activities, we look at a range of base layer bottoms in various weights, from light to heavyweight.
What's the Best Value?
There are many great options out there that won't cost you an arm and a leg. When considering value, it's important to consider both performance and durability. The Ridge Merino Aspect is constructed from primarily Merino wool and boasts an affordable price tag relative to most competitors. Our testers were impressed by the flattering and functional fit, comfort next to the skin, and increased durability offered by the blended fabric of these affordable and stylish leggings. For just a few dollars more, the 100% Merino wool design of the Minus33 Franconia offers plush comfort and substantial warmth at a fraction of the cost of its popular wool competitors.
Though long underwear styles like the Thermajane are super affordable, they unfortunately often come up short when it comes to their overall performance.
Credit: Gus Landefeld
When it comes to value, the Patagonia Capilene Midweight Bottoms rise to the top of our list. They are followed closely by the impressive performance of the REI Co-op Midweight, which is especially notable considering it has one of the lowest price tags in this entire review. However, both are constructed from synthetic materials and are typically not as warm and cozy as Merino wool.
A great pair of bottoms layered with a roomy outer layer can make for a mighty comfortable combination when tackling late-season activities.
Credit: Gus Landefeld
Our testers love it when an inexpensive bottom outperforms its price tag, and this is precisely what happened with the Baleaf Fleece Lined Thermal bottom. This synthetic bottom favors the modern design of a yoga tight or workout bottom rather than a traditional pair of long underwear that prioritizes warmth. We were impressed with the high value offered in this versatile three-season bottom that supplies fleece-lined comfort and a great fit that offers easy layering and enough durability to wear as a stand-alone bottom.
The Baleaf Fleece Lined Thermal bottom outperforms its inexpensive price tag, offering a great fit along with versatile synthetic performance.
Credit: Gus Landefeld
Pro Savings Tip
Look for last year's colors on your favorite and more expensive long underwear bottoms. You can typically find them at a discount with the same great performance.
Warmth
The insulative warmth of a base layer bottom balances with breathability to provide great thermoregulation. When evaluating warmth, you should consider that most models are available in various weights. The higher the fabric weight, the warmer it is supposed to be. However, we've encountered plenty of layers that claim to be one weight and perform more like another. To help you navigate confusing marketing claims, we provide side-by-side comparisons and let you know our opinion regarding the effective fabric weight each pair of long underwear bottoms offers.
Thoughts Behind Thermoregulation
When it comes to warmth, there are two different schools of thought. The first is that a warmer base layer will lead to greater overall warmth. The second, a base layer bottom, should be as thin as possible and utilized just to wick away moisture, while a fleece or other layer will provide the additional warmth needed to withstand the elements. While neither is right or wrong, what you buy is based on your needs and preferences, so be sure to decide what is best for you before making your final decision.
During our testing period, we began by observing the fabrics and their construction, assessing the tightness and relative thickness of the weave. Then, we test warmth by playing and working in cold, inclement weather before sleeping in each pair under the stars on frosty nights. We carry our base layers on our adventures, cycling each pair in and out of use to see which offers the best insulation and warmth as a stand-alone piece or when worn underneath a pair of pants. We record our experiences, compare notes, and report back to you.
The Patagonia Capilene Thermal keeps us warm while we scream down these snowy hills in California.
Credit: Amber King
Through extensive testing, we learned that the natural organic fibers of Merino wool not only feel amazing against the skin but typically offer the best range of thermoregulation and warmth for the coldest days of the year. Merino wool base layer bottoms, like the Minus33 Franconia, the Ridge Merino Inversion, and the Meriwool Merino 250 Bottom offer the most warmth due to thicker fabrics that insulate very well on cold days.
The Minus33 Franconia offers a midweight 100% Merino wool design that features optimal warmth that's perfect foe everything from cold weather to performance to winter nights chilling by the fire.
Credit: Trish Matheny
If you dig the ventilation panels and optimized breathability, the Icebreaker 260 ZoneKnit and the Icebreaker 200 ZoneKnit are 100% Merino wool designs. In contrast, the SmartWool Intraknit Thermal Merino Bottom features a blend of Merino wool and polyester with enough structure to be worn independently. And while fully synthetic options aren't typically as warm as wool or wool blends, some contenders like the Patagonia Capilene Thermal Weight are closing that gap. Both of these bottoms offer a modern perspective on thermal insulation, increasing the overall warmth of the layer by increasing its ability to offload moisture. We recommend these performance bottoms for high output warmth during cold weather activity, but if you're looking for the warmest model for more sedentary activities or riding the chairlift, stick with the bottoms like the Ridge Merino Inversion and the Minus33 Franconia.
Cold weather performance just got better with the Smartwool Intraknit.
We were happy to have the Icebreaker 260 ZoneKnit bottoms layered below our jeans on this late season ascent of Lurking Fear on El Capitan.
Ventilation panels like the ones featured on the Smartwool Intraknit and the Icebreaker 200/260 ZoneKnit truly optimize breathability, whether worn on their own or layered below a pair of pants.
The Patagonia Capilene Midweight Bottoms feature a 100% recycled polyester construction that we consider a synthetic workhorse perfect for year-round use. The Capilene Midweight got the job done whether we needed additional insulation for sleeping out on cool summer nights, a stand-alone legging for spring and fall trail runs, or the perfect base layer for extra warmth during the coldest months of the year.
The Patagonia Capilene Midweight kept us warm while we kicked steps up McGee Mountain in the Eastern Sierra.
Credit: Steve Mace
Breathability
Breathability and wicking capabilities work together to ensure your skin stays dry, whether pushing the aerobic threshold or hanging out by the fire. To test breathability, we look at fabric thickness and type. We take each option out backcountry skiing, hiking, climbing, and running and test in warm and cold weather conditions. Finally, we evaluate the fabric to see if any moisture is retained within the fibers or if it stays dry as a bone.
Unsurprisingly, the most breathable long underwear bottoms are often the thinnest. Thinner, see-through materials allow air to pass through more readily, thus facilitating optimal evaporation. Some of the most breathable layers in this review are the Patagonia Capilene Thermal Weight. Since the Thermal Weight fabric is rather see-through, we don't recommend wearing them as stand-alone leggings. However, their lightweight design performs incredibly well in a layered system or with spandex bike shorts underneath.
The lofted grid pattern design aids the Patagonia Capilene Thermal Weight Bottoms in optimal breathability and wicking performance.
Credit: Trish Matheny
Bottoms like the Icebreaker 260 ZoneKnit, the Icebreaker 200 Zoneknit and the SmartWool Intraknit are perfect for backcountry or Nordic skiing when the temperature is decidedly cold (near to below freezing). And if you're curious, the primary difference between the Icebreaker Zoneknit bottoms and the SmartWool Intraknit is mainly that the ZoneKnit bottoms are constructed from 100% Merino wool while the Intraknit come in a Merino wool blend that feels more rigid. This difference in fabric affects warmth, breathability, comfort, and durability. As a result, we also recommend layering the 200 Zoneknit rather than wearing them as a stand-alone pair of leggings.
Ventilation panels on the Smartwool Intraknit work to shed excess sweat and heat that builds up after pushing the pace during cold weather training.
Credit: Trish Matheny
The Patagonia Thermal Weight, Icebreaker Zoneknit, and SmartWool Intraknit bottoms receive higher scores because they have special ventilation zones that target specific areas of the lower body that are prone to absorbing body heat and sweat. These body-mapped ventilation panels promote airflow in these areas, offloading moisture while maintaining body heat.
The 100% Merino Wool design of the Icebreaker 200 ZoneKnit features body-mapping technology and specific ventilation panels that feature perforated material to shed moisture and trap body heat.
Credit: Trish Matheny
Synthetic fabrics are often known for their rigid structure. An exception to this rule is the Arc'teryx Rho. This layer quickly became a go-to for spring training runs and backcountry skiing due to the ability of the soft, brushed Torrent fabric to wick and shed moisture. Another design that offers less rigidity is the REI Co-op Midweight, but it, unfortunately, didn't breathe as well as its ventilated competitors, often retaining sweat in the waistband and requiring more time to dry fully. While synthetic fabrics are typically more porous than wool, the Midweight features a tightly woven, slim-fitting polyester fabric. On the trail, we prefer synthetics such as the Rho, which features a lighter-weight construction.
Moisture wicking capabilities made the Rho one of our go-to's for shoulder season training and this stash pocket really came in handy for energy gels, bars, or a smartphone.
Credit: Trish Matheny
Long underwear bottoms like the Minus33 Franconia, the Ridge Merino Inversion, the SmartWool Classic Thermal, and the Meriwool Merino 250 are simply much thicker in construction and not exactly known for their breathability. When we layered these bottoms underneath another pair of pants, we noticed they could not wick moisture away from the body, often accumulating sweat in the fabric, which can get cold quickly. Throughout testing, we observed that the wool contenders typically perform best when sweaty because wool can retain heat, even when wet, much better than thicker synthetic fabrics. Consider these thicker weights for activities such as nightly winter dog walks, hanging out in the yurt next to the fire after a day of backcountry skiing, or keeping you warm on the chairlift on the coldest winter days.
Thick midweight options, like the Meriwool Merino 250 Bottom, provide ton of warmth for the coldest months of the year, however, they can often leave more to be desired in terms of breathability.
Credit: Trish Matheny
Comfort and Fit
The best you can hope for is a long underwear bottom that'll feel cozy from the ski hill to your bed. Bottoms that fit correctly should also offer the highest level of comfort throughout an entire day of adventures. We put each bottom on to test this metric, wearing them all day and recording our experiences.
Of all the 100% Merino wool options we tested, the Icebreaker 200 ZoneKnit was our clear favorite and quickly became our go-to thanks to the versatility of these bottoms. The high-waisted fit, along with the body mapping technology, helps these tights to fit like a glove. The Merino wool is soft next to your skin, and the fit is modern and flattering. Not far behind was the Icebreaker 260 ZoneKnit, which features the same high-waisted design as the 200 ZoneKnit. The only difference is the thickness of the material, which feels just as soft next to your skin. And though the Minus33 Franconia doesn't have anything near the bells and whistles of the 200 ZoneKnit, they offer a soft and cozy 100% Merino wool design with a thin, elastic waistband that tops our list for all-day comfort.
The flattering high-waisted design features a low profile brushed elastic waistband that effectively holds these leggings in place during active mountain pursuits.
A flattering high-waisted design, flatlock seams, and 100% Merino wool make the Icebreaker 260 ZoneKnit leggings some of the most comfortable that we tested.
Though not as high tech as other waistbands featured in this review, the simple design of the Minus33 Franconia holds the layer in place, even when the Merino wool stretches out during use.
Our testers love the flattering high-waisted designs of the Icebreaker 200 ZoneKnit, the Icebreaker 260 ZoneKnit, and the Minus33 Franconia which truly stood apart from the competition with their noticeably softer Merino wool constructions.
The SmartWool Classic Thermal are quite comfortable. These bottoms are thick enough to keep you warm and provide enough coverage to be worn independently; however, the fabric eventually sags throughout the day and doesn't have enough shape to hug our curves. Like many other Merino wool contenders, these are best worn underneath another layer or as loungewear around the house. Our testers love the Ridge Merino Inversion, a high-waisted design for added coverage and a functional (yet comfortable) thick elastic waistband. Other lighter Merino wool bottoms like the Icebreaker 200 Oasis and the Ortovox 185 Rock'N'Wool Short Pants are also super comfortable and have a softer feel next to the skin, thanks to their 100% Merino wool fabric.
The ultra fine Merino wool construction of the Ortovox 185 Short Pants feels cozy next to our skin and we love the brushed elastic waistband.
Credit: Claire Maurey
Synthetic bottoms often feature hollow fibers, resulting in a less comfortable feeling next to the skin. Still, we noticed a couple of options that prove this theory obsolete. The Arc'teryx Rho and the Patagonia Thermal Weight feature a brushed interior or Polartec fleece that's highly comfortable in addition to their superior, high-waisted fits.
We love the stretchy fit of the Patagonia Capilene Thermal Weight and the Polartec fleece interior feels amazing next to our skin.
Credit: Trish Matheny
Another synthetic option that stands out is the Baleaf Fleece Lined Thermal bottom that offers a fit similar to a modern yoga tight as well as next-to-skin comfort thanks to the fleece-lined interior. The thick, high waistband supplies a flattering fit for a variety of body shapes and sizes, and the spandex in the design allows for enough stretch to support freedom of movement.
The Baleaf Fleece Lined Thermal bottom is one of the least expensive bottoms that we tested, offering a comfortable fleece-lined interior in addition to a great fit that is similar to that of a modern yoga pant or synthetic workout tight.
Credit: Gus Landefeld
One of our favorite blended options is the Ridge Merino Aspect. These bottoms are constructed from 80% Merino wool, 14% nylon, and 6% spandex and feature a thick, high-rise waistband. This stylish waistband highlights the flattering fit of these bottoms, makes them more comfortable next to the skin, and helps keep them in place whether you're out for a training session or doing physical therapy exercises.
The Ridge Merino Aspects features a stylish and flatting high waist that holds these bottoms in place during activities.
Credit: Trish Matheny
Durability
We understand that durability is key when purchasing a layer essential for your winter kit. You don't want to invest in bottoms only to find out that they fray, rip, and wear out after only a few uses. To measure overall durability, we observe the wear and tear throughout our testing period until a new product iteration is developed and included in the lineup. We ski, climb, and trail run in each pair of long underwear and record our experiences while layered underneath thicker fabrics or simply worn on their own. We evaluate the quality and craftsmanship of every product by looking at its seams and stitching. After walking through brambles, sliding through canyons, and skinning uphill underneath snow pants, we get a good idea of the durability each layer has to offer. We continue to update this section throughout the year as we gather more information.
If the most durable bottom out there is what you prefer, look for thick fabrics made from synthetic materials. These strong fibers are often stiffer and more rigid, thereby providing better resistance to abrasion and stretch when compared to their Merino wool competitors. The most durable layer we've tested so far is the Patagonia Capilene Midweight. We've tested these bottoms for years and are happy to report they still look great after hundreds of miles and intense use on the trails. The Midweight and Patagonia Capilene Thermal Weight offer a durable elastic waistband and flatlock seams, which inspire confidence in their construction. We only wish the odor treatment was as effective because these layers often smell after minimal use.
The Capilene Midweight features durable and high quality flatlock seams that are built to last multiple seasons of extensive use.
Credit: Trish Matheny
Perhaps we were the most curious about how the Patagonia Thermal Weight would hold up during intense activity due to their see-through, ultra-thin design. We are pleased to report that we have experienced no durability issues thus far, though the fabric is some of the thinnest we've tested. We can't imagine it will last as long as a thicker, tightly-woven, and more rigid synthetic design.
The Patagonia Capilene Thermal Weight is a super breathable design that features flatlock seams in high traffic areas for added comfort and overall structure, however, it is not as durable as other synthetics due to the see-through lofted material.
Credit: Trish Matheny
Another impressive bottom is the Arc'teryx Rho Bottom, which features a high-quality merrow stitch similar to a welded seam. The only issue we noticed with these bottoms was the tendency for the seams to get a little fuzzy if there was friction between the bottom and our ski bibs; otherwise, they were with us for many training miles without issue. Similar to the Rho Bottom is the Baleaf Fleece Lined Thermal base legging, which we noted also pilled along the thick flatlock seams in high-traffic areas like the inner thigh. We also snagged this bottom on a sagebrush plant during one of our trail runs and ripped a tiny hole in the bottom, though we were pleased when the hole remained small and didn't grow in size even after continued use.
The Rho Bottoms feature strategically placed and durable seams that still going strong.
Credit: Trish Matheny
A thicker construction is seemingly more durable than a thin one. However, thicker contenders can snag more easily and pill faster than thinner options. Of the 100% Merino wool bottoms, the Icebreaker 200 Oasis is notable here. The material is tightly knit and seems super burly, even for its thinner construction. The Minus33 Franconia and the Meriwool 250 are a couple of other impressive 100% Merino wool designs to consider if you don't mind a midweight thickness. We were especially impressed by the Minus33 Franconia because the fabric never snagged or pilled after tons of use.
The Minus33 Franconia features flatlock seams that give the bottoms structure, however, the ultrafine and super soft 100% Merino wool design may not offer the same durability as its synthetic competitors. ough the design is very simple, the flatlock seams and thick construction give our testing team confidence when it comes to overall durability.
Credit: Trish Matheny
The Kari Traa Rose High Waist features a durable, thick, and well-made 100% Merino wool design reinforced with flatlock seams. Another impressive midweight wool design is the Ridge Merino Inversion, which has held up to rigorous use after multiple seasons of heavy use. Bottoms that integrate Merino wool and synthetic fibers into their construction, such as the SmartWool Intraknit and Ridge Merino Aspect, also tend to wear and tear much better than their 100% Merino wool competitors.
We experienced no durability issues with the Kari Traa Rose High Waist Pant, which features a high quality construction.
The Smartwool Intraknit features a thickly-constructed Merino wool blend that is still going strong.
The 240 g/m² Merino wool blended fabric of the Ridge Aspect also features flatlock seams for added durability and structure.
Pictured above, the Kari Traa Rose, the Smartwool Intraknit, and the Ridge Merino Aspect all offered thick, midweight designs and gave our testers confidence in overall durability despite their Merino wool construction.
Drying Speed
Measuring the overall drying speed for each layer was an important undertaking for us. For each pair of long underwear, we simulated what it would be like to soak and dry each layer for an extended period in the backcountry.
Our results revealed that synthetic fabrics with lightweight construction typically offer the fastest drying speeds. At the same time, Merino wool layers typically require much longer to dry completely.
We soaked, wrung out, and hung each and every long underwear bottom on our climbing rope to objectively evaluate the drying speed side by side.
Credit: Trish Matheny
As always, we love it when a long underwear bottom outperforms our expectations, so we're happy to report that the Patagonia Capilene Midweight Bottom, though considered a midweight fabric, offered the fastest drying speed by a long shot, drying in only 32 minutes.
If you're after the fastest drying speed, look no further than Patagonia's Capilene Midweight bottoms.
Credit: Trish Matheny
Other synthetic options that offer fast drying speeds include the Patagonia Thermal Weight and the Arc'teryx Rho, both drying in less than 45 minutes. While 100% Merino wool designs often require longer drying, the 100% Merino wool construction of the Icebreaker 200 ZoneKnit dried almost as fast as its synthetic competition. Completely dry in only 51 minutes, we hypothesize the 200 ZoneKnit increased its drying speed due to the perforated fabric and ventilation panels covering most of these bottoms.
The lightweight 200 g/m² 100% Merino wool design features perforated fabric along with thoughtful ventilation panels for an increased drying speed on the line and on the body post workout.
Credit: Trish Matheny
Though most midweight Merino wool bottoms took longer to dry due to a thicker construction devoid of their synthetic competition's porous structure, a few stood apart from the rest. The Minus 33 Franconia and the SmartWool Classic All-Season Merino Bottom are notable here, as are the Icebreaker 200 Oasis Leggings. Of the thickest Merino wool bottoms, we suspect the polyester blend aids in the faster drying speed for the SmartWool Classic All-Season and SmartWool Intraknit.
Though the Minus33 Franconia is a midweight 100% Merino wool design, it offers a competitive drying speed, especially for a thicker long underwear bottom.
Credit: Trish Matheny
Layering Ability
There is a lot to consider when evaluating the layering ability of each base layer. We tried to assemble various cold weather kits to determine which long underwear bottom performed best within a layered system. Whether layering underneath the grippy inner fabric of our favorite ski bibs or below the smooth interface of our puffy and rain pants, we gave the highest scores to the layers that required the least amount of adjustment, had the smoothest fabric, and promoted mobility rather than limiting our range of motion.
The Merino wool bottoms at the top of our list include the Icebreaker 200 ZoneKnit and the Icebreaker 200 Oasis. We love the ZoneKnit and the Oasis for their smooth wool fabric interface and low-profile elastic waistband, though we noticed some piling on the Oasis from some friction after skinning uphill. The ZoneKnit layered perfectly beneath our climbing pants on a winter mission to climb multi-pitch in Index, Washington.
When we set off for a multi-pitch rock climb, racing the setting sun during our winter testing period, the 200 ZoneKnit layered easily below our climbing pants, providing excellent thermoregulation.
Credit: Mik Metzler
Other top wool performers include the Ridge Merino Aspect and the 3/4 length design of the Ortovox 185 Rock'N'Wool Short Pants. The five-inch thick waistband on the Aspect bottoms allowed for easy layering, especially if the pants you pull over top fasten at the natural waistline. The Rock'N'Wool Short Pants offer the least bulk in any layered system we assembled due to their 3/4 length, which rests just below the knee, leaving just enough extra room for tucking beneath the very top of our ski socks. We appreciated the Short Pant design when the temperatures heated up during our spring skiing season, leaving more room in our ski boots and less material to absorb moisture when moving quickly uphill.
The ease of layering the Ortovox Short Pants isn't limited to the 3/4 length, the lightweight Merino wool also easily zips into our ski bibs.
The Ridge Merino Aspect bottoms feature a smooth interface that layered well below our jeans and offered plenty of mobility to climb in.
Bottoms like the Ortovox 185 make layering easy due to their compatibility with ski boots, while the thick five-inch waistband of the Ridge Merino Aspect allows layers over the top to more easily fasten at the natural waistline.
Our high-performing synthetic options include the REI Lightweight Base Layer Tights and the Patagonia Capilene Midweight. The REI Lightweight features a super low profile and ultralight fabric, which took up the least space in our ski bibs, and a smooth interface between our puffy and rain pants. We love these bottoms for spring skiing and appreciate the extra room for increased airflow and range of motion when pursuing backcountry ski objectives. The higher waist and smooth 100% polyester fabric increase the glide between additional layers over the top, and we love that the waistband, though double-banded, sits above our natural waistline and reduces bulk, allowing other layers to lay flat against the skin.
The Patagonia Capilene Midweight features a very smooth synthetic fabric and high-waist, making them easy to layer under ski bibs or puffy pants.
Credit: Trish Matheny
Another notable option is the SmartWool Classic All-Season Merino Bottom, which didn't impress us with durability. Still, the superlight fabric almost feels like you have nothing on beneath your ski bibs. The Merino wool design also has a touch of nylon, which we suspect allows for a better interface with additional layers. A bit of a surprise in this category was the Ridge Merino Inversion, which features a stripped-down classic design and a higher waist that may take up a little more room than a lightweight option. However, it never reduced our mobility, especially considering it is the only heavyweight option in this review.
Although midweight and heavyweight fabrics often require more space in your layered system, we found the Ridge Inversion's Merino wool fabric to offer a smooth interface and a high-waisted fit for additional coverage and ease of layering.
Credit: Trish Matheny
Conclusion
We've come a long way since long underwear was made from super thick, itchy wool or a cotton-dimpled suit. With so many long underwear options on the market, it's necessary to take the time to select the pieces that will not only offer a high level of comfort but also meet your performance needs. We hope our in-depth research has assisted you in your quest for the perfect base layer bottoms and that you stay warm and dry throughout the cold months of the year.
The Patagonia Capilene Thermal Weight is the perfect layer for big spring objectives when you need the added warmth on the summit in addition to exceptional breathability during the climb.
