Reviews You Can Rely On

The 7 Best Long Underwear for Women of 2024

We put women's long underwear to the test, evaluating top models from Icebreaker, Patagonia, Smartwool, Arc'teryx, Ridge Merino, REI, and more to find the very best
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Best Long Underwear for Women of 2024
After 4 years of testing and multiple updates, we've selected the top performers for Women's Long Underwear.
Credit: Steve Mace
Friday December 8, 2023

Our team has tested close to 50 pairs of the best long underwear for women over the last 8 years, including the top 18 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.

If you're looking for more lower-body layering options, we've also tested the best women's travel underwear and the most popular hiking pants. For your upper body, we've reviewed the best women's base layer tops and best fleece jackets for women.

Editor's Note: We updated this review on December 8, 2023, to include new products from Icebreaker, Ridge Merino, Black Diamond, and Patagonia, with adjustments to our award-winning lineup.

Related: Best Long Underwear for Men

Top 18 Product Ratings

Displaying 1 - 5 of 18
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Awards   Top Pick Award Best Buy Award Editors' Choice Award 
Price $79.00 at REI
Compare at 2 sellers
$44.98 at Backcountry$81.32 at Amazon
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$55 List
$54.95 at REI
$165 List
$140.00 at Amazon
Overall Score
73
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82
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Pros Comfortable on the skin, breathable, good fit, ample warmth, cute colors and designs, recycled materials100% Merino wool construction, naturally odor-free, durable flatlock seamsAwesome breathability and thermoregulation, highly functional waistband, great mid rise fit, articulated design increases mobilitySmooth and silky fabric, easy to wear alone or when layered, cute and fitted style, affordableWarm and cozy, body-mapped technology improves breathability, gusseted crotch for increased range of motion, feminine fit that's true to size, odor resistant
Cons Less durable than previous versions, holds smell almost immediatelyThicker fabric doesn't breathe well, waistband holds moisture, distracting seams, expensiveExpensive, longer drying speed, thicker waistband creates bulk when layered, performance fabric lacks comfortAbsorbs and holds moisture, fabric retains odor immediatelyExpensive, perforated fabric subject to durability issues
Bottom Line A synthetic long underwear bottom with an all around impressive performance at a fair priceTrue to size with a thick waistband that layers well, sadly these bottoms are itchy, the design details aren't well executed, and breathability is poorThese high performing midweight bottoms maximize warmth through strategic ventilation for optimal moisture management during cold weather conditionsThis synthetic base layer option features a soft and stretchy polyester fabric that offers moderate levels of warmth and breathability for an affordable priceDesigned 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
Rating Categories Patagonia Capilene... Kari Traa Rose High... Smartwool Intraknit... REI Co-op Midweight... Icebreaker 260 Zone...
Warmth (25%)
7.0
7.0
8.5
7.0
9.0
Breathability (20%)
6.0
5.0
8.0
6.0
9.0
Comfort and Fit (20%)
7.0
6.0
7.0
8.0
8.5
Durability (15%) Sort Icon
9.0
8.0
8.0
7.0
7.0
Drying Speed (10%)
9.0
6.0
6.0
8.0
6.0
Layering Ability (10%)
7.0
5.0
6.0
7.0
8.0
Specs Patagonia Capilene... Kari Traa Rose High... Smartwool Intraknit... REI Co-op Midweight... Icebreaker 260 Zone...
Material 100% Recycled polyester 100% Merino wool 52% Merino Wool, 45% polyester, 2% elastane, 1% polyamide 92% Polyester, 8% spandex 100% Merino wool
Listed Fabric Weight (g/m²) 147 g/m² 240 g/m² Not disclosed Not disclosed 260 g/m²
Weight Class Midweight Midweight Midweight Midweight Midweight
Measured Weight (size Small) 4.80 oz 7.04 oz 8.32 oz 6.40 oz 6.69 oz
Cuts Avaliable Full length Full length Full length Full length Full length
Smelly Over Time? Yes No No Yes No
Odor Control Fabric HeiQ Fresh Naturally odor resistant Merino yes, polyester no N/A Naturally odor resistant


Best Merino Women's Long Underwear


Icebreaker 260 ZoneKnit Merino Leggings - Women's


82
OVERALL
SCORE
  • Warmth 9.0
  • Breathability 9.0
  • Comfort and Fit 8.5
  • Durability 7.0
  • Drying Speed 6.0
  • Layering Ability 8.0
Weight: 6.69 oz | Material: 100% Merino wool
REASONS TO BUY
Very warm
Body-mapping technology upgrades breathability
Feminine fit that's true to size without rigidity
Odor-free
REASONS TO AVOID
Expensive
Too warm for year-round use

The Icebreaker 260 ZoneKnit Merino Leggings offer exceptional performance within a 100% Merino wool design. A tightly woven, 260 g/m² fabric, along with body-mapped ventilation panels in specific locations, helps these bottoms insulate while effectively releasing sweat. Ultra-fine 18.9-micron fibers and a flattering, slim fit allowed our testing team to stay comfortable all day long. 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.

It is worth mentioning that the thicker fabric weight of the 260 ZoneKnit bottoms requires a longer drying time, even with all of the additional ventilation. The perforated ventilation panels cover nearly half of these bottoms, and we remain weary of the longevity of these expensive bottoms. If long-term durability is a top concern, we suggest the similarly designed SmartWool Intraknit Thermal Merino Bottoms. But for what it's worth, we've tested multiple generations of the 260 ZoneKnit, and the latest update gives us confidence that these bottoms are more durable than ever before. If you're interested in a warm, highly breathable design that enhances both the odor-resistance and wicking capabilities of 100% Merino wool, the 260 ZoneKnit offers performance with a modern, stylish design that can't be beat.

Read more: Icebreaker 260 ZoneKnit Merino Leggings review

Our testing team wears each long underwear bottom on their own as well as within a layered kit to assess overall warmth and thermoregulation during a variety of activities.
Credit: Trish Matheny

Best Synthetic Women's Long Underwear


Patagonia Capilene Thermal Weight Bottoms - Women's


81
OVERALL
SCORE
  • Warmth 8.5
  • Breathability 9.0
  • Comfort and Fit 8.0
  • Durability 6.5
  • Drying Speed 8.5
  • Layering Ability 7.0
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 most of the year. The see-through design allows air to penetrate the fabric, and the subsequent wicking power is 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, in addition to the stretchy fit that moves with our body.

Unfortunately, despite the odor control treatment, these bottoms get smelly after only a few days of use, so they aren't 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 are seeking 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 and more affordable alternative, although they're not quite as warm, breathable, or quite as comfy as the Capilene Thermal Weight.

Read more: Patagonia Capilene Thermal Weight review

When skiing from the sage to summit as they say, we were happy we selected these bottoms (worn beneath our bibs) for their added insulation on the summit and incredible breathability on the effortful climb.
Credit: Lisa Coleman

Best Value for Merino Bottoms


Ridge Merino Aspect High Rise Bottoms


80
OVERALL
SCORE
  • Warmth 7.0
  • Breathability 8.0
  • Comfort and Fit 9.5
  • Durability 7.0
  • Drying Speed 8.0
  • Layering Ability 8.5
Weight: 6.74 oz | Material: 80% Merino wool, 14% Nylon, 6% Spandex
REASONS TO BUY
Affordable
Thick waistband adds style and warmth
Flattering fit is easy to layer
Odor-free
REASONS TO AVOID
Not as comfortable as 100% Merino wool
Lighter-colored fabrics show sweat and moisture

If you've been wanting a Merino base layer but cringe at the average price tag, consider the competitively-priced Ridge Merino Aspect High Rise Bottoms. These midweight bottoms feature a sleek, 5-inch waistband that adds warmth to the core as well as style and function. The fabric is constructed from 240 g/m² Merino wool, 14% nylon, and 6% spandex, reinforced by Ridge Merino's (m)Force Technology. This unique blend gives these bottoms the structure of leggings and the softness of a Merino wool long underwear bottom. Even though they do not feature fancy ventilation panels or perforated fabric, the ultra-fine, 18.5-micron Merino wool naturally thermoregulates your body temperatures, making these bottoms a versatile option for cross-training and backcountry skiing.

The Aspect High Rise is true to size and features a slim fit that is easy to layer. The thick waistband locks the bottoms into place, often requiring little adjustment, even when striking your favorite yoga pose. Though their fabric weight would suggest a midweight design, they have the look and feel of a lighter-weight pair of bottoms. They are warm enough to be worn on their own in temperatures down to the 40 °Fs, however, anything colder and we suggest you layer up. Ridge Merino also offers the Inversion Heavyweight Merino Leggings, if you're seeking ultimate warmth. While we didn't experience any durability issues with the Aspect bottoms during testing, we can't imagine the primarily Merino wool construction will hold up as long as its synthetic counterparts. But we still believe these affordable bottoms are well worth the hype, providing enough warmth, breathability, and performance so you can stay focused on your training goals both on and off the slopes.

Read more: Ridge Aspect Merino High Rise review

We were happy to have the Ridge Merino Aspect leggings layered below our jeans during a late season ascent of a multi-pitch rock climb in the Wheeler Crest.
Credit: Trish Matheny

Best Value for Synthetic Bottoms


REI Co-op Midweight Tights - Women's


71
OVERALL
SCORE
  • Warmth 7.0
  • Breathability 6.0
  • Comfort and Fit 8.0
  • Durability 7.0
  • Drying Speed 8.0
  • Layering Ability 7.0
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 that allows for 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. Featuring a fit that's true to size as well as durable flatlock seams, these tights are a great choice for a variety of cold-weather activities.

Unfortunately, we were not impressed by the garment's ability to release moisture from the fabric after some high-intensity activities. While these tights wicked sweat away from our skin, it pooled near the waistband and took longer to dry. We also noticed that the fabric retained odor almost immediately after our testing period began. All complaints aside, these synthetic tights impressed our testers with a competitive performance, especially considering the modest price tag. We also tested REI's Lightweight version of this pant, which are even more affordable and dry quicker, but they're slightly less warm and durable.

Read more: REI Co-op Midweight Tights review

While visiting Yosemite NP, we dunked the REI Midweight Tights in the Merced in order to freshen up and measure their drying speed.
Credit: Trish Matheny

Best Multi-Sport Performance


Arc'teryx Rho Bottom - Women's


78
OVERALL
SCORE
  • Warmth 7.5
  • Breathability 8.0
  • Comfort and Fit 9.0
  • Durability 6.5
  • Drying Speed 8.0
  • Layering Ability 7.5
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 a super light, versatile, and high-performing long underwear bottom that features some of the most comfortable, internally brushed synthetic fabric along with 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. These were some of the only bottoms that 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 to be worn on its own 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 considered 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.

Read more: Arc'teryx Rho Bottom

Our favorite pair of long underwear for multi-sport performance are the Rho Bottoms, thanks to a stretchy and comfortable design that features a handy stash pocket and can be worn on its own or within a cold weather layered system.
Credit: Trish Matheny

Best Cold Weather Performance


Smartwool Intraknit Thermal Merino Bottom - Women's


75
OVERALL
SCORE
  • Warmth 8.5
  • Breathability 8.0
  • Comfort and Fit 7.0
  • Durability 8.0
  • Drying Speed 6.0
  • Layering Ability 6.0
Weight: 8.32 oz | Material: 52% Merino wool, 45% polyester, 2% elastane, 1% polyamide
REASONS TO BUY
Awesome breathability
Optimal thermoregulation
Highly functional waistband
Articulated design increases mobility
REASONS TO AVOID
Expensive
Longer drying time
Performance fabric lacks comfort
Thicker waistband creates bulk when layered

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 utilizes the odor-free benefits of Merino along with the durability of polyester. But what really sets these bottoms apart from the rest is their gender-specific pattern articulation and unique ventilation panels that increase breathability throughout the design while capturing warmth generated during activity.

While we are truly impressed by the ability of the Intraknit to keep us warm when moving in frigid temperatures, this design is not without some caveats. The overall thicker fabric not only increases bulk when layering but also reduces the drying speed. And while we love the 2" waistband for the way it hugs our curves and keeps these bottoms in place, the waistband was typically the only portion of these bottoms that would trap moisture. Those things aside, if you're looking for long underwear bottoms with a more substantial and warmer weight but that still perform well during high-output cold weather activities, this is the layer for you. If you're seeking a wool pair to wear skiing that won't interfere with your ski boots, we recommend the Ortovox 185 Rock'N'Wool Short Pants.

Read more: SmartWool Intraknit Thermal Merino Bottom

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.
Credit: Trish Matheny

Best Lightweight Performance


Odlo Performance Light Bottoms - Women's


70
OVERALL
SCORE
  • Warmth 4.0
  • Breathability 9.0
  • Comfort and Fit 8.5
  • Durability 5.0
  • Drying Speed 8.5
  • Layering Ability 9.0
Weight: 3.84 oz | Material: 69% polyester, 27% polyamide, 4% elastane
REASONS TO BUY
Very breathable with excellent wicking power
Good thermoregulation
Snug, active fit
Super light, quick-drying material
REASONS TO AVOID
Not as comfortable as Merino wool
Lightweight material can tear if you're not careful

The Odlo Performance Light Bottoms are the lightest pair of long underwear bottoms that we tested. This pant is built for picking up the pace in cool weather, featuring synthetic materials with ventilation panels throughout the length of the legging to offer superior wicking ability and thermoregulation. Because the material is ultralight, we recommend this layer to provide extra warmth during trail runs at the change of season or layered below pants for Nordic skis during the winter months.

We're proud to report that even after two years of testing, we've experienced no durability issues with these bottoms. However, the material is so lightweight that we can imagine they could snag if not properly cared for. We also do not recommend sizing up, as the snug fit is meant to hug your curves, aid in moisture management, and allow for easy layering. The Performance Light Bottoms are a solid option for the athlete looking to maximize performance year-round, and they are available at a reasonable price, too. The REI Midweight Tights are another affordable option worth considering — they're warmer than the Odlo, but less breathable.

Read more: Odlo Performance Light Bottoms review

The minimalist Odlo Performance Light Bottoms were one of the fastest to dry on the line during our spring testing period.
Credit: Trish Matheny

Compare Products

select up to 5 products to compare
Score Product Price
82
Icebreaker 260 ZoneKnit Merino Leggings - Women's
Best Merino Women's Long Underwear
$165
Editors' Choice Award
81
Patagonia Capilene Thermal Weight Bottoms - Women's
Best Synthetic Women's Long Underwear
$99
Editors' Choice Award
80
Ridge Merino Aspect High Rise Bottoms
Best Value for Merino Bottoms
$75
Best Buy Award
78
Arc'teryx Rho Bottom - Women's
Best Multi-Sport Performance
$100
Top Pick Award
76
Ridge Merino Inversion Heavyweight Merino Leggings - Women's
$80
75
Smartwool Intraknit Thermal Merino Bottom - Women's
Best Cold Weather Performance
$130
Top Pick Award
74
Icebreaker 200 Oasis Leggings - Women's
$105
74
Patagonia Capilene Air Bottoms - Women's
$139
73
Patagonia Capilene Midweight Bottoms - Women's
$79
72
Ortovox 185 Rock'N'Wool Short Pants - Women's
$100
71
REI Co-op Midweight Tights - Women's
Best Value for Synthetic Bottoms
$55
Best Buy Award
70
Odlo Performance Light Bottoms - Women's
Best Lightweight Performance
$65
Top Pick Award
70
REI Co-op Lightweight Base Layer Tights - Women's
$40
69
Smartwool Classic Thermal Merino Bottoms - Women's
$115
68
Black Diamond Solution 150 Merino Full Length Bottom - Women's
$110
66
Meriwool Merino 250 Bottom - Women's
$60
65
Smartwool Classic All-Season Merino Bottom - Women's
$90
63
Kari Traa Rose High Waist Pant
$110

long underwear womens - the ridge inversion leggings are the perfect affordable long johns...
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

Why You Should Trust Us


When testing women's long underwear, we consider the different ways 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 four 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)

long underwear womens - the eastern sierra is certainly a beautiful place for testing the...
The Eastern Sierra is certainly a beautiful place for testing the drying speed of every pair of long underwear.
Credit: Trish Matheny

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. When climbing, snowboarding, hiking, sailing, and trail running, she regularly opts for a pair of base layer bottoms. 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...
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...
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...
Slow mornings in the desert just got better with the Kari Traa Rulle High Waist Pant.

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 can be used on its own in warm weather, it is typically used in a layered system during the colder months of the year. To find the best pair for different activities, we look at a range of base layer bottoms in a variety of weights, from light to heavyweight.


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-skin, and increased durability offered by the blended fabric of these affordable and stylish leggings.

We refer to the Patagonia Capilene Midweight as our synthetic workhorse, followed closely by the Odlo Performance Light Bottoms — and both come in at a reasonable price. We were impressed by the performance of the REI Co-op Midweight, especially considering it has one of the lowest price tags in this entire review. However, all three are constructed out of synthetic materials, which are typically not as warm and cozy as Merino wool.

long underwear womens - featuring super stretchy and durable synthetic fabric, the rei...
Featuring super stretchy and durable synthetic fabric, the REI Midweight are available at a price that won't break the bank.
Credit: Lindsey Fell

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 first consider that most models are available in a variety of different weights. The higher the fabric weight, the warmer it is supposed to be. However, we've come across 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 offered by each pair of long underwear bottoms.


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 warmth overall. The second is that a base layer bottom should be as thin as possible, 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 personal needs and preferences, so be sure to decide what is best for you prior to 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 with us, cycling them out to see which offers the best insulation and warmth as a stand-alone piece or underneath a pair of pants. We record our experiences, compare notes, and report back to you.

long underwear womens - the patagonia capilene thermal keeps us warm while we scream down...
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 Ridge Merino Inversion and the Meriwool Merino 250 Bottom offer the most warmth due to thicker fabrics that insulate very well on cold days.

long underwear womens - the ridge merino inversion heavyweight are some of the warmest long...
The Ridge Merino Inversion Heavyweight are some of the warmest long underwear bottoms that we've tested. While they are designed for the coldest months of the year, they were perfect for a little desert PT during our recent trip this fall.
Credit: Lindsey Fell

If you dig the ventilation panels and optimized breathability, the Icebreaker 260 ZoneKnit has a 100% Merino wool design, while the SmartWool Intraknit Thermal Merino Bottom features a blend of Merino wool and polyester that has enough structure to be worn on their own. 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 Ridge Merino Inversion.

Cold weather performance just got better with the Smartwool Intraknit.
Cold weather performance just got better with the Smartwool Intraknit.
We were happy to have the Icebreaker 260 ZoneKnit bottoms layered...
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.


The Patagonia Capilene Midweight Bottoms feature a 100% recycled polyester construction that we consider our cold weather workhorse. The synthetic Odlo Performance Light Bottoms are great for maintaining the heat generated during workouts and outdoor activities. However, they would not be a good choice for sedentary pursuits like hanging around a winter base camp or riding the chairlift. These bottoms perform best during more high-intensity activities during the cooler months of the year or when layered underneath insulated pants for Nordic skiing.

long underwear womens - the patagonia capilene midweight kept us warm while we kicked steps...
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 you're pushing the aerobic threshold or merely hanging out by the fire. To test breathability, we look at fabric thickness and type. We take each option backcountry skiing, hiking, climbing, and running in both warm and cold weather conditions. Finally, we evaluate the fabric to see if any moisture is retained within the fibers or if it's able to stay dry as a bone.


It's not surprising that 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 Air Bottoms, the Patagonia Capilene Thermal Weight, and Odlo Performance Light. Since the Thermal Weight and Capilene Air are rather see-through, we don't recommend them as stand-alone leggings. But their lightweight designs perform incredibly well in a layered system or with spandex bike shorts underneath.

long underwear womens - the lofted design of the patagonia capilene air bottoms makes it...
The lofted design of the Patagonia Capilene Air Bottoms makes it easy for air to permeate the layer and wick moisture away from the skin.
Credit: Trish Matheny


Bottoms like the Icebreaker 260 Zoneknit and the SmartWool Intraknit are perfect for backcountry or Nordic skiing when the temperature is decidedly cold (near to below freezing). Alternatively, the Odlo Performance Light is best for cooler weather (40 to 60 degrees Fahrenheit). If you're wondering about the difference between the Icebreaker Zoneknit and SmartWool Intraknit, it is mainly that the ZoneKnit is constructed from 100% Merino wool, while the Intraknit is a Merino wool blend. This difference in fabric affects warmth, breathability, and durability. As a result, we also recommend layering the Zoneknit rather than wearing them as a stand-alone pair of leggings.

long underwear womens - the odlo performance light bottoms are our favorite leggings for...
The Odlo Performance Light Bottoms are our favorite leggings for moving fast in cool to cold temperatures.
Credit: Toby Swimmer

The Patagonia Thermal Weight, Icebreaker Zoneknit, SmartWool Intraknit, and Odlo bottoms receive higher scores because they have special ventilation zones that target specific areas of the lower body which are prone to absorbing body heat and sweat. These body-mapped ventilation panels work well to promote airflow in these areas, offloading moisture while maintaining body heat.

long underwear womens - the ventilation panels located on the lower back, knee, and calf...
The ventilation panels located on the lower back, knee, and calf really enhance the breathability of the Icebreaker 260 ZoneKnit leggings.
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 and slim-fitting polyester fabric. On the trail, we prefer synthetics such as the Rho, which features a lighter-weight construction.

long underwear womens - moisture wicking capabilities made the rho one of our go-to&#039;s for...
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 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 that they lacked the ability to wick moisture away from the body, often resulting in sweat accumulating 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 days of the winter.

long underwear womens - the meriwool merino 250 bottoms feature a thick, midweight...
The Meriwool Merino 250 Bottoms feature a thick, midweight construction, perfect for rest days in the desert.
Credit: Lindsey Fell


Comfort and Fit


A long underwear bottom that'll feel cozy from the ski hill to your bed is the best you can hope for. Bottoms that fit correctly should also offer the highest level of comfort throughout an entire day of adventures. To test this metric, we put each bottom on, wore it all day, and recorded our experience.


The SmartWool Classic Thermal are quite comfortable. These bottoms are thick enough to keep you warm and provide enough coverage to be worn on their own; however, the fabric eventually sags throughout the day and doesn't have enough shape to hug 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, which features 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.

long underwear womens - the ultra fine merino wool construction of the ortovox 185 short...
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 fibers that are hollow, which can result 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, respectively, a brushed interior or Polartec fleece that's highly comfortable in addition to their superior, high-waisted fits. And, though not the warmest or most comfortable fabric in this review, the Odlo Performance Light Bottoms feature a great fit that is true to size and is soft against the skin, making them a great choice during cool weather activities.

long underwear womens - we love the stretchy fit of the patagonia capilene thermal weight...
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

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. The flattering fit of these bottoms is not only highlighted by this stylish waistband, but it is more comfortable next-to-skin and helps keep these bottoms in place.

long underwear womens - the ridge merino aspects features a stylish and flatting high waist...
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 a pair of bottoms only to find out that they fray, rip, and wear out after only a few uses. In order to measure overall durability, we observe wear and tear throughout our testing period until a new iteration of the product 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. Both the Midweight and Patagonia Capilene Thermal Weight offer a durable elastic waistband and flatlock seams, which inspire confidence in their construction — if only the odor treatment was as effective because these layers often smell after minimal use.

long underwear womens - the capilene midweight features durable and high quality flatlock...
The Capilene Midweight features durable and high quality flatlock seams that are built to last multiple seasons of extensive use.
Credit: Trish Matheny

We were perhaps the most curious as to how the Patagonia Thermal Weight and the Odlo Performance Light Bottoms would hold up during intense activity due to their see-through or ultra-thin designs. We are pleased to report that we have experienced no durability issues thus far, though the fabric is some of the thinnest that we tested, and we can't imagine it will last as long as a thicker and more rigid synthetic design.

long underwear womens - we love the odlo performance light for desert trail runs during the...
We love the Odlo Performance Light for desert trail runs during the fall.
Credit: Toby Swimmer

Another impressive bottom is the Arc'teryx Rho Bottom, which features a high-quality merrow stitch similar to a welded seam. The only issue that 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.

long underwear womens - we can appreciate the durable seams on the rho, strategically placed...
We can appreciate the durable seams on the Rho, strategically placed in high traffic areas prone to friction.
Credit: Trish Matheny

A thicker construction is seemingly more durable than a thin one. However, thicker contenders can also 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 it seems super burly even for its thinner construction. The Kari Traa Rose High Waist features a durable, thick, and well-made design reinforced with flatlock seams. Another impressive 100% Merino wool design is the Ridge Merino Inversion, which has held up to rigorous use well. Bottoms that integrate both Merino wool and synthetic fibers into their construction, such as the SmartWool Intraknit and Ridge Merino Aspect, also tend to hold up to wear and tear much better than their 100% Merino wool competitors.

long underwear womens - we experienced no durability issues with the kari traa rose high...
We experienced no durability issues with the Kari Traa Rose High Waist Pant, which features a high quality construction.
Credit: Trish Matheny

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 while in the backcountry for an extended period of time.


Our results revealed that the synthetic fabrics that feature a lightweight construction typically offer the fastest drying speeds, while the Merino wool layers typically require a much longer amount of time 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.

long underwear womens - the capilene midweight bottoms feature the fastest drying speed of...
The Capilene Midweight bottoms feature the fastest drying speed of all the layers that we tested.
Credit: Trish Matheny

Other synthetic options that offer fast drying speeds include the Patagonia Thermal Weight, the Arc'teryx Rho, and the Odlo Performance Light, drying in less than 45 minutes.

long underwear womens - if drying speed is an important performance metric to you, consider...
If drying speed is an important performance metric to you, consider these fully synthetic options.
Credit: Trish Matheny

Though most midweight Merino wool bottoms took longer to dry due to a thicker construction devoid of the porous structure of their synthetic competition, there were a few that stood apart from the rest. The SmartWool Classic All-Season Merino Bottom is notable here, as are the Icebreaker 200 Oasis Leggings. Of the thickest Merino wool bottoms, we suspect that the polyester blend aids in the faster drying speed for the SmartWool Classic All-Season and SmartWool Intraknit.

long underwear womens - the thicker merino wool fabric of the intraknit really slowed down...
The thicker Merino wool fabric of the Intraknit really slowed down the drying speed for these bottoms - they needed 65 minutes to completely dry.
Credit: Trish Matheny

Layering Ability


There is a lot to consider when evaluating the layering ability of each base layer. We tried to assemble a variety of different 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 Ridge Merino Aspect, the Icebreaker 200 Oasis, 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. We love the Icebreaker Oasis for its smooth wool fabric and low-profile elastic waistband, though we did notice some piling from some friction after skinning uphill. The Rock'N'Wool Short Pants offer the least amount of bulk in any layered system that 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&#039;t limited to the...
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...
The Ridge Merino Aspect bottoms feature a smooth interface that layered well below our jeans and offered plenty of mobility to climb in.


Our top-performing synthetic options include the Odlo Performance Light, REI Lightweight Base Layer Tights, and the Patagonia Capilene Midweight. The Odlo and REI options feature super low profiles and ultralight fabrics, which took up the least amount of space in our ski bibs, in addition to a very smooth interface between our puffy and rain pants. We love these options 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.

long underwear womens - the odlo bottoms are the perfect layer for spring skiing and easy to...
The Odlo bottoms are the perfect layer for spring skiing and easy to layer beneath your ski bibs for minimal bulk.
Credit: Trish Matheny

Another notable option is the SmartWool Classic All-Season Merino Bottom, which didn't impress us with durability, but 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, though it never reduced our mobility, especially considering it is the only heavyweight option in this review.

long underwear womens - though a heavyweight fabric, the merino wool of the ridge inversion...
Though a heavyweight fabric, the Merino wool of the Ridge Inversion is smooth, and the high rise fit reduces bulk around your natural waistline.
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 options to choose from, it's important that you take the time to select the piece 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 and that you stay warm and dry throughout the colder months of the year.

long underwear womens - the patagonia capilene thermal weight is the perfect layer for big...
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.
Credit: Trish Matheny

Trish Matheny, Amber King