Are you a woman in search of the best long underwear (base layer) bottom? We scoured the internet, researching over 70 different products, and bought 7 for head-to-head testing. We explored the world, skinning up mountains in Alaska and sailing the North Seas of the Faroe Islands. We hiked up steep slopes and ran over bush-laden trails. We put our hands and legs into cracks of the desert, then hunkered down for slumber while camping in cold weather. After months of in-field and in-lab testing, we've put together top recommendations and award winners to help you find your perfect next to skin layer.
The Best Long Underwear Bottoms for Women
|Price||$100.00 at REI|
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|$89.00 at REI|
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|$79.50 at REI||$78.00 at Amazon|
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|$35.40 at Patagonia|
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|Pros||Cozy and thick fabrics, huge range of thermoregulation, warm||Extremely comfortable, elastic and versatile fit, amazing value, cute and streamlined style, retains shape.||Warm, great thermoregulation, simple, great value||Durable, wide range of thermoregulation, comfortable, cute colors.||Durable, quick to dry, breathable, warm, high value.|
|Cons||Expensive, not super durable||High absorption of water.||Not durable, less cozy features||Not super duper warm.||Fabric holds moisture, not the most comfortable.|
|Bottom Line||This Editors' Choice provides unbeatable performance in the greatest range of conditions.||A versatile synthetic base layer that offers amazing style, performance, and warmth for all-day wear.||This is the best valued merino wool option out there.||This is the most durable merino wool contender out there.||This Best Buy award winner balances performance and value.|
|Rating Categories||Merino 250 Bottoms||Rho LT Bottoms||Merino Midweight Bottoms||200 Oasis Leggings||Capilene Midweight Bottoms|
|Comfort & Fit (30%)|
|Breathability & Drying Speed (30%)|
|Specs||Merino 250 Bottoms||Rho LT Bottoms||Merino Midweight...||200 Oasis Leggings||Capilene Midweight...|
|Material||100% merino||Torrent fleece (84% polyester, 16% elastane)||100% merino wool||100% merino||5.2-oz (176-g) Polartec® Power Grid® 97% polyester|
|Fabric weight (grams) & relative level of warmth||250 g (midweight)||150 g (midweight)||200 g (midweight)||200 g (lightweight)||176 g (midweight)|
|Measured Weight (oz)||7.2 oz||5.75 oz||5.95 oz||5.7 oz||6.15 oz|
|Fabric weights availiable||Lightweight (150), midweight (250)||Lightweight & midweight (AR) options||Midweight||Midweight||Lightweight, midweight, thermal weight|
|Cuts avaliable||3/4 length, full length, onsie (full body w/ hood)||Full length||Full length, boot length||3/4 length, full length||Full length|
|Smelly over time?||No||No||No||No||Yes|
|Odor control fabric||Naturally odor resistant||Polygiene® anti-odor finish||Naturally odor resistant||Naturally odor resistant||Polygiene® permanent odor control|
|Flat-lock seams (prevents chaffing)||Yes||Yes||Yes||Yes||Yes|
|UPF (Sun Protection)||No||No||No||No||No|
Best Overall Long Underwear Bottoms
Smartwool Merino 250 Bottoms - Women's
Balancing the best in warmth, comfort, and thermoregulation, this baselayer bottom will keep you warm while you travel from the cool to cold climates. It stacks 250-grams of 100 percent merino wool fibers that feels soft and cozy next to the skin. The fabric, being naturally odor resistant, withstands dirt and odors, making it a fantastic option for multi-day use (without a wash in between). All these excellent features, in addition to a versatile fit, make this piece our favorite long underwear bottom that we enjoy wearing all over the world. Use it on a cold day hike, car camping, or on your next backpacking mission.
Our only caveats live with durability and stretch. Since the fabrics are so soft, they catch easily on sharp surfaces and small holes can ensue. Also, after hiking or moving for a few hours, the material doesn't retain its stretch like a synthetic and stretches out. After a wash, the surface does bounce back though, allowing for cozy all-day wear. Snuggle up with a good book, or log the uphill miles in this fantastically warm, comfortable, and versatile long underwear bottom.
Read review: SmartWool Merino 250 Bottom - Women's
Best Bang for the Buck
Patagonia Capilene Midweight Bottoms - Women's
This is our favorite high-value option. This polyester contender stands out for its long-known durability and performance in cold weather. The midweight design provides ample warmth that varies from cool to cold weather. Don't be afraid to choose it as your primary piece of garb this winter. The synthetic fabrics dry out quickly when wet and because it uses polyester materials, it's seriously durable. Not to mention, the brick-like pattern provides breathability for your adventures that will have you sweating uphill.
Like most polyester fabrics, it can't regulate through as wide a range of temperatures as merino wool options. It readily absorbs water, and if there's no appropriate ventilation, this moisture can stay. As a result, it's not as warm as 100 percent merino wool options like the Smartwool Merino 250 Bottom. However, it is far more durable and will last you for many years to come.
Read review: Patagonia Capilene Midweight Bottom - Women's
Top Pick for Comfort & Versatility
Arc'teryx Rho LT Bottoms - Women's
A new love has flourished for this exceptionally stylish and comfortable piece of long underwear. The fabrics use a Torrent fleece that isn't only soft and comfortable against the skin but wicks away moisture well. The thickness is just right, providing fantastic breathability while offering supreme durability in the face fabric. The fit is versatile, extending enough leg length for taller women, and elasticity that bounces back, even after hiking to the top of a high mountain. With fabulous fabrics that have us wanting to curl up with a hot cup of cocoa on a cold day while crushing the skin track at the same time, we think it is worthy of a top pick for versatility. Not only that, but because of it's super cute colors and style, it, unlike other products, can be worn on its while climbing, hiking, or taking the dog on a walk.
It's hard to find anything wrong with this product. The only real downside is the expensive price tag and the inherent problems associated with synthetic fabrics. It absorbs water (when exposed to it), but dries would quickly. Aside from these quick issues, it's one of our favorites. We found ourselves making this our top choice garb when we truly wanted to be comfortable and cozy.
Read review: Arc'teryx Rho LT bottom
Analysis and Test Results
Every woman who gets outside in cold weather is in need of a solid long underwear bottom. Whether you're hiking, backpacking, or skiing, long underwear is meant to sit against your skin and wicks away moisture. If you find yourself hiking hard uphill, you'll begin to perspire. A great base layer needs to efficiently wick moisture from the skin. If it doesn't, it can condense when you slow down, ultimately keeping you cold. As a result, a great base layer is imperative to staying warm while you're active in cool to cold weather. In this review, we specifically focus on long underwear (aka baselayer) bottoms. We take a look a look at several great options currently on the market to give you feedback on our recommendations. Our review categorizes base layer bottoms primarily by the type of fabric and its weight. In our opinion, 100% merino wool is the best. But if you can't afford it, there are many other great options. Take a look to see what's out there.
While many expensive products reflect a higher value, that is not always the case. There are several products out there that provide similar levels of performance to the most expensive options. For example; the REI Co-op Merino Midweight Bottoms scores a similar score to our Editor's Choice winner and costs less. Also, synthetics are typically less expensive then Merino wool contenders in this review. Synthetics do not offer the same level of performance, but the fibers are far more durable…making them a better option for long-term wear and tear. The Patagonia Capilene Midweight Bottom is a perfect example.
Baselayers come in three different weights that indicate the relative level of warmth. This includes lightweight, midweight, and heavyweight. During our testing period, we performed a few tests. First, we observed the different fabrics and make-up of each product. We read reviews and learned about what others had to say. Then, we took each bottom around the world. We tested warmth while getting splashed by cold waves in the North Sea, slept under the stars of the desert, and hiked up fourteen thousand foot mountains. Not only that, but we masochistically decided to sleep outside of our homes when the temperatures dipped into the sub-zeros…just to see how each product performed side by side.
After our tests, we observed and analyzed a few key patterns. To make it simple, Merino wool rules over synthetics. The natural organic fibers don't only feel good against the skin but offer a much wider range of thermoregulation. It dumps heat more efficiently when you begin to sweat and will insulate better when the temperatures begin to drop. The fabric is able to evaporate moisture more readily when ventilation isn't present, doing a better job at moving moisture away from the skin. This inherently makes the long underwear bottom warmer in the long run…especially after wearing for many days on end through periods of sweating and sitting.
Basically, any long underwear that is constructed of 100% merino wool will serve you well. The key to deciphering between the warmest and coolest options is weight. For example, our Editor's Choice winner, the Smartwool Merino 250, provides the most warmth of any contender tester. It features 250-grams of material and the fabric is obviously thicker then other contenders like the REI Co-op Merino Midweight Bottom that only has 200-grams of 100% Merino wool. This warmth is inherently due to the thicker fabrics and the bomber wicking power offered with the Merino Fabrics. The Icebreaker Oasis Leggings performs similarly to the REI Merino Midweight bottom, also offering 200-grams of warmth (with some cute colors and patterns). Both the Icebreaker and Oasis have a similar weight as well. Through all of our testing periods, all these contenders performed well in a layered system to wick away moisture, with the Smartwool 250 Bottoms offering the most warmth.
If a synthetic blend is what you seek, the Arc'teryx Rho LT bottom, our Top Pick for Versatility and Comfort stands above the rest. The Torrent fleece (made of 84% polyester and 16% elastane) features a super soft fiber that doesn't only offer uber amounts of comfort but provides insulation and wicking power than other synthetic contenders. While sleeping out in sub-zero temperature, we were warm and cozy in our sleeping bags. Another nice and warm synthetic option is the Patagonia Capilene Midweight Bottom, offering 176-grams of 100% polyester comfort. Even though the Capilene has more in the way of weight, the Rho LT provided a little more heat in the field. This is mostly because the fleecy fabric make-up has tiny little arm-like projections that stick out (on a microscopic level) to more efficiently capture heat and wick away moisture. The Capilene, on the other hand, has less of these mini fibers and has less affinity to do so. As a result, it seems that the Rho Lt offers more in the way of warmth.
If you prefer a long-underwear bottom that doesn't insulate hugely, consider a lightweight design. These options are best for warm to cool weather, or while being active in cool weather. The sole purpose of these pieces is to wick away moisture without the added bulk of insulation. A great merino wool option is the SmartWool Merino 150 Bottom, made of 150-grams of a Merino wool blend (87% merino wool, 13% nylon core). This blend adds wicking power, while the wool keeps the skin warm and happy. If synthetics are what you prefer, take a look at the ultra thin REI Co-op Lightweight Base Layer Tights, which offer wicking power and not a whole lot in the way of insulation.
Comfort and Fit
Want a pair of long underwear that will feel cozy and comfortable while you charge hard all day long? You're going to make sure it fits if you do! While testing this metric, we considered many important questions. What are the materials? Does it feel soft or scratchy against the skin? Are there any points of chaffing or constriction when putting it on? Does it still feel good against the skin when wet? Can it be worn for a few hours, a day, or many days comfortably without washing? Is the fabric stretchy? Does the fabric stretch out after a few hours or wear?
In order to test these question, we wore each bottom every single day through our testing period. We went to work with them under a tight pair of jeans. We skinned up Red Mountain pass in the San Juans, layering each underneath a pair of snow pants. We also wore each to bed and just hung around the house to see how the fabrics felt. With this newfound knowledge (and additional online research) we determined which bottoms are the most comfortable and which ones simply are not.
Earning a perfect score in this category is the Arc'teryx Rho LT hosting the softest and most comfortable fabrics in this review! The Torrent fleece is a unique fabric blend that offers both a cozy feeling on the skin and a stretch in its fit. Our testers agreed that it seems more comfortable than merino wool contenders. While running up Uncompahgre Peak (a Fourteener in Colorado), this fabric kept us cozy and dry. In addition, the elastane integrated into the fabric helped to retain its shape, even after being in motion for hours. No other product showed this level of shape retention. In addition, the fit is versatile, offering great lengths for both short and long-legged ladies.
Aside from Arc'teryx Rho LT, synthetics are typically not as comfortable as Merino wool fabrics. These luscious fibers found in 100% merino wool contenders like the Smartwool 250 and REI Merino Midweight are super soft and continue to feel amazing against the skin both when wet and dry. The Smartwool 250 earns top points in this arena because the fabrics aren't only soft, but they are thick. Its face fabric is slippery, making layering easy, while the waistband offers an extra layer of fabric that adds to its comforts. The REI Merino Midweight and Icebreaker Oasis earn a solid score as well, but because the material is thinner, and the waistbands aren't particularly special, we don't consider it as comfortable. Another note we made with these contenders is that they continue to stay comfortable and cozy, even after being sweat in for days on end. You'd be hard-pressed to find a synthetic option that exemplifies this.
Of the lightweight contenders, the SmartWool Merino 150 Bottom has fabrics that are a touch thicker, constructed of 100% Merino wool. As a result, its way more comfortable and our top recommendation if you seek a thinner merino wool option with awesome comfort and fit.
Breathability & Drying Speed
Breathability and drying speed work together to ensure that your long underwear stays dry, whether you're pushing the aerobic threshold or simply hanging outside. To test breathability, we looked at the thickness and type of fabrics. In addition, we took each piece running (without an overlayer) to determine how the fabric allows sweat to wick away from the body. After our sweaty runs, we looked at the fabric to see if moisture retained in the fibers, or if it easily evaporated away. To test drying speed, we performed some dryer tests where each piece was comparatively wet down, then dunked and agitated, then put into the dryer. We then calculated the water absorption and the rate of drying to determine which products scored highest in this metric.
The results? Thinner fabrics (synthetic or merino wool) are simply more breathable then thinner fabrics. The thinner materials allow air to pass through more readily, thus allowing evaporation. For example; of the Merino wool contenders, the SmartWool Merino 150 Bottom provided the best breathability. This is in part to the lesser amounts of materials found in the construction…that said, in our dryer tests, it didn't dry as quickly as other more absorbant contenders like the Smartwool 250 and REI Merino Midweight bottoms that lost water more readily (probably because there was more water to lose!). As a result, they have a similar score in this metric.
Our synthetics contender, the REI Co-op Lightweight Base Layer Tights, provide a great level of breathability overall. We'd recommend wearing these for getting your heart rate up on cold days. The fabric easily breathes, wicking sweat and transporting it away from the skin.
Thicker contenders don't breathe as well as thinner alternatives, and they do absorb a lot of water. In fact, while Merino wool repels water longer than synthetic options (that readily absorbs it), merino will hold much more water. In our tests, rates of drying were pretty high, but not as fast as the Patagonia Capilene Midweight Bottom. It absorbed 11.3 oz of water (just a little less than the Smartwool 250 Bottom) but dried out a little faster than Merino wool contenders. While this is an interesting point to make, the drying times were not very different in our tests, and the differences seemed to be minute. Another important thing to note is that while the Capilene (midweight) showed a high drying speed (along with all contenders), in our field tests, we noticed that moisture locked itself into the fabric more readily then Merino wool contenders. As a result, we'd say that Merino wool is better at drying in general, but it, unfortunately, absorbs more water once it's been agitated.
If you seek a breathable layer, you're in luck! All the pieces in this review breathed and dried effectively. If you want the best in this category, look for thinner constructs and merino wool fibers for better wicking and drying power overall.
Ensuring that your long underwear bottom is durable is key to buying a high-value product. To test durability we simply observed wear and tear after our testing period. We hiked, skied, climbed, and ran with each, both layered and on its own. We also evaluated the quality and craftsmanship of every product by looking at its seams and stitching. After walking through bramble bushes and thrashing each while crack climbing, we got a pretty good idea of which products are more durable than others.
Synthetics and blends definitely trump Merino wool when it comes to this metric. The strong fibers, such as those found in our Best Buy award winner, the Patagonia Capilene Midweight Bottoms, are literally bomb-proof. Through our testing, we encountered snags and drags, tugging at the fabric. Whereas a little hang-up with a nail caused the Smartwool 250 Bottoms to tear super easily, the Capilene proved to be much more resilient. Our main tester has owned the Capilene brand for many years, with it proving to last. Upon just a couple of months with the Smartwool, we observed tearing (when snagged) after just a short period of time.
In addition, fabric thickness is something to consider as well. Typically thicker fabrics will provide a better level of durability. For example, the Arc'teryx Rho LT bottom scored really high in this metric. It hosts thicker fabrics that are tightly knit to give it a continuous feel. As a result, it's durability far surpasses merino wool options. It's also worth mentioning that the Rho LT bottoms also proved to have the best craftsmanship with tightly sewn seams and fabric that didn't pill, even after numerous washes.
Overall, the most durable base layer bottoms are those constructed of 100% polyester materials. While Merino wool provides some form of resilience to wear and tear, it is more susceptible to wear and tear. If you seek durability as a priority, synthetics, and specifically the Patagonia Capilene Midweight bottom should be your top choice.
Every outdoorswoman needs a bomber base layer bottom to wick away moisture when combating tumultuous terrain in the cold weather. If you are looking for the best when it comes to performance, Merino wool is the way to go. It's warm, thermoregulates well, doesn't stink after a long period of time, and provides cozy comforts on the skin. However, if you prefer a piece that amps up its wicking power and durability, synthetics may be your go-to. Whatever you need, make sure to order a few different options, try them on, and keep the ones you like. We hope this article has helped you in your search for a key piece of gear that should last you for many adventures and years to come.
— Amber King