“There’s no such thing as bad weather, only unsuitable clothing,” at least so sayeth Alfred Wainwright in his 1973 book Coast to Coast, and surely he had base layers in mind when contemplating clothing systems. The best base layers for women will keep you warm, dry, and comfortable, and you can wear them as a stand-alone layer or as a base for additional insulation.
We sought to compile a versatile list of products that would be useful for different groups of women. Our testing started by narrowing our testing pool down to options from 10 brands and taking them out in all types of climates, from the San Juan mountains of Colorado to the high deserts of Utah to western North Carolina. We selected both wool and synthetic layers, and we also paid attention to some budget-friendly options. Some of these base layers are old familiars, and a couple are from newer companies. Our goal was to help you choose the best base layer for your needs.
At the top of the list is Patagonia’s Women’s Capilene Air Crew, followed closely by Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve, lightweight enough to layer or stand-alone and with excellent wicking capability. The Oiselle Flyout Long Sleeve held down the super lightweight category.
Best Base Layers for Women
- Best Overall Base Layer: Patagonia Women’s Capilene Air Crew
- Best Base Layer – Runner-Up: Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve
- Best Base Layer – Runner-Up: Janji Repeat Merino Long Sleeve
- Best Budget Layer: Under Armour Women’s HeatGear Compression Long Sleeve
- Softest Base Layer: Paka Women’s Everyday Base Layer
- Best Ultralight Base Layer: Oiselle Flyout Long Sleeve
- Best Base Layer Tights: CEP Compression Run Tight 4.0, Women
Best Overall Base Layer: Patagonia Women’s Capilene Air Crew ($139)
- Great fit
- It doesn’t pick up odor
- Hefty price tag
- Possible snag-ability
With a seamless 3D-knit structure, the Patagonia Women’s Capilene Air Crew boasts excellent warmth and is many runners’ go-to cold-weather base layer. This base layer uses merino wool from New Zealand that is blended with Capilene, a recycled polyester, for enhanced warmth balanced with excellent wicking, durability, and drying time. Its slim fit offers comfort without feeling restrictive, and its seamless structure means it’s less likely to rub or cause chafing during long runs under a hydration vest or in wet conditions.
This layer deserves credit for its ability to resist odor, substantial wicking prowess, and remarkable ability to dry quickly. It also has an average UPF rating of 34 to provide sun protection. Testers tout its warmth and breathability as reasons for this being their favorite layer. Longtime wearers of this base layer also note that it’s pretty durable and able to withstand months (and years!) of long runs without becoming too worn. Chances are if you are running or racing in chilly weather with a group, at least one of them will be wearing this layer and will tell you how much they like it and its versatility. Many of the testers for this guide have been using this base layer for years.
Patagonia remains committed to its environmentally friendly practices, and the wool for this base layer is responsibly sourced. The main drawback to this product is its price tag, which is hefty.
Material: 51% responsibly sourced merino wool, 49% recycled polyester | Fit: Slim | Actual Weight: 5.2 ounces (147 grams)Shop the Patagonia Women's Capilene Air Crew
Best Base Layer – Runner-Up: Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve ($90)
- Wicks well
- Odor resistant
The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve has been a staple in many runner’s chilly-weather arsenals for a long time and with good reason. It’s lightweight and not bulky, so it can easily be layered under heavier items in freezing weather, but it is substantial enough to wear alone.
It features Core Spun technology, consisting of merino wool fibers wrapped around a nylon core. This adds durability to the material while keeping the comfort and wicking properties of ultra-soft, responsibly sourced merino next to the skin. The raglan cut on the sleeves means hydration vests don’t cause friction on the shoulders, and the merrow stitching down the sleeves is super-smooth, reinforced, and very comfortable.
The high merino wool content means this layer can be washed less frequently, adding to shelf life, as it repels odor-causing bacteria. This top dries quickly, so rinsing it during multi-day fastpacking trips is no big deal.
One tester experienced a hydration bladder leak while running up Mount Leconte in Great Smoky Mountains National Park in Tennessee and noted that the layer kept her warm despite being soaked all down the back.
This layer is available in a variety of color choices and sizes and is also available as a ¼ zip top if you want to have the option of additional venting.
Smartwool uses ethically sourced and recycled wool practices to reduce the environmental footprint of their products.
Material: 88% merino wool, 12% nylon | Fit: Slim | Actual Weight: 5.3 ounces (150 grams)Shop the Smartwool Women's Classic All-Season Merino Base Layer Long Sleeve
Best Base Layer – Runner-Up: Janji Repeat Merino Long Sleeve ($88)
- Recyclable packaging
- Best for cool or transitional weather
Choosing the best base layer for women was a difficult task, and the Janji Repeat Merino Long Sleeve scored high in many categories for many of our testers. This ultralight layer has a tee-shirt-type fit and was a favorite for chilly and transitional weather. Testers noted that it was a comfortable layer for runs that start cold but gradually heat up, as it isn’t overbearing in its warmth level. The thumb holes at the end of the sleeve made it easy to get a little bit of extra protection over the hands, and it also kept the sleeves from riding up when we put an extra layer on over it.
The merino is Responsible Wool Standard (RDS) certified, and the nylon is bluesign certified, meaning it is free from harmful chemicals and is fabricated in a way that meets a high environmental standard. The blend of nylon and wool makes for a durable material that maintains all of wool’s moisture-wicking and odor-control properties. It is also quite breathable; we could wear it multiple times between washes.
Janji has a clearly stated environmental mission and is part of the 2% for Clean Water program.
Material: 47% RDS-certified merino wool, 53% nylon | Fit: Tee-shirt | Actual Weight: 9.9 ounces (282 grams)Shop the Janji Repeat Merino Long Sleeve
Best Budget Layer: Under Armour Women’s HeatGear Compression Long Sleeve ($35)
- Wicks well
- Great value for the price
- Not the most breathable
- It felt too tight in places on some testers
If you want a base layer that will keep you warm and doesn’t come with a large price tag, the Under Armour Women’s HeatGear Compression Long Sleeve is a great choice. It’s an approachable, readily available, and budget-friendly option, and this lightweight layer did not disappoint. It’s made of the brand’s HeatGear fabric, a four-way stretch material, and the flatlock seams offer a chafe-free fit.
This is a compression top, and some people might not like the tightness of the fit. The science on using compression clothing for performance improvement is inconclusive, but many people like the support and feel of it, especially during longer runs where all parts of the body start to hurt by the end. If you’re not into the compression, consider sizing up.
Testers report that this layer wicked relatively well and was bearable even up to 55 to 60 degrees Fahrenheit, but it wasn’t ideal for those temperatures. They also noted that although this is a synthetic layer, it offered excellent odor resistance.
Material: 87% polyester, 13% elastane | Fit: Compression tight | Actual Weight: 5.0 ounces (143 grams)Shop the Under Armour Women's HeatGear Compression Long Sleeve
Softest Base Layer: Paka Women’s Everyday Base Layer ($75)
- Amazingly soft
- Nice appearance
- Warm yet wicking
- High price
- Long-term durability not yet determined
The Paka Women’s Everyday Base Layer scored high among testers with its soft texture and comfortable fit. This base is a blend of alpaca wool and Tencel, making for a durable and soft material. The top is very lightweight with a sort of body-skimming, almost liquid texture, but it offers lots of warmth, especially for how light it is. Testers scored it highly on fit, breathability, and drying time, and we found it to work well solo and underneath outer layers. We also liked that this item was nice enough to be worn as an everyday piece of clothing, and it became a staple for casual wear in addition to being a functional piece of gear.
Unlike many of the brands included in this guide, Paka is relatively new to the market, so we’re unsure if this base layer will last as long as others we’ve used for years.
We appreciated Paka’s transparency and sustainability practices. They use compostable packaging to ship their products, and consumers can trace garments to the exact coordinates where fiber for their item was sourced.
Material: 80% Tencel, 20% Royal alpaca | Fit: Casual | Actual Weight: 4.9 ounces (139 grams)Shop the Paka Women's Everyday Base Layer
Best Ultralight Base Layer: Oiselle Flyout Long Sleeve ($76)
- Watch windows
- Not incredibly warm
When you want a light base layer for those shoulder-season chilly but not cold runs, the Oiselle Flyout Long Sleeve has a lot to offer. Oiselle uses its proprietary Flyout fabric with HoverFit technology. They claim the material can hover above the skin, helping with heat and water transfer. We found that this layer does indeed breathe well.
Oiselle is a brand that offers gear made specifically for active women’s bodies, and items are available in an inclusive range of sizes. The raglan design helps to eliminate seams chafing around the arms and shoulders, and testers commented that this layer boasts an ultra-soft hand feel. We loved the thumb holes that kept the sleeves down and warmed our hands, and we also appreciated the watch window, which allowed us to keep an eye on our splits and pace without having to roll up our sleeves.
Oiselle seeks to source materials responsibly and upcycled materials to reduce waste with their Fabric Forward Program.
Material: 65% polyester, 32% Tencel, 3% spandex | Fit: Skin tight | Actual Weight: 3.8 ounces (109 grams)Shop the Oiselle Flyout Long Sleeve
Best Base Layer Tights: CEP Compression Run Tight 4.0, Women ($150)
- Perfect compression level
- Warm yet breathable
- Compression might not work for some runners
If you regularly wear compression socks or calf sleeves, the CEP Compression Run Tight 4.0, Women are a great cold-weather alternative. Whether you wear compression clothing for all of your runs, just for racing or long training runs, or for recovery, these tights provide a high level of support in a warm package. These compression tights are high-waisted with no side seam, have a cord drawstring with anti-slip coating, and have a large back pocket. These tights ranked high for staying where they are supposed to, meaning no stopping to hike them up or adjust leg seams. The design includes mesh in places, which helps minimize the chance of chafing and increases breathability. These tights are not lined with additional insulation but are substantial enough to keep legs warm on cold runs.
Material: Compression – 58% polyamide, 42% elastane, Mesh – 84% polyamide, 16% elastane. | Fit: Compression tight | Actual Weight: 6.0 ounces (172 grams)Shop the Compression Run Tight 4.0, Women
Comparing the Best Base Layers for Women
|Patagonia Women’s Capilene Air Crew
|51% responsibly sourced merino wool, 49% recycled polyester
|Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve
|88% merino wool, 12% nylon
|Janji Repeat Merino Long Sleeve
|47% RDS-certified merino wool, 53% nylon
|Under Armour Women’s HeatGear Compression Long Sleeve
|87% polyester, 13% elastane
|Paka Women’s Everyday Base Layer
|80% Tencel, 20% Royal alpaca
|Oiselle Flyout Long Sleeve
|65% polyester, 32% Tencel, 3% spandex
|CEP Compression Run Tight 4.0, Women
|58% polyamide, 42% elastane
Buying Advice: How to Choose Base Layers for Women
When trying to find the best base layer for women, there are many details to consider, including where you’ll be running. Is the climate dry or humid, or will you likely sweat or stay dry? How cold will it be? Will you be exposed to the sun and require UPF protection? Does the layer need to fit under several more layers for warmth, or will you wear it as a stand-alone layer? All these factors come into play when choosing the right base for your run. Our team found that the Patagonia Women’s Capilene Air Crew was the right mix of all the factors, making it a great base layer.
When considering fit, weigh what you will wear on top of your base layer. A base layer can be a stand-alone garment for some climates or transitional weather. Some of the layers we tested were perfect for chilly weather and had a looser fit for ease of motion and comfort. The Paka Women’s Everyday Base Layer was reported to have one of the softest and most comfortable everyday fits, but its body-skimming cut might not be ideal for layering.
The compression layers in this guide, including the Under Armour Women’s HeatGear Compression Long Sleeve, are designed to fit very tightly, and there are several skin-tight layers in the guide, as well, like the Oiselle Flyout Long Sleeve, that are tight, but not compression-tight. A tighter layer can be a little less bulky, which some runners prefer, especially if they seek warmth from a mid-layer on top of their base. Additionally, compression layers promote blood flow and oxygenation to muscles and can be used to support fatigued muscles.
Seam size and location are important. Many of the layers we tested featured a raglan-style cut to eliminate the seams around the shoulders and had specialty stitching in other places to reduce the possibility of chafing. The Janji Repeat Merino Long Sleeve combines merrow stitching and thumbholes that function well to keep things in place on long runs and under hydration vests.
Traditionally, many runners have turned to merino wool for their base layer. Merino wool is known for being insulating, even when wet, and for helping regulate temperature by controlling the rate of moisture evaporation from the skin. It is extremely breathable due to the porosity of the fibers and you can stay dry even as you sweat. As far as warmth for the buck, merino will do a great job of keeping you insulated from colder temps. A lightweight merino or merino-blend base layer is an excellent option for cooler temperatures, while a mid- or heavyweight merino will keep you toasty in the coldest climates. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve has a very high merino content, meaning it keeps runners cozy in all conditions and offers warmth and breathability even while wet.
Regarding sustainability, runners will have to weigh where they stand on the ethical implications of using resources to raise livestock and the effect on climate change, as well as using animal products in clothing.
If you’re vegan or searching for more budget-friendly options for your base layer, look to synthetics. Typically, a polyester or polyester-blend base layer will excel at wicking and keeping you super dry. Synthetic base layers are available in a variety of fits, including compression. They often have a tighter fit, which is excellent if you want to add layers on top for warmth or weather protection. Because of their wicking capability and quick-drying attributes, synthetic layers will minimize chafing and keep you from overheating. While not overly budget-friendly, Oiselle’s Flyout Long Sleeve checked the boxes for our vegan runners and those who preferred synthetic fabrics to wool.
Generally speaking, you’ll want to choose the layer that will best fit most of your running circumstances. Lightweight layers are best for moderate to cool temperatures and runs that might begin in chillier weather that warms up during the day. Midweight layers are effective for cold temps, and heavyweight layers are for those frigid below-freezing runs. One thing to consider is that the main job of a base layer is to keep the wearer comfortable and dry. Additional warmth is almost always determined by what’s worn on top of the base, including the outer layers. Finding the most comfortable and wicking base layer against your skin is paramount. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve was lightweight enough to act as a base layer, and we found that its ¼-zip cousin worked great as a mid-layer that can be unzipped to vent. Most layers tested for this buyer’s guide were lightweight or midweight options.
UPF stands for ultraviolet protection factor, and some base layers carry a tag with a UPF rating for sun protection. The UPF rating refers to how much UV the fabric of the garment blocks. In general, a darker-colored fabric will offer more UV protection, as will a fabric with a tighter, denser weave. Synthetic materials like polyester provide more protection than natural fibers like merino, and a looser fit offers more protection than an item stretched tightly across the skin. If your runs take you to environments that have you open and exposed to the sun’s rays, UPF protection is important for keeping you safe. If you’re at a higher elevation, have sun-sensitive skin, or are taking medication that makes you vulnerable to the sun, a UPF rating may be important to consider. Not all base layers offer a UPF rating, and garment makers have their own testing protocols. Patagonia devotes a page of its website to explaining the intricacies of UPF, which is another reason the Patagonia Women’s Capilene Air Crew came out on top in this guide.
Arguably, breathability is one of the most important aspects of a base layer. There’s nothing worse than being drenched in sweat or precipitation and feeling like you can’t escape it. Material, weight, and openness of the weave all contribute to a layer’s breathability. Lightweight merino and synthetic base layers tend to be more breathable than heavier ones. Merino, in particular, is known for its thermo-regulating properties, as it has superior wicking capability while also keeping you warm even when wet. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve offered a great warm and breathable merino layer, while the HoverFit technology of the Oiselle Flyout Long Sleeve made it score high on the breathability scale for synthetics.
Merino wool is the clear winner in stinkiness prevention. The wicking nature of merino contributes to its odor-resistance. Because it stays dry, allowing water to evaporate before it soaks the material, there’s less chance for odor-causing bacteria to flourish, thus less funkiness caused by microbes. Merino layers don’t need to be washed as often, and any time you can get more than one run from a layer is a win. Our testers could run in Smartwool’s Women’s Classic All-Season Merino Base Layer Long Sleeve and in the Janji Repeat Merino Long Sleeve for several back-to-back outings with nary a wash or rinse.
Many of the base layers on the market require shelling out a little bit of dough, so of course we want these items to last for as long as possible. Another plus for merino or merino blends is that they reduce odors, so they need to be washed less frequently. Less frequent washing can extend the shelf life of a garment. We recommend air-drying base layers, especially wool ones, which should never be put in the dryer, to help extend their lifespan as well.
Several team members have owned Patagonia’s Women’s Capilene Air Crew for years and have been impressed with its long-term durability. For trail runners in particular, items tend to get put through the wringer as we can encounter narrow singletrack, which can increase the possibility of snags and tears, so we want materials that can stand up to use.
Having to replace items frequently has an environmental impact, but more on that later.
When choosing the best base layers for women, consider climate and environment. Ideally, we want to select the lightest and most functional base layer for that day’s effort. Base layers can be lightweight for cool to chilly weather, midweight for cold weather, or heavyweight for extreme cold. Additional warmth can be provided by a mid-insulating layer and top shell, depending on conditions, so there’s no need to try to have the base layer be the only layer in harsher weather. The Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve is a classic base layer that works well in chilly temperatures but can be worn under extra layers as temperatures drop.
There are many styles to choose from in the world of the best base layers for women. Some are available in short-sleeve lengths as well as long sleeves. Our runner-up, the Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve, is available in a crew form and a quarter-zip option. There are several base layers on the market now that also have hoods.
Within this testing, the Paka Women’s Everyday Base Layer ranked high in the style category, with runners commenting that the layer is so nice looking and dries so quickly that it easily goes from run to town. It’s likely to double as a non-running item in many closets as well.
Many runners tend to be relatively conscious consumers, so considering sustainability is a great way to narrow down choices when making an investment. Some issues to think about when choosing a garment are the manufacturer’s factory emissions, including gas emissions and anything that may eventually end up in a water source, whether producers and plant workers are compensated fairly, how raw materials are sourced, and how the company as a whole gives back to our community and our world.
In the group of products we chose, almost all of the merino used was ethically sourced and certified by a third-party organization. Depending on animal conditions, merino can be considered eco-friendly as it consists of proteins and amino acids and eventually naturally breaks down in water and soil.
We are also impressed by companies using recycled packaging. Patagonia, Smartwool, and Janji were all standouts in this area, and Paka took it one step further with their Paka Women’s Everyday Base Layer by using compostable packaging and a system that allows one to trace the fibers in their garment back to their source via their website.
Why Trust Us
For this guide, we tested ten different brands of base layers. Women from all over the country, including Colorado, Utah, Tennessee, and North Carolina put these layers through their paces in a variety of environments, elevations, and weather conditions. We tackled the trails, ran roads, and crushed some gravel. We used the base layers in colder climates and some warmer weather to test breathability and wicking capabilities. We referred to some of our old familiar products that we know and love, and we threw some newcomers and outliers into the mix to narrow our list down to the best base layers for women.
We routinely update our buyer’s guides based on ongoing testing and research by our authors and editorial team. Our goal is to find the best products on the market so that you can run your best.
Frequently Asked Questions about Base Layers for Women
What makes merino wool a good base layer material?
Many of the best base layers for women are made of merino wood. This fabric has the unique property of allowing water vapor from your skin to evaporate before it turns into water droplets. This comes from the porosity of the fibers and helps them stay dry while wicking moisture away from your skin. Merino wool, such as that used in the Smartwool Women’s Classic All-Season Merino Base Layer Long Sleeve, also insulates even when wet and helps regulate temperature by controlling the evaporation rate. That, combined with the odor-resistance of this material mentioned above, means it stays fresh longer between washes. It dries exceptionally quickly when washed or wet with precipitation or sweat. Washing less frequently adds to the shelf life of the layer.
What is the best type of base layer for running?
The best base layer for women will be the lightest and most comfortable while still meeting the needs of the runner’s climate and environment. Merino seems by far and away to be the frontrunner, but several synthetics and blends that also offer warmth and strong wicking performance are available. Our team loved the Patagonia Women’s Capilene Air Crew and named it the best overall base layer for women.
What are the best types of base layers for extreme cold?
For extremely cold conditions, it might be necessary to choose a heavyweight base that’s absolutely going to perform with superior wicking capability. Generally speaking though, midweight base layers, like the heaviest layer we tested, the Patagonia Women’s Capilene Air Crew, used with other layers will get most runners through most conditions. Remember, the main job of a base layer is to move moisture away from your skin without getting wet, so a really heavy base layer might not be the best option.
Are there warmth ratings for base layers?
Base layers can be lightweight, made for cool to chilly weather, midweight for cold weather, or heavyweight for the most frigid conditions. Additional warmth can be provided by adding extra layers on top of your base layer. Choosing the lightest, most comfortable, wicking layer for the conditions should keep you ready to run for all the miles. A lightweight base layer like the Janji Repeat Merino Long Sleeve is a great starting point for adding extra layers.
Call for Comments
- Do you frequently use a base layer for running?
- What’s your favorite base layer?
- How do you like to layer on top of a base layer?