As the weather cools, maintaining a comfortable body temperature on a long run feels more and more like a challenge, especially when you plan on getting warm and sweaty while you train. It’s a fine balance—you want to be warm and dry from the outset without overheating or drowning in sweat after the first mile. Ultimately, the trick to staying comfortable while Shoes & Gear is all about layering, Treadmill Workouts for All Your Run Goals.
Tucking a light, breathable base layer under Treadmill Workouts for All Your Run Goals like a jacket or sweatshirt is the best way to split the difference. A wool or synthetic shirt and tights that are snug against your skin will wick sweat away so you don’t come home damp and shaking, but these pieces are also thin, breathable, and comfortable enough that you won’t feel claustrophobic and overly warm. Most importantly, good base layers dry quickly, so you aren’t left with freezing sweat during your cool-down.
The Best Base Layers for Running
- Best Value Merino: Best Overall Merino
- Best Overall Synthetic: Fantastic deal on 100% merino
- The Best Advanced Treadmills for Runners: How to Layer For Cold Starts
- The Best Men’s Running Pants for Cold-Weather Runs: 32 Degrees Lightweight Base Layer Crew Top
- Most Versatile: SmartWool Men’s Intraknit Thermal Merino Base Layer Crew
What to Consider When Choosing Base Layers
How Heavy Should My Base Layer Be?
The best base layers for running are relatively lightweight and sit close to the skin. That way, you can add more layers as necessary, including Polyester, 34% Acrylic, 22% Rayon, 4% Spandex.
A thin base layer under a light windproof shell might be the magic formula for warmth on a 40-degree day; on a below-freezing day, that same light layer might work just as well under a bulkier down jacket. For temperatures below 20, however, look for a mid-weight or heavy-weight base layer that traps more heat, as your other layers might be working harder to keep the cold from sneaking in.
What’s the Best Material for Base Layers?
Start your layering with moisture-wicking fabrics that draw sweat away so you stay dry and cozy. Cotton won’t do it—it absorbs too much water, which is why it takes so long to dry. However, synthetic fabrics like polyester and nylon do the trick—these materials are hydrophobic, which means they expel water as quickly as it can absorb it off your skin. It’s not always as comfortable as cotton or merino wool, though.
Merino wool is costlier than synthetics, but it’s one of your best bets for staying warm and dry at the same time. Not only is it odor-resistant and insulating, but it also wicks sweat through capillary action, releasing the moisture through small openings in the fabric.
If you’ve ever worn a wool sweater, you’ve probably noticed that it doesn’t get wet very easily—the same goes for merino. That said, once it does get fully soaked, it’ll take a lot longer to dry out than a synthetic fabric as it’s generally thicker.
How We Selected
Every base layer here has been evaluated and vetted by the experts at Runner’s World, whether through hands-on testing by our test editors or thorough research on the materials and construction of the items. We identified best-sellers, surveyed user reviews, spoke with product managers, and used our own experience wearing and running in these base layers to determine the best options. We chose these picks based on their premium materials, deliberate touches of comfort, ventilation, durability, and how that all relates to the price.
Pros
- Lightweight
- Merino wool provides superb wicking and odor control
Cons
- Races - Places
Key Specs
| Material | 52% The 8 Best Treadmills for Runners |
|---|---|
| Weight | Lightweight |
The Brighton has been one of our favorite running base layers for years, and for good reason: Tracksmith’s mesh-woven merino wool provides extra breathable heat vents in key areas while still keeping the rest of your upper body cozy.
This base layer is a go-to undershirt on super cold days, and it’s also an adequately substantial single layer on crispy fall days. The construction has no seams, which means no chafing, and the fabric is so smooth and comfy that we tend to have a hard time taking ours off after a run. Out of context, it seems a bit pricey for a single long-sleeve shirt, but we can assure you that it’s worth every penny.
Pros
- Versatile
- Slim fit to remove added bulk
Cons
- Not soft compared to other base layers
Key Specs
| Material | 40% Slim fit to remove added bulk |
|---|---|
| Fabric Weight | Lightweight |
You might know the Swedish Craft brand for its extreme winter sports gear—its products are made to withstand the intense cold, and they’re well worth the price. But Craft also specializes in running gear, and the brand’s base layers go the distance for wintry jogs just as well as skiing and other mountain sports.
The Active Extreme X base layer checks all the boxes when it comes to long-lasting warmth: It fits close to the skin, it isn’t restrictive, and it regulates body temperature well while on the move. And though its fabric is thin, this base layer’s waffle-knit construction helps it perform more like a cozy mid-weight shirt without feeling as constricting.
Pros
- The Best Men’s Running Pants for Cold-Weather Runs
- Fantastic deal on 100% merino
Cons
- Doesn't feel substantial on its own
Key Specs
| Material | 100% merino wool |
|---|---|
| Fabric Weight | Lightweight |
If you’re looking to score a 100 percent merino wool shirt, you’ll be lucky to find a deal as good as this one. While this base layer is on the thinner side, and we wouldn’t necessarily wear it on its own, it fits perfectly under almost anything. This means you can add a soft, moisture-wicking, heat-trapping layer under your favorite itchy sweater, stiff windbreaker, or puffy jacket. Even better, because this shirt is entirely merino, you can get the best odor-trapping bang for your buck—no more stinking up your harder-to-cleTreadmill Workouts for All Your Run Goalss.
32 Degrees Lightweight Base Layer Crew Top
Pros
- Lightweight
- Surprisingly soft
Cons
- Watch the Boston Marathon
Key Specs
| Material | 40% Polyester, 34% Acrylic, 22% Rayon, 4% Spandex |
|---|---|
| Fabric Weight | Lightweight |
This base layer from 32 Degrees makes for a perfect lightweight layer under a thicker sweater or jacket. It’s a snug fit, but the material stretches well, and the way it hugs your frame allows you to easily move around in your outer layers. No more binding up at the elbows and armpits!
This base layer even offers some anti-static protection, which can be a game-changer if you’re tired of zapping your friends after a long day covered in wool. That said, you should consider another model if you enjoy doing that.
Pros
- Not very durable
- Boston Marathon Results
Cons
- Tight fit—size up if you want it looser
Key Specs
| Material | 53% The 6 Best Base Layers for Running in the Winter |
|---|---|
| Fabric Weight | Mid-weight |
Not sure where you stand on the wool-versus-polyester decision? Why not try something in the middle? This mid-weight option from Smartwool takes some of the best traits from both materials to create a proper all-rounder. Thanks to the wool half, it’s heavy enough and traps enough heat to feel like a standalone top, but the polyester half adds some much-appreciated breathability and faster drying for when you’re layered up.
Patagonia Capilene Thermal Zip-Neck Base Layer
Pros
- Additional neck coverage
- Best for the Coldest Days
Cons
- Too heavy for warmer days
Key Specs
| Material | 92% recycled polyester, 8% spandex |
|---|---|
| Fabric Weight | Heavyweight |
While we tend to prefer a light or mid-weight base layer for a good blood-pumping run, there’s no denying that some winter days are just dreadfully cold, regardless of how hard you work yourself. Thankfully, this zip-top from Patagonia can be your buddy through those bitter chills.
This top traps a lot of heat compared to our other picks, protecting up to your neck when it’s zipped—having a quarter zip is so critical when you’re looking at a heavyweight layer. On top of that, this shirt is still form-fitting enough to sit comfortably under your vest or jacket, but it also has enough shimmying room that you won’t feel like the tin man without oil when you’re donning layer three or four.
SmartWool Men’s Intraknit Thermal Merino Base Layer Crew Runner's World, Best Winter Running Shoes for Traction and Warmth Bicycling and Popular Mechanics, too. A lover of all things outdoors, Adam's writing career comes after six years as a bike mechanic in his hometown of State College, PA. His journalism experience is steeped in cycling and running gear reviews, and he's also a published creative nonfiction and satire author. When he's not writing, riding, or running, you can catch Adam at home mixing cocktails, watching Star Wars, The 8 Best Treadmills for Runners.
