It all starts easily enough—you read a profile of a prolific Olympic skiier, or maybe you see an Instagram post of a cozy chalet in the mountains. Next thing you know, you're googling, "what's a base layer" and researching winter hiking destinations in Colorado.
While we love the outdoor opportunities that summer allows, there's just as much to do outside in the winter season—but having the right clothing makes all the difference. The trick to staying warm lies in having the right base layers. And the good news is: they don't have to cost a fortune!
Here's what to know about base layers to keep warm this winter, whether you're lounging aprés or out on a multi-mile hike:
What's a "base layer", and why are they important?
Base layers are the layer of clothing closest to your skin, and they play an important role in temperature regulation. They're designed to keep heat in while wicking sweat away from your skin, which is critical to staying comfortable and warm when you're switching between hot indoor spaces and cold outside climates, or doing outdoor winter activities.
Base layers come in both tops and bottoms, and are meant to be fitted close to your skin.
Do I need base layers?
In the winter: yes! Base layers are important because they provide an extra layer of insulation while also wicking sweat away from your skin. If you'll be going from hot to cold throughout the day, or doing any activity where you might be sweating in a colder environment, you should definitely opt to wear base layers.
What should I look for in a base layer?
Look for two things:
A close fit. You don't want your base layers to be loose, because they're intended to act as an insulating layer. Having a loose base layer might allow cold air to circulate near your skin, which defeats the purpose of the layer.
A moisture-wicking material. Good base layers are made from synthetic, wool, silk, or bamboo fibers—more on each option below. Avoid cotton, which takes too long to dry and pulls heat away from the body, which will leave you cold and uncomfortable.
What is better—synthetic, silk, wool, or bamboo?
It depends on what you're looking for! Most base layers are made from synthetic, silk, or wool. There are also new base layers being made from bamboo, which is a great vegan alternative or an option for those whose skin is irritated by wool fibers. Here's a quick primer on each:
Synthetic base layers are often cheaper, which makes them an appealing starter option. The downside to synthetics is that they aren't naturally anti-microbial, so they can get a bit stinky after a while. They also aren't as good at insulating heat, so they might not be the best choice for really cold climates.
Choose a synthetic base layer if... you're headed to a milder climate, you're a beginner, or you're doing a sweaty activity. A good choice if you are trying out winter climates for a weekend, but not ready to invest in pricier materials.
You might be surprised to hear that silk is a great base layer for winter! The benefit of silk is that it is super lightweight and not bulky, while still acting as an effective and naturally wicking insulating layer. The downside here is cost and care, but a well-cared-for set of silk base layers can last you for years.
Choose a silk base layer if... you want an inconspicuous but warm base layer that works well under other clothing, and are willing to pay a bit more. A solid choice for everyday layering or for casual activities.
Most of us here at Kinfield are unapologetically Team Merino when it comes to base layers, and we're not alone. Merino wool is one of the best types of base layer you can buy, for good reason. It is the warmest option, naturally wicking, antimicrobial (no funky odors!), and relatively easy to care for. The only downside here is cost, and the fact that wool can be slightly bulkier than silk, which makes it sometimes harder to layer.
Choose a wool base layer if... you want a versatile, all-around option, and are willing to invest in a layer you'll keep for years. You really can't go wrong with merino layers—just be sure to care for them according to the tag. Many are machine washable these days, but hanging dry will keep them intact for longer.
Bamboo base layers are a fairly new creation, but they're a great alternative for anyone who wants a vegan option, or if your skin might be irritated by wool fibers. Bamboo materials are also anti-microbial and are often even better than wool or silk for wicking, so they're a solid choice for sports, too. The only downside to bamboo layers is that they are not as commonly available, and are still pricier than synthetics.
Choose a bamboo base layer if... you're a vegan, if you're allergic to wool, or if you're looking for a natural fiber option for active sports.
Cotton makes a terrible base layer because it pulls heat away from your skin, and takes forever to dry once you sweat in it. Opt for anything else.
Ready to gear up? Here are some of our team's favorite brands for base layers:
Best for Wool: Smartwool
Our favorite wool layers—their leggings and quarter-zips are universally beloved.
Best For Affordability: 32 Degrees
A super affordable option with most layers under $25, 32 Degrees makes synthetic layers in XS-XL.
Best for Prints: Kari Traa
No one does Scandi-inspired layers like Olympic skiier Kari Traa's eponymous line. They come in a variety of colorful prints and a range of materials.
Best for Inclusive Sizing: REI Co-Op
Great color selection and an inclusive size range (XS to 3X) makes these a great option for both silk and merino.
Best for Sports: Patagonia
Best for Bamboo: Bambool
Bambool uses both bamboo and wool materials, making this a functional go-to for outdoor sports.
Best for Year-Round: Freefly Apparel
Freefly Apparel uses bamboo fibers for a great year-round option in a variety of cuts and colors.
Best for Silks: L.L. Bean
We love their silk layers for both men and women, and their inclusive sizing.
Best for Socks: Darn Tough
They only make socks, but they make socks VERY well. And with their lifetime warranty, buying these is a no-brainer.
See you out there!