Apr 7, 2022 9:00 AM

The Best Winter Base Layer Tops and Bottoms for Outdoor Fun

A merino wool, synthetic, or blended base layer top and bottom are your secret to dressing right for the outdoors.

If you buy something using links in our stories, we may earn a commission. This helps support our journalism. Learn more. Please also consider subscribing to WIRED

Featured in this article

Black long sleeve shirt hanging on an outdoor clothesline shoulders pinched by clothespins

4 / 9

Dressing yourself for the outdoors starts with layering. Rather than scrounge for just one ultra-thick parka or pair of winter pants, start with a solid top and bottoms. Base layers—clothing that fits right against your skin—are the foundation of building a flexible clothing system for outdoor adventures and for a simple boost of warmth underneath your regular street clothes.

From the choice in fabrics to the location of the seams, a lot of engineering goes into a base layer that sets it apart from a common cotton undershirt. It has to be comfortable and non-chafing, and it needs to wick away sweat to the outer clothing layers so you won't stay damp. There are a lot of undershirts and base layers. Few are terrible, but few really stand out. These are our favorites.

Be sure to check out our guides to the Best Hiking Gear, Best Climbing Gear, Best Multi-Tools, Best Tents, Best Sleeping Bags, Best Sleeping Pads, Best Camping Cookware, Best Portable Grills, Best Binoculars, Best Merino Wool Clothes, Best Rain Jackets, and How to Re-Waterproof Your Rainwear.

Updated March 2024: We've removed several tops that have since been discontinued, as well as reoriented our guide toward long-sleeve tops of various fabric weights for more options. We've also added matching bottom layers.

Special offer for Gear readers: Get WIRED for just $5 ($25 off). This includes unlimited access to WIRED.com, full Gear coverage, and subscriber-only newsletters. Subscriptions help fund the work we do every day.

If you buy something using links in our stories, we may earn a commission. This helps support our journalism. Learn more. Please also consider subscribing to WIRED

Best Synthetic Top
Patagonia Capilene Cool Daily Shirt
While merino wool may get accolades for its softness next to the skin, the Patagonia Capilene's 100-percent recycled polyester fabric feels downright luxuriously silky. The Capilene Cool Daily is snug but not at all restricting, no matter how awkwardly I'm craning myself on a rock wall to grab the next handhold or ducking underneath a log that's fallen across the hiking path. And at such a low price, you can afford to buy several and rotate through them so you always have a fresh one.
$55 at Patagonia (Women's Sizing)
$55 at Patagonia (Men's Sizing)
$55 at Backcountry (Women's Sizing)
$55 at Backcountry (Men's Sizing)
Photograph: Scott Gilbertson
Best Wool Top
Smartwool Merino Classic Long Sleeve
I like this base layer from Smartwool a lot. Polyester outdoor wear is getting to be pretty soft these days, but a 100-percent merino wool layer like this still has a certain unique, pillowy softness. This shirt is an ideal weight, and the tight weave kept me warm but not too warm. The seams lie flat and sit off the shoulder to prevent abrasion underneath backpack straps, as any half-decent base layer should.
$90 at REI (Men's)
$90 at REI (Women's)

Best Synthetic Bottoms
Patagonia Capilene Midweight Bottoms
Like the Capilene Cool Daily shirt, these polyester bottoms wicked away sweat faster than any pure merino wool layer and stretched enough not to inhibit my mobility. Being a midweight fabric, these are a little thicker than the lightweight shirt we recommend. Bonus points to Patagonia for using 100 percent recycled material in its fabric.
$79 at Patagonia (Women's Sizing)
$79 at Patagonia (Men's Sizing)
$79 at Backcountry (Women's Sizing)
$79 at Backcountry (Men's Sizing)
Best Wool Bottoms
Smartwool Classic Thermal Merino Bottoms
Smartwool nails the fit in a non-restrictive form that hugged my skin without hugging it to death. These were warm and snug, yet they didn't restrict my movement at all. The waistband lay flat and didn't give me any problems digging into my hips, and they seemed to offer just a bit more room than the all-merino Ibex bottoms.
$81 at Backcountry (Women's Sizing)
$81 at Backcountry (Men's Sizing)
$115 at Smartwool (Women's Sizing)
$115 at Smartwool (Men's Sizing)

Best Blended Bottoms
Ibex Woolies Pro Tech Bottoms
I've yet to test a synthetic-wool blended top since the excellent Patagonia Capilene Air Hoodie was discontinued, but these 85-percent merino/15-percent polyester bottoms from Ibex fit the bill quite nicely. Blends augment merino's warmth-while-wet capabilities with polyster's propensity to dry out more quickly. These had a nice amount of stretch in them and didn't restrict my movements, no matter how high I lifted my legs. Just size up, because they run small.
$115 at Ibex (Women's Sizing)
$115 at Ibex (Men's Sizing)
Photograph: Ibex
If You Want a Hood
Ibex Indie Hoodie
Hooded base layers—also known as sun hoodies—are still a bit of a rarity among 100-percent merino wool tops, but they come in handy for protecting yourself from the sun's rays. Because it has no elastane blended into the fabric, the fit on this one isn't as snug as most of the other base layers in this guide. It is fully featured, though, with thumb loops, a quarter-zip for venting, and lay-flat seams situated away from the contact points of backpack straps and hip belts. At 185 grams per square meter, the Indie is lightweight enough to keep you from sweating too much, as long as you pace yourself.
$170 at Ibex (Men's)
$170 at Ibex (Women's)

Photograph: Icebreaker
Honorable Mentions
Other Base Layers
The following are a few others we like, though not enough to give them a slot above:
Ibex Woolies 2 Crew for $125 (Women's Sizing, Men's Sizing): Of the three all-merino-wool top layers I tested, this one had the loosest fit. Base layers should be snug to fit underneath other layers and to wick away sweat. I liked that the seams were off the shoulders, and it felt like a substantial garment.
Icebreaker Merino 260 Tech Crewe for $125 (Women's Sizing, Men's Sizing): This is a fantastic 100-percent merino base layer. It almost hurts to stick it in the honorable mentions section. It just fits slightly looser than the Smartwool that snagged the top spot. However, there are no seams on top of the shoulder, so if you plan to backpack, you may want to pick this one instead.
Ibex Woolies 2 Bottoms for $135 (Women's Sizing, Men's Sizing): I really enjoyed wearing these. The material was warm, thick (but not too thick), and gloriously soft. So why did the Smartwool Classic Bottoms edge them out? The fit was just the slightest bit better on the Smartwools, as the Ibex were a bit restrictive in the crotch. Yet, the Woolies 2 have a stellar rolled-top waistband that resists digging into your gut. Seriously, why don't all tights have these?
Icebreaker Merino 260 Tech Thermal Leggings for $125 (Women's Sizing, Men's Sizing): There's nothing to complain about with these, only that the slightest of differences gave the nod to the competing Smartwool and Ibex bottoms in the 100-percent merino space. They fit snugly but not too snugly, they didn't restrict my movement, and the fabric is ultra comfy. It just lacks the slightly better fit of the Smartwool and the slick rolled waistband of the Ibex.
Uniqlo Heattech Crew Neck Long Sleeve T-Shirt for $20 (Women's Sizing, Men's Sizing): This long-sleeve base layer blend of polyester, acrylic, rayon, and spandex isn't exactly an outdoor-specific garment, as the seams are in the wrong places for an outdoor base layer and there are no bonus features, such as thumb-loops. But for a casual day hike or car-camping trip, these sticking points don't matter as much.
Helly Hansen Lifa Merino Seamless Top for $110 (Women's Sizing, Men's Sizing): Senior associate editor Adrienne So says it's incredibly stretchy and light, and it's thin enough to fit under the snuggest mid-layer. It uses a unique two-layer construction where the outer layer is 100 percent merino wool and the interior is synthetic. Ventilated mesh panels on the body and under the arms help with overheating, though it may feel chilly if you're wearing it during low-intensity activities.
Ridge Merino Aspect Midweight for $75 (Women's Sizing, Men's Sizing): The Aspect is made of merino wool spun around a nylon core (84 percent merino, 16 percent nylon). It has offset shoulder seams, flat seams under the arms, and thumb holes that are hidden under a triangular piece of cloth in each sleeve cuff. Senior associate editor Adrienne So says a versatile layer that could nicely handle the transition from walking around in 30-degree-Fahrenheit temperatures to a hot and crowded house party.
Tracksmith Harrier Long Sleeve Top for $84 (Women's Sizing, Men's Sizing): Another blend of merino wool and synthetic, the Harrier is a basic base layer without fancy details or offset stitching. It's senior associate editor Adrienne So's go-to for outdoor runs. The fabric hangs perfectly without clinging or riding up, and it dries within a few hours.
Keep Your Money
Avoid These Base Layers
Not every base layer is worth your hard-earned dough. These are the ones I tested and found weren't quite up to snuff.
Ibex Woolies Pro Tech Crew for $115 (Women's Sizing, Men's Sizing): This one lost points for its extremely snug fit. I'd say size up, but then the sleeves will be too long. Thumb holes in the cuffs are appreciated, and the material (85 percent merino/15 percent nylon) was silky soft. The seams are mostly off the shoulder, preventing backpack strap abrasion, but not entirely.
Smartwool Intraknit Thermal Merino Crew for $130 (Women's Sizing, Men's Sizing): The Intraknit fit extremely snugly, although you could size up without the sleeves being as abnormally long. The seams lie almost right on top of the shoulder, so I'd be concerned about backpack straps rubbing, and the fabric—nearly half polyester/half merino wool—wasn't as soft as the competition.
Smartwool Intraknit Thermal Merino Bottoms for $104 (Women's Sizing, Men's Sizing): Don't be fooled by the name. These are roughly half polyester and half merino wool. These were thicker and warmer than the blended Ibex bottoms I recommend, but they restricted my movement whenever I tried to step up onto or over a high obstacle. Like any merino/synthetic-blended garment I've tried, they tend to run a size small.

Base Layer Basics
As the layer immediately in contact with your skin, you'll always be wearing a base layer. It's the foundational step in the entire outdoor layering system. Beyond just adding warmth, it wicks away sweat by transferring it from your skin to outer layers, where it can evaporate without making you cold or irritating your skin. Base layers also provide abrasion protection from outer layers, which may not be as soft, and backpack straps. Lucky for you, we put together this guide on How to Layer Outdoor Clothing.

Matt Jancer is a former staff writer for WIRED who focused on reviewing outdoor gear. Previously, he spent a decade as a freelance writer covering automobiles, motorcycles, and lifestyle stories for magazines. Some of his longest gigs were at Car and Driver, Outside, Esquire, Playboy, and Popular Mechanics.

Former Writer and Reviewer

Topicsbuying guides Shopping camping Winter Gear outdoor wool

The Best Headphones for Working Out

Rock your inner jock with a pair of sturdy, sweatproof, and tangle-proof headphones. Here are our favorites.

Adrienne So

The Best Corkscrews for Every Kind of Wine

From kitchen basics to a $400 sommelier status symbol, a wine writer tested 30 corkscrews and these are his favorites.

Jordan Michelman

Breathe Easy—We Found the Best Air Purifiers

Keep wildfire smoke, smog, and allergens out. We tested standard and HEPA models to find the right one for your home.

Lisa Wood Shapiro

Missed Out on Prime Day? These 155 Deals Are Still Going Strong

You can still snag many of the same Prime Day deals on security cameras, hair straighteners, and iPads—though these discounts are quickly disappearing.

Julian Chokkattu

The 34 Best Prime Day Deals Under $100

A selection of our favorite cheap-ish Prime Day Deals from security cameras to water filters.

Martin Cizmar

The 270 Best Prime Day Deals, Tested and Tracked By Our Team

From laptops, tablets, phones, and smartwatches to Amazon Echo Dots, these are the best Prime Day deals on all your favorite WIRED gear.

Scott Gilbertson

The Best Travel Strollers for Your Summer Adventures

Whether you’re on a road trip or a plane ride, these are our favorite travel strollers that fold as flat as possible.

Nena Farrell

Tesla’s Cheaper Long-Range Model 3 Is Back

Plus: The Ford Capri returns as an EV, Samsung workers are on indefinite labor strike, and the market for anti-obesity drugs is messier than ever.