Last updated January, 2018: We’ve added new picks for 2018. Prices and links have also been updated.

Base layers need to do three things in order to perform well in the outdoors. They need to keep you warm through insulation, they need to breathe well during aerobic activities, and they need to wick moisture away from your body and allow it to evaporate. While your good ol’ waffle-style long johns might be comfortable and cozy near the fire, they no longer cut the mustard when it comes to modern needs. Merino wool, synthetic materials and a host of alternatives are better designed to accomplish all three objectives well, and they can be relied upon to do the job when you need them most.

Contributions by Tanner Bowden and AJ Powell.

Merino Wool

Natural Fibers that Shake the Scratchy Wool Stigma


Merino wool is the gold standard in base-layer materials. Its fibers are naturally antimicrobial, so they fight the stench that occurs after a few days on the trail, and the fabric is great at regulating temperature, making it usable in multiple environments. It also breathes well and wicks moisture away from your body to keep you dry.

From left to right (lightweight to heavyweight)
Merino 150 Base Layer Short Sleeve by Smartwool $75
Merino 150 Base Layer Bottom by Smartwool $75
Bergtagen Woolmesh Sweater by Fjällräven $160
Bergtagen Longjohns by Fjällräven $140
Tech Top Long Sleeve Half Zip by Icebreaker $120
Tech Leggings by Icebreaker $110

Synthetics

High Performance at an Affordable Price Point


Synthetic materials pack a big punch at a low price point. While they tend to pick up a stench easier than other materials, they do the trick of keeping you warm and wicking moisture away quickly. They’re also highly breathable, and after purchasing, they leave a little bit of extra guap in your wallet for something like a nice pair of hiking boots or new goggles.

From left to right (lightweight to heavyweight)
Capilene Lightweight Crew by Patagonia $49
Capilene Lightweight Bottoms by Patagonia $49
Expedition Long Sleeve Zip Neck by The North Face $80
Expedition Tights by The North Face $80
UA Base 4.0 Crew by Under Armour $85
UA Base 4.0 by Under Armour $85

Alternatives

From Yak Wool to Bamboo


Recently, many manufacturers have started making base layers out of alternative materials. The below examples include bamboo wovens, yak wool and silk. They offer similar performance to merino and synthetic materials, but also offer other benefits, such as sustainability (as with bamboo fiber).

From left to right
Featuring yak wool:
Nomad Crew LS by Peak to Plateau $103
Concordia Leggings by Peak to Plateau $96
Featuring bamboo:
Hemisphere Merino LS by Tasc Performance $110
Elevation II Base Layer Pant by Tasc Performance $120
Featuring silk:
Silk Underwear Crewneck by L.L.Bean $48
Silk Underwear Pants by L.L.Bean $48

One Piece Suits

Channel Your Inner Ninja


Onesies are a great way to keep warm on super-cold days. Even if the material is a lighter weight than you would typically wear on a cold day, the one-piece construction retains heat better than a top/bottom combo, so it’ll keep you plenty warm. As a bonus, they make great Halloween costumes.

From left to right (coolest to warmest)
Merino Ninja Suit by Airblaster $200
Supermons 3/4 One Piece by Mons Royale $200
Super One-Piece by Norrona $219