Updated on December 31, 2020

A wool base layer is a key piece of gear for many outdoor adventures, as it wicks away moisture to keep you dry, warm, and comfortable even in adverse conditions. Merino is the wool of choice for base layers, since it is superfine and soft without being itchy like traditional wool, and it absorbs sweat without starting to smell. If you’re overwhelmed by your base layer options, don’t worry! We’ll help you choose the best wool base layers for your next hike or backpacking trip.

For more of our top hiking apparel recommendations, check out the Best Base Layers


Quick Answer - The Best Wool Base Layers

  1. Smartwool Merino 250
  2. Icebreaker 200 Oasis
  3. Kari Traa Tikse
  4. REI Co-op Merino
  5. Ridge Merino Inversion


Comparison Table - Best Wool Base Layer

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Smartwool Merino 250Midweight50+$$$4.8Read Review
Icebreaker 200 OasisLightweight20$$$4.7Read Review
Kari Traa TikseLightweightNone$4.6Read Review
REI Co-op MerinoMidweightNone$4.3Read Review
Ridge Merino InversionHeavyweight50+$$4.9Read Review
Want to learn more about a technical term? Check out our Features Explained section below.

Need buying advice? Take a look at these Things to Consider.

Reviews - The Best Wool Base Layers for Hiking

Smartwool Merino 250

View Women's Version
  • Weight: Midweight
  • UPF: 50+
  • Paneled Construction Provides a Comfortable & Flattering Fit
  • Flatlock Stitching on the Seams Prevents Scratching
  • Sun Protection with a UPF 50+ Rating


The Smartwool Merino 250 is an excellent base layer choice for wearing underneath other layers on cold adventures or simply wearing on its own around town or for a quick trail run on cooler days. Constructed from panels with flatlock stitching, the long-sleeve crewneck features a flattering fit with seams that stay out of the way under the straps of a pack.

If you’re wearing this base layer on its own, the UPF 50+ sun protection will prevent damage from UV rays. This base layer can be machine washed without worry about shrinking, yet it also can be worn on long adventures without starting to stink.

Icebreaker 200 Oasis

View Women's Version
  • Weight: Lightweight
  • UPF: 20
  • Underarm Gussets Enhance Mobility
  • Offset Shoulder Seams Keep from Rubbing Under a Pack
  • Droptail Hem Offers Additional Coverage


The Icebreaker Oasis 200 is a lightweight base layer that is made to handle all the variations in weather conditions you can find in the outdoors. It’ll be your go-to warm layer from early spring to late fall, and will even keep you warm in cooler winter conditions. Plus, it also offers some UPF protection for those sunny days as well. This top is easy and comfortable to move in, thanks to underarm gusseting, and the offset seams at the shoulders won’t get irritated under a heavy pack.

Despite its droptail hem, the Icebreaker 200 Oasis tends to run short through the torso and arms, so it might not be the best choice for taller people.

Kari Traa Tikse

  • Weight: Lightweight
  • UPF: None
  • 4-Way Stretch for Full Mobility
  • Slim Fit is Flattering and Layers Well
  • Mesh Panels Provide Ventilation


Kari Traa is a signature European brand that makes base layers for adventurous, outdoorsy women, and its Tikse wool base layer is an excellent women’s option for both style and comfort. The Tikse features 4-way stretch, providing full range of movement without restriction, so you’ll hardly notice you’re wearing this base layer.

Mesh panels provide ventilation where you need it to complement the moisture-wicking capabilities of the merino wool. The strategically placed seams and the slim fit contribute to making the Tikse very flattering if you want to wear it on its own, and it comes in fun colors, too.

REI Co-op Merino

View Women's Version
  • Weight: Midweight
  • UPF: None
  • Droptail Hem Fits Well Under the Hip Belt of a Pack
  • Flat Seams Won’t Scratch or Chafe
  • Body-Hugging Fit Helps Wick Moisture Efficiently


The REI Co-op Merino is a midweight base layer that performs well without breaking the bank. It’s designed to fit fairly snugly, in order to effectively wick away sweat and moisture, yet the gusseted underarm construction doesn’t restrict movement. This base layer features flat seams to avoid chafing and scratching, and the merino wool fabric is soft and not itchy. The drop tail hem is designed to fit comfortably under the hip belt of your pack.

The REI Co-op Merino is not the most durable wool base layer, but the price point is good, and as long as you wear it under other outer layers, it should still hold up for many adventures.

Ridge Merino Inversion

View Women's Version
  • Weight: Heavyweight
  • UPF: 50+
  • Longer Cut to Stay Tucked in When Layering
  • Thumbholes Keep Sleeves in Place
  • Raglan Seam Construction is Comfortable Under a Pack


When your alpine adventures bring you outdoors in wintery conditions, the Ridge Merino Inversion is an ideal heavyweight wool base layer to keep you cozy in the cold. The longer cut is designed to provide extra coverage and stay tucked in under outer layers, and the raglan construction with flat seams is extremely comfortable under a pack, since the seams stay out of the way of the shoulder straps so they don’t rub on your skin. The Inversion also has thumb holes to keep your wrists warm and the sleeves in place.

Ridge Merino is a small business that sustainably sources its materials, so you can feel good about where the wool that keeps you warm comes from.




Wool base layers are almost exclusively made of merino wool, which is much softer than traditional wool, and not itchy at all. It also wicks moisture away from your skin, and because it retains a small amount of that moisture in its fibers, it can actually cool you down when you get warm. Merino wool is also extremely resistant to odor, so you can wear it for days on end if you’re backpacking or on a long adventure.

REI has a great guide on how to choose a base layer, as well as when to wear your base layers.


Wool base layers range from lightweight to mid-weight to heavyweight, and what you need depends on what activities you plan to do the most – and what climate those take place in. Midweight is the most versatile, since it can stand on its own even in somewhat chilly conditions, yet can also be paired with heavier outer layers for colder excursions. Heavyweight is what you want if you spend a lot of time in the alpine, and lightweight base layers are a good choice if you don’t do a lot of winter sports.



As with any article of clothing, fit is important for comfort, but with wool base layers, it is also important for performance. To take advantage of the moisture-wicking capabilities of wool, the base layer needs to be snug-fitting and lay close to your skin. Of course, you still want full range of movement when you’re exploring outside, so look for incorporated stretch and gusseted seams that won’t restrict motion.



If you’re planning to wear your wool base layer on its own, sun protection is a nice feature to protect your skin. Some base layers are rated as high as UPF 50+, while others have no sun protection. If you’re always going to be wearing your wool base layer under outer layers, then the lack of sun protection won’t be as big of a factor for you.

For more information, check out our guide on how to wash merino wool





Seams created without overlapping the fabric, so they are less bulky and not prone to scratch or chafe.


A triangular piece of fabric is sewn into the underarm to provide more mobility and less stress on the seams.


Sewn holes in the sleeves for your thumbs which provide additional wrist coverage and keep the sleeves from shifting or rolling up under other layers.


Waist hem where the back is longer than the front.