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REI Co-op Merino 185 Base Layer Review

Ashley McNeish (ski gear tester)
ByAshley McNeish
Aug 27, 2025
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Our Take:
4/5
Certified

The REI Co-op Merino 185 offers an affordable entry point into 100% merino base layers, delivering solid warmth, moisture regulation, and standout odor resistance for multi-day use. It’s not as soft or durable as premium options from Ortovox or Icebreaker, and it runs hot for high-output activities, but for resort skiing, casual winter hikes, and backcountry trips where laundry isn’t an option, it’s a dependable choice. At $80, it undercuts much of the competition while still offering the core benefits that make merino worth considering.

Warmth

Warmth

3.5/5
Breathability

Breathability

3/5
Durability

Durability

2/5
Comfort

Comfort

3.5/5
Odor Resistance

Odor Resistance

5/5
Sustainability

Sustainability

5/5

Fabric(s)

100% merino wool

Fabric weight

185 g/m²

Weight

8.2 oz.

Variations

Half-zip

Pros

An affordable merino base layer.
The 185-gram weight bridges Smartwool’s two standard offerings (150 and 250g).
Pure merino for those who prefer to wear all-natural materials.

Cons

A bit scratchier than premium merino alternatives.
Despite the flat seams and merrow stitch construction, the lines of stitching can result in pressure points and chafing.
No added durability or breathability features.

For this season's top models, see our guide to the Best Base Layers.

With its 185 grams per square meter (g/m²) fabric and 100% merino construction, the REI Co-op Merino 185 offers midweight warmth for cool to cold conditions. Despite its thin profile, it insulates well, especially once your body generates heat. It feels a touch warmer than midweight synthetics like the Patagonia Capilene Midweight (147 g/m²) and comparable to other merino layers in the same weight class, such as the Ortovox Rock’N’Wool.


Personally, I think 185 g/m² is the sweet spot for merino: warm enough for winter conditions without feeling stifling. On a test day with temps in the mid-20s and a mix of sun and snow, I paired the REI Co-op Merino 185 with a midweight waffle-knit quarter zip, a Patagonia Nano Puff, and the REI First Chair Jacket. The system kept me warm and comfortable without overheating, and the Merino 185 served as a solid foundation for layering flexibility. All told, it’s an ideal base layer for resort skiing and casual cold-weather use, and a smart addition to a summer backpacking kit for evening warmth in camp.

Merino isn’t our top choice for a base layer in sweat-heavy activities—especially in its pure 100% form. It regulates temperature well, wicks moisture from the skin, and stays warm when damp, but it dries slowly and tends to trap more heat than most synthetics. Because of this, the REI Co-op Merino 185 isn’t ideal for high-output pursuits such as skate skiing, extended skin-track climbs, or winter running. That said, it’s perfectly serviceable for resort skiing, casual winter hikes, or snowshoeing, where comfort and consistent warmth matter more than rapid moisture transfer.

The REI Co-op Merino 185 faces two key durability challenges. First, REI’s in-house apparel prioritizes value, and the overall material quality feels a step below premium merino offerings from brands like Ortovox, Icebreaker, and Smartwool. The fabric itself isn’t as fine and has a slightly scratchier feel, which often correlates with lower fiber quality. Second, at 185 g/m², this is about as thin as we’d want to see in a 100% merino piece; thinner merino is typically blended with nylon or polyester to boost abrasion resistance, as seen in a piece like the Black Diamond Solution 150.


As a result of these two challenges, the REI Co-op Merino 185 requires gentle treatment—laundering with care and wearing it under other layers to minimize wear and tear. If you plan to use it as a standalone piece, expect it to thin or develop holes quickly.

Merino is naturally cozy thanks to its warmth and soft hand feel, but the REI Co-op Merino 185 falls short compared to premium options. The fabric feels noticeably scratchier, and my go-to softness test—holding it to my face—confirmed it’s not particularly smooth, which impacts next-to-skin comfort over a full day. On the plus side, the slight added stretch makes it easier to pull on and off and allows for good freedom of movement.


The Merino 185 is certainly not as cozy as other 100% merino base layers like the Icebreaker Merino 200 Oasis or Ortovox 185 Rock’N’Wool, and it falls short even of a synthetic like the Arc’teryx Rho with its brushed-fleece lining and stretchy seams. But if the Merino 185’s other strengths appeal to you, I’d say its comfort is more neutral than a dealbreaker.

Odor control is one of merino’s greatest strengths, and the REI Co-op Merino 185 doesn’t disappoint. The difference compared to synthetic base layers is dramatic—where synthetics can pick up stink within an hour and often retain it even after washing, merino stays fresh for days. This makes the Merino 185 a fantastic option for travel, multi-day backcountry trips, or anyone who can’t wash gear regularly. And because it’s made from 100% merino—not blended with synthetics like the Smartwool Intraknit Thermal or Black Diamond Solution 150—it earns top marks for odor resistance.

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Longevity

Choosing durable outdoor gear and keeping it in use for longer is one of the best ways to reduce environmental impact. Our proprietary longevity rating assesses factors like overall build quality, materials, fabric denier, component durability, and real-world performance. A green check indicates that we expect the product to be long-lasting relative to its peers, a yellow check mark indicates average longevity, and a red X indicates a product that may have a limited lifespan.

Tester: 5’4” 145 lb.; 36" chest; 30” waist

Size tested: Women’s medium

I typically choose a small for a snug fit and a medium for a more relaxed feel, and the medium here worked perfectly. The REI Co-op Merino 185 fit true to size—comfortable without being too tight—with a regular, easy-to-layer cut and a long enough hem that I could tuck it into my ski pants without worrying about it riding up. I appreciated the thoughtful seam placement along the top of the arm rather than the inside, which reduces chafing and adds comfort. While some men report that the men’s version has an overly large head opening (and product photos seem to confirm this), I had no complaints with the women’s design.

Ridge Merino Aspect Midweight ($80): A Better Base Layer, for Less
The Ridge Merino Aspect outperforms the REI Co-op Merino 185 in nearly every category. For the same price, it’s softer, more durable thanks to its 16% nylon blend, and comes in more options—including the women’s Ridge Merino Aspect High Neck and the men’s Aspect Balaclava Hood. Build quality is excellent, with clean stitching and well-executed thumb loops. If you’re set on a 100% merino layer, the REI is tough to beat in terms of price, but the Aspect delivers the same natural benefits of wool with extra durability and comfort-enhancing features. For a deeper dive, read our Ridge Merino Aspect review.

REI Co-op Midweight ($55): More Durability for Less
If you’re here for a good deal, the REI Co-op Midweight deserves a look. This polyester layer delivers similar warmth to the Merino 185, but in a more durable and low-maintenance package. It’s a no-frills option: no venting, a fairly rough hand feel, and virtually no odor resistance. Still, it wicks moisture reasonably well and provides a functional barrier between your skin and a waterproof shell. At $55, it’s hard to complain—just don’t expect premium comfort or long-term freshness. For more, read our REI Co-op Midweight review.

REI Co-op Merino 185 ($80)
Woman packing car in REI Co-op Merino 185 LS Base Layer Top
4/5

The Merino 185 is REI’s 100% merino base layer. The 185-gram weight is a nice middle ground between light and heavyweight alternatives. However, it’s not as soft as we’d prefer and won’t hold up to heavy use as well as merino-nylon blends.

Fabric(s)
100% merino wool
Fabric weight
185 g/m²
Weight
8.2 oz.
Variations
Half-zip
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Warmth

3.5/5
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Breathability

3/5
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Durability

2/5
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Comfort

3.5/5
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Odor Resistance

5/5
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Sustainability

5/5
Ridge Merino Aspect ($80)
Layering over Ridge Merino Aspect Midweight Merino Wool Base Layer LS
4.7/5

The Aspect is a high-quality merino base layer that’s more affordable than much of the competition. Well-designed thumb loops and a drop hem contribute to a classy vibe, and the addition of nylon helps with durability, structure, and dry time. However, inventory can be spotty.

Fabric(s)
84% merino, 16% nylon
Fabric weight
180 g/m²
Weight
8.3 oz.
Variations
Quarter zip, turtleneck (w), hoody (m)
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Warmth

3.5/5
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Breathability

3/5
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Durability

3.5/5
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Comfort

4.5/5
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Odor Resistance

4.5/5
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Sustainability

2/5
REI Co-op Midweight ($55)
Wrist of REI Co-op Midweight LS Base Layer
4.4/5

The Co-op’s Midweight is an affordable, no-frills base layer that’s built to last. But while it gets the job done for casual users, it’s not a standout for comfort, breathability, or warmth.

Fabric(s)
92% polyester, 8% spandex
Fabric weight
220 g/m²
Weight
9.7 oz.
Variations
Half-zip
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Warmth

3/5
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Breathability

3.5/5
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Durability

3.5/5
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Comfort

4/5
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Odor Resistance

3/5
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Sustainability

5/5

Is the Merino 185 for You?

The REI Co-op Merino 185 is best for budget-conscious buyers who want the core benefits of merino—warmth, moisture regulation, and multi-day freshness—without paying a premium. It’s a great match for resort skiing, casual winter hikes, and anyone who values odor resistance for extended trips.


Go for it if you want an affordable, all-merino base layer for low- to moderate-output activities in cool to cold conditions.


Pass on it if softness, durability, or breathability for high-output use are top priorities—you’ll be happier with a premium merino option or a synthetic alternative.

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