The REI Co-op Midweight delivers solid value for those seeking an affordable, all-purpose synthetic base layer. It’s soft, stretchy, and more comfortable than many techy synthetics, with enough warmth for most winter activities and durability that far outpaces merino at this price. Breathability and odor resistance fall short of higher-end options, making it less than ideal for high-output pursuits. But for $55, it’s a reliable, versatile piece that punches above its weight in comfort and quality.
Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
Fabric(s)
92% polyester, 8% spandex
Fabric weight
220 g/m²
Weight
9.7 oz.
Variations
Half-zip
Pros
Cons
REI Co-op Midweight
For this season's top models, see our guide to the Best Base Layers.
With a 220-grams-per-square-meter (g/m²) polyester build, the REI Co-op Midweight sits squarely in the midweight category. On paper, it appears warmer than a base layer like the Arc’teryx Rho (190 g/m²), but in practice, it offered about as much insulation as the REI Co-op Merino 185, if not a little less. On a test day in the mid-20s with steady snow, it provided a solid foundation but didn’t stand out as particularly warm, and it certainly lacks that instant-insulation feel you get with merino. I wore it under a midweight waffle-knit quarter zip, a Patagonia Nano Puff, and the Patagonia Powder Town ski jacket, and the system kept me comfortable without overheating.
Synthetic fabrics like the REI Co-op Midweight’s polyester generally excel at breathability, but this piece isn’t the best option if airflow is your top priority. Its relatively thick fabric insulates more than ideal for high-output activities and dries slowly once saturated with sweat. Compared to high-performance synthetics like The North Face Summit Series Pro 120 or Patagonia Capilene Thermal Weight, which use lighter fabrics and raised grid patterns for ventilation, the Midweight feels basic. Even the merino-blend Smartwool Intraknit Thermal adds strategic mesh vents for better heat management. All told, the Midweight is serviceable for moderate activity but far from our first choice for breathability-focused performance.
The REI Co-op Midweight feels impressively durable and well-made for its price point. The 92% recycled polyester and 8% spandex blend has a substantial feel, and after multiple washes (air-dried afterward), it shows no signs of pilling or wear. It does lack the harder face of synthetics like the Arc’teryx Rho LT and The North Face Summit Series Pro 120, which I’d be far more likely to wear as standalone pieces while hiking or even climbing. But compared to merino base layers of a similar weight, the Midweight is far more resistant to tearing and abrasion. For $55, the durability-to-price ratio is excellent.
When I first tried on the REI Co-op Midweight, I was pleasantly surprised by how soft and comfortable it felt. Unlike many synthetics—such as The North Face's Summit Series Pro 120 or Outdoor Research's Echo—that have a plasticky, tech-forward feel, the Midweight feels more natural, somewhere between cotton and merino wool. I wouldn’t hesitate to wear it under a sweater to work—that’s how non-techy and wearable it feels.
The fabric’s 8% spandex adds plenty of stretch, making it easy to move in without restriction. The regular fit further boosts all-day comfort—close enough for layering but never tight. Thoughtful details like thumbholes (perfect for hiking without gloves), offset shoulder seams, and a well-placed neckline seal the deal. Unlike some base layers that creep too high under the chin or dip awkwardly in the back, the Midweight’s neckline hits just right.
Odor resistance has never been a strength of synthetic base layers, and the REI Co-op Midweight is no exception. While many modern synthetics use antimicrobial treatments to combat lingering odors, the Midweight sticks to a simple 92% polyester and 8% spandex build with no added protection. After just a few uses, it develops that classic “base layer smell” that washing only partially removes. At $55, it’s hard to fault it too much, but if odor control is essential, opt for merino or a treated synthetic alternative.
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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.
Recycled Materials
Recycled materials are prevalent in outdoor gear, with nylon, polyester, wool, and down among the most common, but the composition varies widely. A green check mark indicates the product is made with a substantial amount of recycled materials (100% recycled or the core fabric that makes up most of the product is recycled), a yellow check means it contains a moderate to small amount of recycled materials, while a red X means there are no recycled materials in the product.
Bluesign Approved
Bluesign Technologies, based in Switzerland, operates a third-party textile management system that ensures materials are manufactured to strict environmental, chemical, and worker safety standards. A green check mark indicates a product is either a Bluesign Product (contains at least 90% Bluesign-approved fabrics and 20-30% Bluesign-approved accessories) or features a significant amount of Bluesign-approved materials. A yellow check mark means it uses some Bluesign-approved materials but less than the aforementioned category, and a red X means there are no Bluesign-approved materials in the product.
Responsible Manufacturing
This criterion evaluates a brand’s commitment to fair wages, safe working conditions, and reducing environmental impact through certifications and programs like Fair Trade Certified, Fair Wear Foundation, Worldwide Responsible Accredited Production (WRAP), and the Fair Labor Association, while also recognizing brands that manufacture primarily in the U.S. or Europe under strict labor and environmental regulations. A green check mark indicates a brand meets our responsible manufacturing criteria, while a red X means it does not.
Recycled and/or Reduced Packaging
Packaging can add significant waste to outdoor gear purchases, so many brands work to reduce its impact by using recycled materials, incorporating Forest Stewardship Council-certified paper products, and minimizing plastic and paper use. A green check mark indicates a brand uses recycled or reduced materials across all of its packaging, a yellow check indicates moderate or limited use of recycled or reduced packaging, and a red X indicates the brand does not make either of these efforts.
Resale and/or Recycling Services
Resale and recycling programs help keep outdoor gear in circulation longer and out of landfills, ranging from trade-in resale platforms that offer store credit to take-back initiatives that recycle products at the end of their usable life. A green check mark indicates a brand offers both resale and recycling programs, a yellow check mark indicates it offers one or the two, and a red X indicates it offers neither.
Carbon Footprint Tracking
This criterion evaluates whether a brand measures, reports, and works to reduce its greenhouse gas emissions using established frameworks such as the Higg Index, Greenhouse Gas Protocol, or The Change Climate Project. A green check mark indicates a brand publicly reports greenhouse gas emissions data, sets clearly defined reduction targets, and uses established tracking frameworks such as Higg or The Change Climate Project. A yellow check mark indicates the brand tracks emissions and outlines reduction goals but provides limited data, lacks science-based verification, or does not clearly report progress. A red X indicates the brand does not appear to track greenhouse gas emissions or provides so little information that its efforts cannot be verified.
Annual Impact Report
Annual impact reports provide transparency and accountability by outlining a brand’s sustainability efforts across areas such as material sourcing, greenhouse gas emissions, waste, water use, supply chains, and packaging. A green check mark indicates a brand publishes a detailed, brand-specific impact report that closely aligns with our sustainability criteria and leaves little room for ambiguity. A yellow check indicates a brand provides some relevant sustainability reporting but lacks detail in key areas or is covered only briefly within a parent company report. A red X indicates a brand does not regularly publish an impact report.
Tester: 5’4” 145 lb.; 36" chest; 30” waist
Size tested: Women’s medium
I usually wear a small for a snug fit and a medium for something more relaxed, and since I hadn’t tried REI tops before, I wasn’t sure what to expect. The medium ran true to size with a regular fit—not skin-tight but not overly loose either. Personally, I prefer a little extra room, so I was happy with the choice. The length is good for layering, and I appreciated the thumbholes, which keep the arms in place when I pull on my midlayer.
Helly Hansen Lifa Stripe ($45): An Iconic Budget Base Layer
The Helly Hansen Lifa Stripe is an iconic polypropylene base layer that has been a staple in the ski world for decades. It lacks the clean and classy vibes of the REI Midweight (the striped arms won’t pass in casual settings), and the polypropylene material feels more techy than the Midweight’s soft polyester. But it’ll save you $10 and definitely fits the part at the ski resort. To learn more, check out our Lifa Stripe review.
REI Co-op Merino 185 ($80): REI’s Midweight Merino
Merino offers several clear advantages over synthetics, including excellent warmth-to-weight performance and outstanding odor resistance, making it a favorite for multi-day use. Affordable merino is rare, and at $80, the REI Merino 185 is a decent deal. Compared to the REI Midweight synthetic, it delivers slightly more warmth in a lighter, thinner package. The trade-off? Durability takes a hit, and our tester found it noticeably scratchier than premium merino options. And neither are great choices for sweat-inducing activities. If you're looking for budget-friendly merino, we’d still recommend the Ridge Merino Aspect Midweight for its softer feel and added nylon for durability. For more, read our review of the Merino 185.
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.
Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
The Lifa Stripe is an iconic layer from Helly Hansen for just $50. It’s all function here: The polypro material feels somewhat plasticky and isn’t particularly cozy, but it moves sweat away from the skin and dries quickly. Unfortunately, the fit isn’t refined, and there’s no odor-resistant technology.
Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
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.
Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
The REI Co-op Midweight is a smart choice for budget-conscious adventurers who want dependable warmth and synthetic durability at an approachable price. It strikes a comfortable middle ground—soft, stretchy, and comfortably suited for casual winter activities and layering under casual attire.
Go for it if you value affordability and need a no-frills base layer for skiing, hiking, or daily layering.
Skip it if you prioritize high-output breathability or advanced odor control—you’d likely be better off with merino or more technical synthetic alternatives.
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