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REI Co-op Midweight Half-Zip Review

An excellent value synthetic base layer, perfect for chillier days or to be used by itself as a light mid layer
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REI Co-op Midweight Half-Zip Review (The REI Co-op Midweight Half-Zip didn't at first grab our attention, but we found a high performance base layer, once...)
The REI Co-op Midweight Half-Zip didn't at first grab our attention, but we found a high performance base layer, once we started running our lab tests and taking it out onto the trails.
Credit: Justin Simoni
Price:  $60 List
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Manufacturer:   REI Co-op
By Justin Simoni ⋅ Review Editor  ⋅  Apr 24, 2024
75
OVERALL
SCORE


RANKED
#4 of 16
  • Warmth - 25% 7.0
  • Breathability - 20% 7.0
  • Comfort and Fit - 20% 8.0
  • Durability - 15% 8.0
  • Drying Speed - 10% 7.0
  • Layering Ability - 10% 8.0

Our Verdict

The REI Co-op Midweight Half-Zip is a warm base layer with more durability than wool. The Goldilocks fabric is not too hot, nor too cold, and every other stitch, seam, and design decision is well made. It scores strongly in just about every performance metric we have, providing a ton of value, which remarkably is also extremely competitive for such a quality piece of clothing. When conditions gets chilly but we don't want to grab a wool layer, this is the synthetic we reach for the most.
REASONS TO BUY
More durable than most any wool layer
Surprisingly breathable for the weight
Useful half-zip
Comfy thumb loops
REASONS TO AVOID
Soft fabric may catch on some mid-layers
Synthetic fabric a little heavier than wool of same warmth

Compare to Similar Products

 
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Price $60 List
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$39.95 at REI
Overall Score Sort Icon
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Star Rating
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Bottom Line Reach for this base layer when the temperature drops to wear underneath your jacketA fine Merino base layer at an entry-level pricepointA high-value piece whose breathability and airy fit means that it can be worn for high-output activity regardless of the season, but not your go-to layer for mid-winter warmthThis top is an impressively breathable and lightweight base layer built for activities where you are creating a lot of heatA simple, functional base layer with performance issues consistent with the price point
Rating Categories REI Co-op Midweight... Meriwool Merino 250... Patagonia Capilene... Helly Hansen Lifa S... REI Co-op Lightweig...
Warmth (25%)
7.0
7.0
4.0
5.0
5.0
Breathability (20%)
7.0
8.0
9.0
8.0
8.0
Comfort and Fit (20%)
8.0
8.0
8.0
7.0
7.0
Durability (15%)
8.0
6.0
7.0
9.0
6.0
Drying Speed (10%)
7.0
7.0
10.0
8.0
8.0
Layering Ability (10%)
8.0
7.0
7.0
6.0
6.0
Specs REI Co-op Midweight... Meriwool Merino 250... Patagonia Capilene... Helly Hansen Lifa S... REI Co-op Lightweig...
Measured Weight (Size Large) 10.0 oz 8.6 oz 3.8 oz (size medium) 5.2 oz 7.1 oz
Measured Shirt Length (Size Large) 29 in 30 in 29 in (size medium) 27 in 29 in
Material 92% recycled polyester, 8% spandex RWS Merino wool 2.3 oz 100% recycled polyester double knit 100% Lifa Dry 92% polyester, 8% spandex
Fabric Weight Class Midweight Midweight Ultra Lightweight Lightweight Midweight
Fit Semi-fitted Slim fit Slim fit Slim fit Semi-fitted
Thumb Loops Yes No No No No
Air Dry Test 55 min 65 min 30 min 45 min 45 min
Dryer Safe Yes, tumble dry low No Yes No Yes
Odor Control Fabric None Naturally odor resistant HeiQ® Mint odor control None None
UPF Sun Protection 50 50+ None listed None listed 50+
Seam Stitching Flatlock seams Flatlock seams Flatlock seams Flatlock seams Flatlock seams
Shoulder Top Seams No (rolled forward design) Yes Yes Yes No
Drop Tail Hem No No Yes No Yes
Available Cuts Crew, 1/2 zip Crew, 1/2 zip Crew, short sleeve Crew Crew, short-sleeve, 1/2 zip, tall

Our Analysis and Test Results

We've been pleasantly surprised and more than impressed at just how well REI Co-op has executed its own line of clothing, including the Midweight Half-Zip base layer. The design features a half zip, out-of-the-way thumb holes, and a double-padded collar. It provides a surprising amount of warmth for not being wool, and it dries quickly.

Performance Comparison


rei co-op midweight half-zip - the rei co-op midweight half-zip performs solidly in so many of our...
The REI Co-op Midweight Half-Zip performs solidly in so many of our metrics, it's been hard to find any weaknesses!
Credit: Justin Simoni

Warmth


Cozy! With an advertised fabric weight of 220 grams per square meter, the REI Co-op Midweight Half-Zip will get you better prepared for chillier alpine starts than many other synthetic tops in our roundup. In our testing, we found its performance to be a little less than a wool top of comparable weight, but not by too much. The big advantage you get from this synthetic base layer is much better durability.


You'll find some very welcome features to help thermoregulate, including comfy, well-designed thumb loops to protect and warm your hands. They won't replace gloves but can assist with keeping drafts from creeping up your sleeves. The front zipper travels halfway down the front, allowing you to dump tons of heat out after hard ascents. And when you're ready to zip things back up, the high, double-padded collar will keep your neck warm.

Our exercise test helps us understand the warmth and breathability qualities of each base layer.
Credit: Justin Simoni

Breathability


Surprisingly, we found the breathability of the REI Co-op Midweight Half-Zip much better than we anticipated. The midweight synthetic fabric isn't going to be as breathable as some of the flyweight synthetics in our lineup, but it performed more than adequately in the barrage of tests we threw at it - especially for the weight of the fabric. We found that this fabric absorbed approximately 52% of its weight in water when fully wetted and spun dry, which rates slightly less than the wool/wool blends we tested and on par with other synthetics. This gives support to the theory that wool fabric holds onto water internally a little more easily than synthetics.


Our simple air permeability tests using a peak flow meter also showed favorable results. Generally, in a base layer, you want a fabric that has lofted-up material to both to have nooks and crannies for warmed-up air to occupy while also allowing water vapor to escape to the next layer up. Air passed through the fabric of the Midweight Half-Zip easier than most other synthetics of similar weight, though not as well as the loftiest of wool tops. This continues a trend where this fully synthetic top performs almost as well as a far more delicate and usually more expensive wool upper.

rei co-op midweight half-zip - breathability is quite exemplary for such a heavy base layer, either...
Breathability is quite exemplary for such a heavy base layer, either wearing it alone, or underneath several layers.
Credit: Justin Simoni

Comfort and Fit


We found the REI Co-op Midweight Half-Zip true-to-size, fitting close to our body without being too tight, which works well as a base layer that anticipates having more layers worn on top of it. Smooth, flatlock seams are used throughout the garment, further enhancing the top's comfort rating. The half zip is padded at the collar, so you won't be in contact with the zipper's perchance icy-cold metal.


The fabric does have a little stretch in it, care of the 8% spandex within. Stitching is used quite minimally. Although there is a top seam on the shoulder, it's located a little forward from the center line and shouldn't abrade or annoy one when wearing a backpack. You'll find semi-raglan sleeves on the Midweight Half-Zip which complements the gusseted under-the-arm area to allow a little more room to stretch when raising up your arms in triumph of your latest summited peak.

rei co-op midweight half-zip - flatlock seams are used throughout the rei co-op midweight half-zip...
Flatlock seams are used throughout the REI Co-op Midweight Half-Zip, but thankfully no seam is found at the apex of the shoulder, helping keep rubbing from a shouldered pack at a minimum.
Credit: Justin Simoni

Durability


Durability is certainly one of the many stronger qualities of the REI Co-op Midweight Half-Zip. It's synthetic midweight fabric has proven to us that it can take a beating far better than most any wool or wool blend. Strong flatlock seams are everywhere and allow the fabric to stretch. If you're planning on wearing your base layer as your only layer, this would be a good choice. It's not as durable as some other synthetics we've tested, but it is a whole lot more comfortable due to the fabric's soft hand and the addition of just a touch of the additional stretch from the embedded Spandex.


In our extended real-world tests, we experienced no seams coming undone, no pilling of the fabric, no rips or tears. The fabric also comes back to its original shape after being stretched out. And to add another feather to its impressive cap, the Midweight Half-Zip can be machine washed and tumble dried on low. So go ahead and plan to use it as your go-to baselayer all winter, then stuff it into the deepest bowels of your hiking pack in the summer.

rei co-op midweight half-zip - this is the base layer we'd choose if you're wanting to wear the...
This is the base layer we'd choose if you're wanting to wear the shirt as your top layer through difficult terrain.
Credit: Justin Simoni

Drying Speed


Our line dry test resulted in fair to good results for the REI Co-op Midweight Half-Zip—just about what we expected for a top with heavier fabric, 220 grams per square meter. As mentioned above, approximately five ounces of water—52 % of the total weight of the fabric — was absorbed when we washed and spun dry this garment, which then needs to evaporate off.


This time can be drastically reduced by first wringing out the shirt before putting it out to dry - something you can do without fear of damaging the fabric of this fully-synthetic top. And at home, putting this in the dryer on low still follows the manufacturer's suggestions.

rei co-op midweight half-zip - synthetics are durable enough to use a little body language when...
Synthetics are durable enough to use a little body language when drying, so go ahead and don't be too worried about wringing this layer of water!
Credit: Justin Simoni

Layering Ability


Once again, the REI Co-op Midweight Half-Zip beautifully navigates a narrow channel when it comes to the various characteristics of the chosen fabric. The material is thicker than many other synthetics we've tested but not so thick that we feel it should be a designated mid-layer. The material is also soft, but not so soft that we feel it won't slide over most any other layers you put over it. The inclusion of just enough Spandex into the fabric allows it to move and conform to your own body without feeling too clingy. All in all, we're quite impressed.


Several features of the Midweight Half-Zip do make it stand out when it comes to layering, none of which we enjoyed more than the thumb loops. When utilized, they can help keep the sleeves in place and not lost in several other layers of clothing. The half zip can also help with breathing a little easier by having a way to dump out a little heat when you can't stop to take off a layer until later. Branding is kept to an absolute minimum, which we generally like to champion. Using this base layer as your top layer won't seem out of place even in town, as this top doesn't have an “underwear” feel to it.

The under-the-radar thumb loops which can help keep your hands warm and protected from the elements in lieu of gloves were one of our favorite details of the REI Co-op Midweight Half-Zip.
Credit: Justin Simoni

Should You Buy the REI Co-op Midweight Half-Zip?


It's really hard to come up with reasonsnotto recommend the REI Co-op Midweight Half-Zip - especially for the price - except for those who need the absolute maximum performance that only a wool or wool blend is going to offer. For those seeking out an alternative to wool or who need the durability that a synthetic has in spades over wool, the Midweight Half-Zip turns out to be one of our favorite base layers for colder conditions to recommend.

rei co-op midweight half-zip - we always love discovering great gear that let's us spent more time...
We always love discovering great gear that let's us spent more time in some of our favorite places.
Credit: Justin Simoni

What Other Base Layers Should You Consider?


The Under Armour ColdGear Base 4.0 Crew is fairly similar to the REI Co-op Midweight Half-Zip, though we found it to be a little more durable. It does lack zip and thumb loops and isn't as wallet-friendly. For budget wool, take a look at the Meriwool Merino 250 Long Sleeve, which is similar in price but less durable. If this base layer is too heavy, look at the more svelter Patagonia Capilene Cool Lightweight L/S.

Justin Simoni