Smartwool Merino 250 1/4 Zip - Women's Review
Compare prices at 3 resellers Pros: Wide range of thermoregulation, cozy materials, no odor after long wear, longer fit through torso and arms, versatile
Cons: Stretches after wearing for several days, thick construction isn't ideal for warmer days
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Our Analysis and Test Results
This top performer continues to prove itself in all conditions. The Smartwool Midweight 1/4 Zip is the one you want if warmth and comfort are your top priority; a heavier construction with the softest materials, warmest performance, and excellent thermoregulation. This is the layer to wear under a fleece and jacket in super cold weather or on its own when you start to shed your layers.
This top is warm and offers excellent thermoregulation. If you're seeking a base layer that will keep you warm when the temperatures plummet, this is our top recommendation. While it's advertised as a midweight construction, it's thicker than any other midweight contender, loaded with a fabric weight of 250 g/m² of merino wool, making it exceptionally warm. We tested it across a wide range of temperatures, ranging from 0 to 75 degrees Fahrenheit.
During an exceptionally cold week in Colorado, we had the opportunity to test the warmth of this high performer. The thicker construction, when pulled on, immediately begins to insulate. The fine fibers hold heat but also release moisture. With its 100% merino wool construction, the material is porous enough to allow moisture to escape when moving, which ultimately keeps you warmer.
The length is ample through the arms, and torso length is ample and with a lot of stretch. When wearing it under a down vest, we were easily able to pull the arm cuffs over our hands when clouds came in to compensate for our lack of gloves. It offers full coverage with a thicker construction, making it an excellent cold-weather addition to your outdoor wardrobe. It is ideal on most ski, hiking, bike missions in the winter, and works well on its own or under a light layer in shoulder seasons. Due to its warmth, do not expect to wear this top much in the summer months.
Merino wool is known for its excellent breathability. The 100% merino construction of this top has a looser weave than other merino tops, making it surprisingly breathable right through the face fabric. The ¼ zip allows you to vent easily, making it more versatile than most crew base layer tops on the market. While this is a breathable base layer, it's far from our first choice for aerobic or sweaty sports during warm months because of its thicker construction. For this use, we'd opt for a thinner build.
During our testing, we took this top on many missions, from climbing to running. While running, we learned this top is best for colder days of the season. Depending on how warm you run, this may be best for winter, or it may work for you in the shoulder seasons. We prefer to use it for cold early morning runs.
During warm weather, we found ourselves keeping it on before really building up a sweat and having to strip it off. When wearing a backpack, we found the material retained and held sweat where breathability was poor with our outer layers. However, these wet spots still stayed warm, even when we cooled down. The materials also dry very quickly. Overall, this is a breathable but thick layer, doing best in cold or cool weather in a layered system. On its own, it'll do well for any mission through the year.
Comfort and Fit
This base layer is comfortable with an attractive fit for our testers, and we believe it will work well for most wearers. It features 100% merino wool fabrics that feel luxuriously soft on the skin with flat seams. Next to skin, the materials are soft and plush, not even a little bit itchy. Unfortunately, it does stretch, and after wearing it for multiple days on end, this fabric doesn't bounce back until it's been washed and dried.
We wore this top while climbing, hiking, and running through Colorado, Arizona, and Nevada. During our rigorous testing period, we wore it for four days straight (without washing!). The fit of this top is fitted with nice coverage throughout. The length is long through the torso and arms for ladies of any size. The collar is roomy as well. During these four days, the top never started to smell, even after 10-mile runs in the mountains. It did, however, start to stretch out a little bit after day two.
While this never changed the long-term fit of the top, it's a point of consideration. This was never an issue with the previous iteration that seemed to have a slightly thinner and lighter construction. That said, when throwing it into the washer and dryer, it came back to its shape and size. Overall, we love, love, love the comfort and coziness of this fabric. The trade-off is a little stretch when wearing it extensively for multiple days in a row.
The slim construction offers decent layering ability. The ¼ zipper design will layer a tank top or shirt underneath, much easier than any crew top. It doesn't ride up, stays in place, and ultimately layers well in any outdoor outfit.
To layer jackets or fleeces over top of this base layer, you need to do a bit of work, especially if your fleece is tight. This is because the face fabrics are fuzzy and have a little more friction than tops that integrate synthetics or polyester.
Under a looser fleece or jacket, though, it does just fine. Add it to your winter collection and layer it as apart of your winter adventure wear with ease. Just know that you have to hold the cuffs of the shirt to prevent the arms from bunching up while layering. It doesn't ride up and stays in place while you move all day long.
So far, so good. The 100% merino wool construction doesn't have any seams or material defects after our testing period thus far.
The latest iteration of this top is a little thicker than previous versions, which we imagine might be more durable than the previous version (which feels a little thinner). That said, we owned the previous version and used it regularly for two years and didn't experience any issues. Since this top is very similar, made from the same company and materials, we expect the same performance in this regard. That said, given the merino wool construction, we would recommend avoiding using it for highly abrasive activities. In general, merino wool is a little less durable than synthetic constructions and need to be handle with care. However, this tried and tested piece is one that's surprisingly durable for its material construction.
If comfort and quality are your top priorities, you'll see the value in this base layer top. There's very few that match it across the metrics. That said, the price is steep for some unless you find a great deal online. A good tip is to look for last seasons' model (which also rocks) and find deals on past colors. There are some tops with similar performance at a lower price, but none that are 100% merino wool with the same longevity and overall level of awesome. So, if you can afford it, we'd argue that the value is high.
The Smartwool 250 ¼ Zip is a midweight 100% wool base layer with an exceptional level of comfort and performance. This top performer is a favorite and has been over the last few years we've tested it. This iteration is a little thicker than any other option in our testing fleet, making it an ideal option for colder weather. Wear it as apart of a cold-weather layered outfit or on its own in warm weather. A great fit with plenty of stretch and comfort to last you through the coldest days of winter.
— Amber King
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