The Best Long Underwear and Base Layer for Men Review
There is an overwhelming array of options in the base layer marketplace. It seems as if every company has their own proprietary technology that they proclaim is the best ever created; all the while prices creep upwards. To make sense of this bewildering situation, we took eight of the most popular men's long underwear tops through a battery of tests. They've endured a lot this winter; from the gentle groomers of the bunny slope to literal alpine first ascents on 13,000 ft peaks. Throughout the process we explored the differences between options using a variety of metrics including warmth, breathability, comfort, layering, and durability. We put them through a geeky drying speed experiment and did our best to objectively evaluate their styling.
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Test Results and Ratings
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Analysis and Award Winners
Best Overall Pair of Long Underwear
Smartwool NTS Mid 250 Crew
Best Bang for the Buck
Patagonia Capilene 3 Crew
Top Pick for Versatility
Patagonia Capilene 4 Expedition Weight 1/4 Zip Hoody
Analysis and Test Results
A good layering system is required to be safe and comfortable in the outdoors. The foundation of the modern layering system is next-to-skin long underwear. This appropriately named 'base layer' has arguably the greatest impact on your comfort during active pursuits. It is the only piece that comes in close contact with your skin. Small defects in design, like chafing stitches or an improper fit, can become frustrating agonies during extended use.
Maintain some perspective, however, if a fabric is itchy you will be annoyed, but if it collects moisture and doesn't keep you warm when wet, you could be dead. It is for this reason that cotton has almost disappeared from technical outdoor apparel. But one of the shirts tested is marketed for outdoor winter use, yet still contains 60% of the stuff. We find this irresponsible. From this you should see that the selection of appropriate long underwear is more important than it may initially seem; both for your happiness and health.
To learn more about proper layering systems for outdoor activities, reference our three part layering systems article.
This review examines midweight layers, ideal for the three seasons outside summer. For lighter shirts that will work for running and other warm activities see Best Running Shirt Review. Thicker insulating options are examined in The Best Fleece Jacket for Men Review. See also The Best Women's Long Underwear Review.
Types of Base Layers
Wool vs. Synthetic
The most popular base layers today largely fall into two categories: wool or synthetic. Each offers their own set of advantages and disadvantages. Typically, wool in the premium long underwear marketplace means merino wool, which is made from a special breed of sheep with finer fibers that make it softer than the scratchy sweaters of old. It is warmer for the weight than synthetic, dries quickly, and will not absorb odors. It is, however, expensive, delicate, and an allergy to some.
The synthetic garments currently available are primarily composed of polyester, which is sometimes combined with a secondary material (spandex, elastane, etc.) to add specific design properties, like elasticity or warmth. Synthetics, although cheaper and more durable, offer lower performance in warmth and breathability, and can get stinky after awhile.
The world's most popular fabric, cotton, will not insulate when wet and can actually draw heat away from the body. This is what makes it so nice to wear in hot and humid climates, but also means it is inappropriate for use in the variable conditions found away from central heating. The prices are usually tempting, but taking cotton into an active outdoor setting is ill advised and potentially dangerous.
Thick vs. Thin
Selecting the right base layer is a balancing act because no piece can be all things at once. While testing this gear we came to the conclusion that the best way to predict a top's performance in many of our evaluation criteria was to feel whether it was thick or thin. This is, of course, a relative term: thick or thin compared to what? Well, compared to the other shirts reviewed. Overall we saw the thinner layers doing better in breathability and drying speed while generally costing less. But they predictably did worse in warmth and durability. The reverse was true for thicker tops.
So what does this mean for the discerning shopper? Match your selection to the expected conditions and exertion levels. If you like getting out a lot or doing different things, this may mean multiple purchases. Merino wool companies have made the decision making process easier by standardizing the way they sell their clothing. The descriptions typically include a measure of density for the fabric, usually in g/m˛. This practically translates to thickness. The lightest shirts come in at 100 g/m˛ while the thickest could be as high as 400 g/m˛ (the tops reviewed range from 165 to 250 g/m˛). This allows shoppers to more easily compare across brands or to pieces they already own.
The marketers of synthetics have also tried to do this, although not as precisely. Their tops are usually classified as light, mid, or expedition weight from thinnest to thickest. Comparison, however, is not always well calibrated between brands. Patagonia uses their own system for the Capilene line that ranges from 1 to 4 that can provide some guidance if you have one of their shirts on hand.
Whatever way you choose to measure it, you will still eventually have to decide which thickness you need. We suggest the thinnest tops for the heat of summer and vigorous activities. The usefulness of expedition weight layers may not extend far outside winter or low exertion stuff like ice fishing. For this review we selected mostly midweight shirts that should function in a broader range of situations.
Criteria for Evaluation
We did our best to compare each product using objective and measurable criteria. However, in some areas, like styling and comfort, this can be difficult. When deciding which base layer to get, your personal preferences should be more important than our opinions. Consider your own body type and intended uses as well. For more guidance on how to go about this process, please see our article How To Choose the Best Long Underwear and Base Layer Tops.
Warmth is an important consideration when selecting long underwear, but it should not be the only consideration. After all, if warmth were all that mattered, we would all be sweltering in down, one-piece, jumpsuits. Rather, warmth must be combined with breathability to create an effective layer that can be worn comfortably when active or at rest. Consider these two variables when selecting the best shirt for your intended use. High exertion activities or warmer temperatures may be better enjoyed in a lower warmth scoring product. Just like Goldilocks' porridge, long underwear should not be too hot, or too cold, but just right.
For our purposes, warmth was measured without consideration for weight. Each piece was rated according to the insulation they provide relative to the other products in this review. Generally wool layers were warmer for their weight than the synthetic counterparts. Apart from the 60% cotton Duofold Midweight Crew, all the other shirts will insulate when wet.
Complicating this evaluation criterion are tops with hoods, high collars, and thumb loops. Each of these features increases warmth and versatility, effectively making the garment wearable in a wider range of temps. These features, however, also add weight and bulk, and do affect the styling. They may not be desirable for everyone in a next-to-skin layer or for those with insulating or shell layers that also include these designs. Activities with lots of stop and go energy output, like backpacking or climbing, are ideal uses for tops with more of these temperature regulation options. Many of the crew neck tops tested are also available in versions with some or all of these features. See the 'Other Versions or Accessories' section of each individual review to find out.
Breathability is the yin to warmth's yang. While lying on the couch, who doesn't love warm, cozy clothing? But when on the move, your body starts to warm up, and that heat needs to escape, or you will be trapped in a nightmare of sweat. This is where breathability becomes important. Defined as the ability of a fabric to allow moisture vapor to pass through it; a breathable shirt will allow the moist air produced from perspiration to escape through the material and into the environment without saturating the fabric.
The products we tested would all be considered breathable when compared to the laminated fabrics of waterproof shells, where this property is much more important and variable. If your intended use requires you to frequently wear one of those shells, such as cold weather kayaking or fishing, then the performance of your long underwear in this area is not very significant. Additionally, keep in mind that because these tops are so breathable they will not offer any protection from wind. For blustery conditions they will have to be paired with a hard/softshell or one of the ultra-light, nylon, wind shirts that are beginning to gain popularity.
Among the shirts reviewed, however, there were notable differences. The highest scoring in breathability was the Under Armour Base 2.0, whose thin, checkerboard fabric released moist air better than any others. The merino wool options also performed well and took longer to absorb moisture or feel wet than the synthetics of comparable thickness. On The North Face Expedition Long Sleeve Zip Neck the combination of thick synthetic fabric and tight fit resulted in the worst breathability.
Getting wet in the outdoors is unavoidable. Whether it is from precipitation outside or sweat from within, your long underwear will eventually get wet, and when it does, the time that it takes to dry can have a significant impact on your comfort and warmth. Many of these products advertise proprietary technologies that speed drying, like the waffled Polartec® Power Dry® fabric of the Patagonia Capilene 4 Expedition Weight 1/4 Zip Hoody or the Moisture Transport System on Under Armor's Base 2.0. To cut through the baloney, we conducted an air dry test to measure each shirt's time to dry in a controlled setting.
This experiment was straightforward: we got all the tops completely soaked, hung them up, and watched how long it took them to dry. It was as boring as it sounds. The times we measured were not important in absolute terms. Your shirts will not be drying at the same temperature or humidity and probably will have a warm body to assist the process. Rather, it was the performance of each shirt relative to the others that was significant. For this reason, in our reviews we have changed the time in hours we recorded to a percentage comparable to the best or worse finisher. We think this is more fair and useful. Keep in mind, though, that some of the tight fitting tops, like the Under Armor Base 2.0, might have performed even better with the fabric stretched over a body, creating more space for air to pass between fibers, instead of simply being hung on a hanger.
From that experiment we came to one conclusion that now seems logical and obvious; thin fabrics dry faster than thicker fabrics. The Patagonia Merino 2 Lightweight Henley was the winner in this test and also happened to be the thinnest layer. It dried in less than half the time of the worst performers. Across all of the layers tested, thickness was a better predictor of performance than material or advertised features. This should be an important (and common sense) consideration for retail shoppers and heavy sweaters.
Our air dry test also corroborated merino wool manufacturers' claims that wool can absorb up to 30% of its own weight in moisture before feeling wet to the touch. Before starting the test, each of the shirts had to get soaked. The merino wool layers resisted, and had to be physically agitated underwater before they would become fully saturated.
Besides the Merino 2 Henley's button neck, the rest of the field is crew necks that work best either next to the skin over just a thin t-shirt or tank. The Under Armor Base 2.0 was the exception. Its form fit prevents it from being comfortable on top of anything else. This category did not impact the overall review too much because it is not a true requirement for a base layer. Therefore, it only accounted for 10% of the overall score.
The high cost of some of these pieces makes durability an important consideration. All are quality made and performed well in this category. There were no obvious failures in fabric or stitching. When examined from a long term view, however, it becomes likely that the synthetic options will outlast their wool counterparts. One of the testers liked to joke that merino wool layers make great golf shirts because pretty soon they all have 18 holes. This is certainly an exaggeration, but we did find the fabric more susceptible to scrapes and abrasion. The explanation for this is that the greater warmth of wool for the weight allows it to be sewn into a thinner garment then a comparably warm synthetic; predictably, durability suffers.
The synthetic options all scored well on durability; so you can wash the stench they attract off without fear of wearing through the fabric. This longevity adds to their already superior value. A higher durability rating for some of these tops generally coincided with a greater thickness.
Comfort and Fit
A base layer's comfort and fit should probably be the most important selection factor, but, unfortunately, it is also the most subjective to evaluate. For this review we tried to consult with testers from a range of body types and interests to fairly assess what is often a personal opinion. Small details, like the pattern of stitching or a piece's tendency to hold a static charge, became important considerations. The amount a top rose at the waist with arms overhead, which untucked the shirt and exposed the stomach to cold, was another objective measure we explored.
In the end, most of the tested products performed quite well. They all are sewn with flatlock seams which don't overlap and are far less likely to chafe than the coverstitch of a regular t-shirt. This may not help you differentiate between any of the layers in this review, but it is important to consider should you do some shopping outside our selections. The fabrics used were all soft and cozy, although more of our testers preferred merino wool to synthetics. However, the unique fleece lining of TNF Long Sleeve was the exception and was universally recognized as the comfiest.
Subtle differences in the pattern of the shoulder stitching on the Smartwool NTS Mid 250 Crew made it more comfortable to wear with a pack than the Icebreaker Oasis. This became an important factor in the close competition between these two excellent tops for best overall base layer and illustrates the level of detail we sometimes have to go into to make decisions. The only real loser in the comfort and fit metric was the Base 2.0. Several testers felt it unpleasantly constricted their armpits, causing chafing and irritation.
Best for Specific Applications
Wool Allergy: Anyone who is physically bothered by the itchiness of merino wool should first consider Patagonia's Cap 3 Crew and Cap 4 Hoody.
Team Sports: Traditional sports athletes competing in cold weather will probably appreciate the breathability of Under Armor's form fitting Base 2.0.
Casual around town/aesthetic We think Smartwool's NTS Mid 250 Crew is the most stylish of all the tops and makes the best gift for the fashion conscious because it lacks the company logo on the left sleeve that the Icebreaker Oasis has.
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— Jack Cramer
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