By now you’ve probably refreshed your wardrobe already with some new base layer winter shirts. But in case you haven’t had the chance yet, it’s not too late to grab a couple since winter is not yet over and you’re likely to use this kind of garment almost everyday. You also won’t just be using these shirts during winter but probably well into the start of spring since they are also designed to be comfortable even with jackets off.

What is a base layer shirt?

A base layer shirt is basically any kind of shirt that serves as the first layer of clothing underneath thicker garments such as winter sweaters or jackets. A good thermal shirt should be able to do the following:

• Retain warmth when needed - This is an absolute must which is why regular long sleeved shirts just won’t do. A proper base layer shirt should be made of materials that trap heat in when needed but not be uncomfortably warm once you remove your jacket indoors. 
• Absorb sweat - Base layer shirts are typically made of synthetic fabric or wool since these can effectively “wick” sweat without feeling clammy against your skin. Some fabrics also feel light even after absorbing sweat and even allow faster evaporation of moisture.  
• Antibacterial - Since thermal base shirts are designed to be activewear, most will be made of fabrics with antibacterial properties to prevent body odor even after absorbing sweat. 
• Be comfortable - As mentioned above, base layer clothing often uses a special kind of fabric that is able to wick sweat, keeping your skin dry while retaining heat. These fabrics will also be comfortable and will not irritate or chaff skin even if constantly rubbing against it. Base layer shirts are also cut and tailored to be fitted, even skin tight, but comfortable.

Fabrics used for base layer thermal shirts 

You should carefully consider the type of fabric used when buying a thermal base layer shirt. Each has its own advantages and disadvantages, but for most shoppers, the bottomline is the “snug factor” or how comfortable they are with the material. These materials also come in different thickness and your choice will depend on how cold it is indoors and outdoors in your area. Here are some choices for base layer winter clothing material that you may come across: 

• Synthetic fabrics - Nylon, polyester, and other kinds of hybrid synthetic fabrics are probably the most popular since they are cheap but offer decent absorption, insulation, and comfort. 
• Wool - Natural wool, particularly Merino wool, is found in higher-end base layer shirts since it is naturally antibacterial, very comfortable, and regulates temperature more effectively. 
• Smart fabrics - These are often hybrid fabrics, sometimes a combination of Merino wool and synthetics, that have been engineered to provide the most desirable qualities in a base layer winter shirt.
• Cotton - Although not typically preferred, there are some brands that still use cotton, mostly blended with other fabrics since cotton is comfortable and cheap.
• Exotic fibers - You may also come across exotic fibers like silk and even bamboo being used in a base layer thermal shirt. Silk is light and particularly comfortable especially for activewear while bamboo is said to be friendly to sensitive skin while having great moisture wicking and antibacterial properties.

Top base layer winter wear of 2021

Without any further adieu, here are some of our top picks for base layer clothing for men for this year. 

Carhartt Men's Base Force Midweight Classic Crew

• Uses waffle-knit, odor-fighting polyester 
• Wicks away sweat faster, allows easier movement (FastDry and Rugged Flex technologies)

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ViCherub Men's Thermal Underwear Set Long Johns with Fleece Lined Base Layer Thermals Sets for Men

• Polyester and spandex lined with fleece 
• Anti-static
• 4-way stretch fabric

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Under Armour Men's HeatGear Armour Compression Long Sleeve T-Shirt

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Smartwool Merino 150 Baselayer Pattern Long Sleeve

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Patagonia Capilene Cool Lightweight Long-Sleeve Shirt

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Lululemon Keep the Heat Thermal Long-Sleeve Shirt

• Breathable wool fabric (SenseKnit)
• Ribbed with supports for training
• Temperature regulating

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NIKE Men's Pro Warm Long Sleeve Top

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As you may notice, Merino wool base layer shirts are still the most expensive, and for a good reason - they are the most comfortable and great at regulating temperature. However, you may want to go with synthetic fiber for training purposes as they are lighter, dry faster, and designed with strategic supports that allow better flexibility. This said, it's better to buy one shirt for training, another one for casual outdoor, and another one for indoors when shopping for base layer winter wear.