What thermal underwear to choose for the military in winter?

The cold season is the most challenging for the military. Lowered temperatures, high humidity levels, prolonged periods of immobility, or conversely, high physical exertion, all have a negative impact on the body. Therefore, properly selected military thermal underwear is not just about comfort, but also about maintaining the combat effectiveness and lives of the soldiers. In this material, we will break down what thermal underwear is, how it works, why not all of it is warm, and which materials are best to choose.

Why is not all thermal underwear warm?

Thermal underwear is functional and technological clothing designed not to provide heat, but to regulate heat exchange and wick moisture away from the body. Many people mistakenly believe that such underwear automatically warms you up. In reality, its effectiveness depends directly on the conditions of use.

What functions thermal underwear performs:

• wicking moisture away from the skin;
• maintaining dryness levels;
• forming an insulating layer;
• maintaining stable body temperature, etc.

At the same time, by no means all thermal underwear for the military is warm. The range includes thin models designed for active movement rather than for reducing the impact of frost. Some models may feature the wrong material, such as natural cotton, which causes them to accumulate moisture and increase the level of cold.

In cases where thermal underwear is worn without a second layer of clothing, it also leads to hypothermia. The same applies to selecting underwear without considering weather conditions.

Why should there be better thermal underwear for the military?

Thermal underwear for the military should be chosen with significantly higher requirements in mind than when dealing with similar technological clothing for civilians.

This is due to the following factors:

• prolonged exposure to the cold without the possibility of changing clothes;
• alternating periods of activity and statics;
• limited access to drying facilities for clothing;
• increased physical exertion;
• risk of hypothermia and frostbite.

Therefore, high-quality thermal underwear for the military should be selected considering its ability to quickly wick away moisture, which guarantees an increase in warmth. Such thermal underwear should maintain a comfortable temperature even with increased humidity and not chafe under gear and equipment. Models for the military are more comfortable, featuring flat seams to avoid skin irritation, and possess a higher level of wear resistance.

If an inferior model of men's military thermal underwear is chosen, it will quickly deteriorate in field conditions and stop performing its functions.

Experience from the front: what the winter of 2025–2026 showed

The winter of 2025-2026 confirmed the importance of such an element of clothing as military thermal underwear. This season served as a reminder that "thermal" is not just another layer of clothing, but a means of preserving a soldier's health and forming protection against hypothermia.

Note the recommendations of specialists based on the findings of the winter season:

1. Have a spare set of thermal underwear: one set should be on you, the other, dry, in your backpack. This will help you get rid of a wet set by changing into dry clothes. After all, in wet clothing, it is impossible to get warm even near a stove or burner, especially during evacuation or guard duty.
2. Test the thermal underwear before heading out: you should test military thermal underwear to avoid overheating under armor. To do this, put everything on—from the base layer to the jacket—and then move around, engage in usual activities to assess the level of comfort.
3. Pay attention to layering: it is important to consider the number of layers of thermal underwear. Also, do not wear cotton models, as they absorb moisture and increase the greenhouse effect, reducing comfort levels.

Remember that even high-quality thermal underwear will not work correctly without following the rules of layering. It is important that military thermals are made of synthetic materials. They are not only more wear-resistant but also more functional and significantly warmer than cotton.

Soldiers who took new thermal underwear for the winter noted that its thickness should also be considered. A base layer that is too thick causes discomfort during active movement. As a result, one may face overheating and increased sweating, leading to a greater sensation of cold.

How to choose high-quality thermal underwear

Thermal underwear for a soldier is chosen according to several main criteria that will help not only increase comfort but also guarantee its effectiveness.

When selecting thermal underwear, pay attention to:

1. Size: thermal underwear should fit snugly to the body, so pay attention to the manufacturer's size chart to be able to choose clothing that fits your parameters.
2. Weather conditions: one layer of underwear may be sufficient for wicking sweat in the summer season, especially during prolonged exertion and physical activity. This will help avoid overheating and increase comfort. In winter, when the outdoor temperature drops sharply, several layers of underwear should be combined for both thermoregulation and insulation.
3. Materials: cotton thermal underwear is in low demand because it tends to absorb moisture and increase the level of cold as a result. Synthetic fibers are the optimal solution for this type of clothing. They are not prone to deformation, maintain optimal temperature, and are wear-resistant. Premium-level underwear for professional military personnel often contains polyester, elastane, and fleece, thanks to which it wicks moisture, retains heat, and has antibacterial properties.
4. Quality: military clothing must be of optimal quality. The underwear should be made of high-quality fabrics and have no visual defects that could impair the experience outdoors in warm or cold weather.

Also note that thermal underwear for the military can have different levels of material density. Most often, winter models made of fleece have a higher density, providing better warming properties.

It is necessary to consider not only the material but also the type of fabric and the percentage of fibers in it. For comfort, one should also pay attention to the presence of zonal ventilation, which helps prevent the body from overheating and wicks away moisture.

The anatomical cut and snug fit of fleece thermal underwear to the body will guarantee increased comfort, an absence of chafing, and will not affect the speed of movement.

Which thermal underwear materials actually work?

Thermal underwear for a soldier can consist of various materials, which depend on its type, functionality, and purpose.

Materials differ depending on the levels of underwear:

• first (base): the main task of this level is wicking moisture and preventing cooling. Therefore, such underwear should be exclusively synthetic, consisting of polyester, polyamide, and more modern fabrics like Termoline, Coolmax, and others;
• second (insulation): the underwear in this layer is responsible for heat retention, especially during low activity and cold outdoor temperatures. Proven solutions include fleece, viscose fibers, rip-stop, Polarheat, and other materials.

Fleece thermal underwear is in steady demand in winter conditions. It provides rapid moisture wicking, dries quickly, has a high level of durability, and is also capable of warming even when wet.

Polypropylene underwear is often seen—a material that does not absorb moisture, making it ideal for the first layer of clothing. Combined fabrics also deserve attention, especially if they contain synthetic and partially natural fibers.

Which level of thermal underwear to choose?

Thermal underwear can have different levels, according to which it should be selected, emphasizing the specifics of use as well as the level of exertion.

Pay attention to the following nuances:

1. High physical activity: during training, assaults, and more, you should choose so-called level one underwear. It will help take care of moisture wicking and eliminate the greenhouse effect and overheating.
2. Lack of physical activity: while sitting in a trench or bunker, during observation, or sniping, it is worth choosing the second or third level of underwear. It has more insulation and retains heat even in extreme weather conditions.

Level one underwear is basic, designed for those who move actively. Level two has more insulation and is suitable for moderately cold climatic conditions. There is also a level three of underwear, designed for low temperatures and a lack of physical activity over a long period.

Military personnel can combine the first and second levels of thermal underwear, as this helps ensure a high level of effectiveness and prevents rapid freezing in difficult weather conditions.

Mistakes military personnel make when choosing thermal underwear

Thermal underwear is just as important an element of equipment as protection, a first-aid kit, and others. Therefore, care should be taken to avoid popular mistakes that can lead to freezing or overheating.

Typical mistakes include the following:

1. Buying cotton models: natural fibers are a must-have for civilian life and skin care. In the case of thermal underwear, natural fabrics guarantee increased sweating, faster wetting, and hypothermia.
2. Combining thermals with regular clothing: wearing a tank top or T-shirt under thermal underwear is a poor decision, as the skin will not be able to wick away moisture.
3. Incorrectly chosen size: the underwear should not compress the skin or, conversely, hang loosely on it, which leads to discomfort or health issues.
4. Choosing the wrong level of underwear: one should not confuse level one and level two thermals, as this can lead to hypothermia or overheating of the body.
5. Washing with regular detergent: in this case, the clothing will lose its properties because detergent particles will clog the fibers.

These mistakes can lead to reduced comfort levels as well as active hypothermia even in relatively mild frost.

Thermal underwear for a soldier is a key element of equipment that not only warms but also provides moisture control, stable body temperature, and comfort during active movements.

Your level of efficiency in various weather conditions will depend on the correct choice of underwear, so special attention should be paid to materials, levels, conditions of use, and other nuances to provide yourself with high-quality clothing.