10 Best Under Armour Thermal Underwear 2026 in the United States

The Under Armour Men's Armour HeatGear Compression Shorts are designed to be a lightweight and snug base layer, ideal for exercise and fitness activities where you want to stay dry and comfortable. Made from a blend of 84% polyester and 16% elastane, the HeatGear fabric is light and stretches moderately to provide a tight, second-skin fit that supports muscles during movement. It’s great at wicking sweat away from the skin and dries quickly, helping you stay fresh even during intense workouts. The shorts include strategic mesh panels that improve ventilation, which is a nice touch for keeping cool.

Durability is enhanced by the ergonomic seam placement that avoids high abrasion spots, plus the updated gusset adds comfort and support. While the fabric offers some odor resistance, this product does not specifically emphasize anti-odor technology, so you might want to wash it regularly after use. The compression fit is quite tight, which some may find very supportive, but others might prefer a less restrictive option. The wide elastic waistband ensures the shorts stay in place without digging in, and a drop-in strength pocket is useful for small essentials. At just 0.15 pounds, these shorts are very light, making them easy to wear under other layers.

These compression shorts perform well as thermal underwear for active men looking for moisture management, a snug fit, and durability, especially in warmer seasons like spring.

The Under Armour Men's HeatGear Armour Leggings are designed as a lightweight, compression-fit base layer ideal for sports and exercise, especially in milder to cool weather. Made from a stretchy mix of polyester and elastane, they feel snug like a second skin, which helps with muscle support during active use. The material is super light and breathable, thanks to strategic mesh panels that improve ventilation, helping to keep sweat away from the body and dry quickly. This moisture-wicking feature is great if you tend to get hot and sweaty during workouts.

The leggings also include a wide elastic waistband for comfort and a small pocket for storing essentials, which adds convenience. They are built to last with an ergonomic seam design that reduces wear in high-friction areas, enhancing durability. However, because they fit very tightly, they might feel restrictive if you're not used to compression gear, and they do not have a fly, which some may find less convenient. While the product details don’t explicitly mention odor resistance, Under Armour’s fabric technology generally includes this feature, making these leggings suitable for extended wear during intense activities.

Weighing just around 0.12 kg, they won’t add bulk under your clothes. If you’re looking for a reliable, lightweight thermal underwear layer that wicks moisture well and offers strong support for active sports, these leggings are a solid choice. Those who prefer looser or casual thermal wear might find the fit too tight.

The Under Armour Men's Packaged Base 4.0 Leggings are designed to keep you very warm in cold conditions, making them a strong choice if you need reliable thermal underwear. They use a soft, brushed grid on the inside to trap heat and manage your body temperature, which helps keep you comfortable even when it’s very chilly. The material is mostly polyester with a bit of elastane, giving it medium weight and some stretch for decent movement, though it’s not highly stretchable.

The fit is snug and true to size, which is typical for base layers meant to go under other clothes. While they do wick moisture well and dry quickly, which is great for staying dry during activity, these leggings don’t have built-in odor resistance or pockets. The elastic waistband is comfortable and the fabric can handle regular machine washing, so durability is good for everyday use in sports or outdoor activities.

Because these leggings are medium weight, they might feel a bit thick for mild weather but are excellent for fall or colder seasons. If you want a warm, fitted base layer that moves with you and dries fast but don’t need extra features like pockets or odor control, this Under Armour option is worth considering.