10 Best Mens Thermal Underwear 2026 in the United States

The WEERTI Thermal Underwear for Men is a solid choice if you're looking for reliable warmth during cold weather. It features a soft fleece lining made mainly of polyester and a small amount of spandex, which makes the fabric stretchy and comfortable without feeling tight or restrictive. This four-way stretch fabric allows for easy movement whether you're layering it under clothes or wearing it at home. The material's weight strikes a nice balance—not too bulky but still warm enough to lock in your body heat throughout the day. A big plus is the moisture-wicking ability, which helps pull sweat away from your skin and controls odor, keeping you dry and fresh even during active use. This makes it versatile for wearing at the gym, outdoors, or just lounging around.

While polyester is great for warmth and moisture control, it might not be as breathable as natural fibers like wool, so if you’re extremely active or prone to overheating, you might want to consider that. Also, since the product is machine washable, care is simple, which is always convenient. The fit is described as flexible and non-bunching, meaning it should feel comfortable under your clothes without riding up or feeling bulky. This thermal set works well as a base layer for anyone needing dependable warmth in cold conditions, whether for outdoor activities or everyday use. If softness, stretch, and moisture control are important to you, WEERTI’s thermal underwear covers those bases nicely.

The Fruit of The Loom Men's Recycled Premium Waffle Thermal Underwear Long Johns are designed to keep you warm in cooler weather, making them a solid choice for anyone looking for reliable thermal wear. The use of U.S. sourced cotton and recycled polyester not only provides comfort but also supports eco-friendliness. The soft mini waffle fabric is gentle on the skin, adding to the comfort factor, while the moisture-wicking feature helps keep you dry by pulling sweat away from your body. This is particularly beneficial for activities like hiking or spending time outdoors in winter.

In terms of construction, the reinforced flat seam design minimizes chafing and adds durability, which is an advantage for long-term wear. The pull-on closure type makes them easy to wear, and they are machine washable, adding to the convenience factor.

While the fabric is designed to be warm, it offers less insulation compared to thicker thermal options available on the market. The fit may vary depending on personal body shape and size, so trying them on or checking sizing charts is crucial. Although these long johns are made from recycled materials, they might not appeal to those looking for completely natural fibers.

The Under Armour Men's ColdGear Armour Fitted Mock is designed to keep you warm and dry in cold conditions, making it a solid choice for anyone needing reliable thermal underwear. Its dual-layer fabric has a soft, brushed interior for warmth and a smooth exterior that dries quickly, which is great for managing sweat during active use. The fitted design is streamlined—not too tight or loose—offering comfort without restricting movement.

Stretch-mesh panels under the arms and on the back add ventilation in key areas to prevent overheating, which helps maintain comfort during physical activity. The 4-way stretch construction allows freedom of movement in all directions, so you won't feel restricted. The mock neck adds extra coverage and warmth around the neck area, useful on chilly days. At about 1.4 pounds, it’s lightweight enough to wear under other layers without feeling bulky.

This model offers a good balance of warmth, comfort, and moisture-wicking for cold-weather activities, excelling in thermal insulation and fit.