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10 Best Thermal Underwear 2025 in the United States

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Our Top Picks

#1

Winner

Cuddl Duds Thermal Underwear for Women - Women's Cold Weather Clothes Fleece Lined Thermal Long Johns Set - Winter Base Layer Clothing Thermal Shirt Top and Leggings Pants 2Pc Set for Women - Black XL

Rating
10.0
Chosen by1,323
Material
Weight
Fit

Most important from
3308 reviews

Material
Soft fabric that invites wearing all day, making it ideal for lounging, outdoor activities, or layering under work attire.
Weight
Exceptionally warm and cozy, perfect for enduring brutal winter conditions without feeling bulky.
Fit
Comfortable stretch allows easy movement while keeping snug, with thoughtful details like thumbhole sleeves that add practicality.
Durability
Maintains shape and fit even after frequent washing, resisting stretching and pilling over time.

The Cuddl Duds Thermal Underwear set for women is designed to keep you warm in cold weather with a cozy brushed fleece lining and a soft matte exterior. Made from a blend of 93% polyester and 7% spandex, it offers a nice balance of warmth and stretch, making the fit comfortable and flexible for everyday activities. This two-piece set features moisture-wicking fabric that helps keep sweat away, which is great if you tend to get warm during physical activities or layering. The fabric is also tightly knit, providing protection from UV rays, a nice bonus if you spend time outdoors.

The thumbhole sleeves and modern rise leggings add to the practical and comfortable fit without adding bulk, allowing you to wear the set both as a base layer or on its own when lounging. At just under 15 ounces, it's lightweight enough for layering without feeling heavy. This thermal set is a suitable choice if you want a soft, stretchy, and warm outfit that works well for casual cold-weather wear, though for intense winter sports or heavy-duty use, you might want to look for additional durability features.

Rating
10.0
Chosen by1,323
Material
Weight
Fit

Most important from
3308 reviews

Material
Soft fabric that invites wearing all day, making it ideal for lounging, outdoor activities, or layering under work attire.
Weight
Exceptionally warm and cozy, perfect for enduring brutal winter conditions without feeling bulky.
Fit
Comfortable stretch allows easy movement while keeping snug, with thoughtful details like thumbhole sleeves that add practicality.
Durability
Maintains shape and fit even after frequent washing, resisting stretching and pilling over time.
#2

Cuddl Duds Thermal Underwear for Women - Women's Cold Weather Clothes Fleece Lined Thermal Long Johns Set Winter Base Layer Clothing Thermal Shirt Top and Leggings Pants 2Pc Set for Women Navy Blue XL

Rating
10.0
Material
Fit
Moisture-Wicking

Most important from
3308 reviews

Material
The fleece lining delivers excellent warmth without adding bulk, making layering effortless and cozy.
Fit
The fit strikes a perfect balance—snug enough to retain heat but not overly tight or restrictive.
Moisture-Wicking
This thermal set breathes well and stays in place during active outdoor use, providing warmth comparable to silk.
Durability
The material resists pilling and fuzzing, maintaining a smooth, high-quality appearance over time.

The Cuddl Duds Thermal Underwear set for women is designed to keep you warm and comfortable during cold weather. Made from a soft, heavyweight blend of polyester and spandex, it provides a cozy fleece lining inside with a smooth, stretchy exterior that moves with you. The spandex stretch ensures a snug but flexible fit, making it easy to wear under clothes or on its own.

It features moisture-wicking fabric that helps pull sweat away from your skin to keep you dry, which is great for active days. The thermal set also offers protection from UV rays, which is a nice bonus if you’re outside for long periods. The comfortable design includes thoughtful touches like thumbholes and a tag-free label to reduce irritation.

While the material blend supports some odor resistance and durability, it's mainly polyester-based, so it may not be as long-lasting as natural fibers like wool. The set is lightweight enough to avoid bulk while still providing good insulation. This thermal underwear is best suited for women looking for a versatile, warm base layer that balances comfort, stretch, and moisture management for everyday cold weather use.

Rating
10.0
Material
Fit
Moisture-Wicking

Most important from
3308 reviews

Material
The fleece lining delivers excellent warmth without adding bulk, making layering effortless and cozy.
Fit
The fit strikes a perfect balance—snug enough to retain heat but not overly tight or restrictive.
Moisture-Wicking
This thermal set breathes well and stays in place during active outdoor use, providing warmth comparable to silk.
Durability
The material resists pilling and fuzzing, maintaining a smooth, high-quality appearance over time.
#3

Merino.tech Merino Wool Base Layer Mens Set - Heavyweight, Midweight, Lite Merino Wool Thermal Underwear For Men Top, Bottom (Large, 250 Charcoal Grey)

Rating
8.8
Material
Fit
Moisture-Wicking

Most important from
2196 reviews

Material
The comfort level surpasses traditional base layers, thanks to the exceptionally soft Merino wool fabric.
Fit
The tailored design ensures a snug yet non-restrictive fit, allowing for a full range of motion during various activities.
Moisture-Wicking
Moisture management is outstanding, with Merino wool wicking away sweat and moisture, keeping you dry and comfortable.
Durability
The durability of the fabric stands out, maintaining shape and performance even after repeated wear and wash cycles.

The Merino.tech Merino Wool Base Layer Mens Set stands out with its use of 100% superfine merino wool, known for being soft and itch-free, ensuring all-day comfort. This set includes both a top and bottom in midweight (250 g/m²), making it versatile for varying temperatures. Additionally, the package includes a bonus pair of merino wool hiking socks, adding extra value.

The natural moisture-wicking and odor-resistant properties of merino wool make this thermal underwear an excellent choice for staying dry and fresh during active use. Its breathability helps regulate body temperature, providing comfort throughout the year. Despite being machine washable, hand washing and air drying is recommended for extended longevity, which might be inconvenient for some users.

The fit is designed to prevent rubbing, overheating, or bunching, contributing to comfort. This set would be particularly beneficial for men needing reliable and comfortable base layers for outdoor activities or everyday wear in cooler climates.

Rating
8.8
Material
Fit
Moisture-Wicking

Most important from
2196 reviews

Material
The comfort level surpasses traditional base layers, thanks to the exceptionally soft Merino wool fabric.
Fit
The tailored design ensures a snug yet non-restrictive fit, allowing for a full range of motion during various activities.
Moisture-Wicking
Moisture management is outstanding, with Merino wool wicking away sweat and moisture, keeping you dry and comfortable.
Durability
The durability of the fabric stands out, maintaining shape and performance even after repeated wear and wash cycles.

Buying Guide for the Best Thermal Underwear

Choosing the right thermal underwear is essential for staying warm and comfortable in cold weather. Thermal underwear, also known as base layers, is designed to provide insulation and wick moisture away from your skin. When selecting thermal underwear, consider the material, weight, fit, and additional features to ensure you get the best product for your needs.
MaterialThe material of thermal underwear is crucial because it affects warmth, moisture-wicking ability, and comfort. Common materials include synthetic fabrics like polyester and nylon, natural fibers like merino wool, and blends. Synthetic fabrics are lightweight, quick-drying, and good at wicking moisture, making them ideal for high-intensity activities. Merino wool is excellent for warmth, odor resistance, and comfort, making it suitable for both active and casual wear. Blends combine the benefits of different materials. Choose a material based on your activity level and personal preference for comfort and warmth.
WeightThermal underwear comes in different weights: lightweight, midweight, and heavyweight. Lightweight thermal underwear is best for mild to cool conditions and high-intensity activities where you generate a lot of body heat. Midweight is versatile and suitable for a range of temperatures and activities, providing a balance of warmth and breathability. Heavyweight thermal underwear is designed for very cold conditions and low-intensity activities where maximum warmth is needed. Select the weight based on the climate you'll be in and the type of activities you'll be doing.
FitThe fit of thermal underwear is important for both comfort and performance. A snug fit is essential for effective moisture-wicking and insulation, as it helps trap body heat and move sweat away from your skin. However, it should not be too tight, as this can restrict movement and cause discomfort. Look for thermal underwear that fits close to your body without being constrictive. Consider your body shape and the type of outer layers you'll be wearing when choosing the fit.
Moisture-WickingMoisture-wicking is the ability of the fabric to draw sweat away from your skin and allow it to evaporate. This is important because it helps keep you dry and comfortable, preventing chills from damp fabric. Synthetic materials and merino wool are both good at wicking moisture. If you plan to engage in activities that cause you to sweat, prioritize thermal underwear with excellent moisture-wicking properties to stay dry and warm.
Odor ResistanceOdor resistance is a feature that helps keep your thermal underwear smelling fresh, even after prolonged use. Merino wool naturally resists odors, making it a great choice for multi-day wear or activities where you might not have the opportunity to wash your base layers frequently. Some synthetic fabrics are treated with antimicrobial agents to reduce odor. If you need thermal underwear for extended use or intense activities, consider options with good odor resistance.
DurabilityDurability refers to how well the thermal underwear holds up over time and with repeated use. High-quality materials and construction will ensure that your thermal underwear lasts longer and maintains its performance. Look for reinforced seams, high-quality stitching, and fabrics known for their durability. If you plan to use your thermal underwear frequently or in rugged conditions, prioritize durability to get the most value from your purchase.

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