Best Thermal Underwear Union Suits for Men of 2026

"I honestly didn't expect these Amazon Essentials long johns to impress me so much—they're super warm, lightweight, and really comfortable. For the price, you can't beat the great quality and value. After my first order, I picked up more because they're perfect for layering in cold weather or just lounging at home."

"After seeing the price of name-brand thermals, I went with these instead and was very impressed with their softness, warmth, and fit. I wore them camping in the Rockies and plan to take them skiing, too. The value is unbeatable, though I'm keeping an eye on the waistband's elastic durability over time."

"These long johns remind me of the old Coleman ones I’ve had for years—thick material, quality seams, and a true-to-size fit. They get me through winter and keep 'ol Arthur' (arthritis) at bay. Highly recommend for warmth and comfort!"

"I’m glad I ordered this union suit despite some hesitation. The regular Large fits me perfectly, and I appreciate the waffle weave fabric—lighter than some but warmer than a t-shirt. The snap closures are secure with no gaps and make it easy to put on and take off. The new back flap design is clever and much more comfortable than the traditional vertical slit; it’s easy to use and avoids mess. While the price is a bit high, the comfort and versatility make it worthwhile for layering or pajamas during cooler months."

"As someone who’s never owned a union suit before, I was impressed with the Carhartt quality and construction. The extended cuffs make layering seamless, and the button-up design is well thought out, allowing easy on and off with good coverage. I love that it’s warm yet not too bulky, so I can move freely while working outside in freezing weather. The suit also provides extra arm and leg length, which prevents sleeves and pants from riding up."

"I absolutely love this onesie! It’s reversible and features beautiful, easy snap clasps. The elastic back flap is much more flattering and practical than buttoned designs, making it easy to use and more comfortable. For my size, the fit is just right—snug at the thighs and relaxed at the calves, like pajama pants. The fabric is soft, textured, and keeps me warm, making it perfect for cold season layering or sleepwear."

"I'm 6'4" and about 250 lbs, and the XXL size fits me perfectly. The material is super soft and warm, and although there's a bit of looseness around the midsection, it's not an issue. The only minor challenge is with the buttons, which are a bit tricky for me—hopefully they get easier over time. Overall, I’d recommend these pajamas!"

"I purchased these as a Christmas gift for my grandpa, and he was thrilled! He'd been reminiscing about his old long johns, and these brought back memories. The Ekouaer fabric is incredibly soft and comfy, which he loved!"

"My grandson absolutely loved this set. He found them comfortable and warm, but not too hot—in fact, he barely wanted to take them off. I’d definitely recommend this for others looking for a great gift."

"I use this union suit for both Halloween costumes and as a base layer during hunting season and winter outdoor activities. It fits my son well and he absolutely loves it. The suit is warm, comfortable, and perfect for layering under clothes in cold weather."

"I'm 5'7" and 190 pounds, and the fit is snug but flexible, with just a bit of extra length in the legs. The material is super comfortable and the suit is easy to move around in, even with my broad shoulders. The legs do bunch a little at the ankles, but it's not a big deal. Overall, I'm very happy with these long johns!"

"As a caregiver for my husband with Parkinson's, I appreciate that these are soft and gentle on his sensitive skin, and they help regulate his temperature without overheating him. He finds them warm, comfy, and easy to wear, and I think he looks adorable in them! They're also lightweight enough for comfort but provide enough warmth for chilly days."

"I was really happy with these—the fit was perfect and they’re super comfy for layering during winter. The material is light, stretches well, and doesn’t roll up. I got a size up and that was just right."

"Customer service truly impressed me! When one of my union suits had a button issue, the company quickly responded and sent me a replacement with Velcro. Their pajamas are fantastic—definitely recommending to everyone."

"Sizing was way off for me. I normally wear 5XL, but these were so tight I couldn’t even get them on, while other brands fit me loosely. If you need larger sizes, this may not be the best option."

"I bought these for my husband since he works outdoors, and they've proven to be exceptionally warm and comfortable without feeling bulky. He wears them all day beneath his work clothing, and they provide superior warmth compared to regular long underwear. The material has remained soft and true to size, wash after wash. I recommend these as reliable cold-weather layers for anyone working outside."

"As a medium-built guy at 5'10.5” and 158 pounds, I ordered a small based on other reviews, and the fit is spot-on with no saggy crotch or uncomfortable waistband. The ankle cuffs are snug but perfect for boots, and they provide great warmth for winter and hunting activities. My only minor issue is the small fly opening, but after a simple adjustment, they’ve become my go-to thermals—so much so that I now own six pairs!"

"I wear a 34x34 in pants and found that the XL size fits perfectly. These thermals feel even better than I expected—thin, not bulky, yet incredibly warm. I was so satisfied after trying them that I immediately ordered more."

"I've been using the Heated Thermal Underwear and Socks Set during winter, and it's honestly a game-changer for staying warm outdoors. The material is super soft and comfortable, and the heating elements are evenly distributed so I get warmth exactly where I need it. The USB feature is a huge convenience since I can plug it into a power bank on the go. The socks are thick and the heat kicks in fast, which is perfect for chilly days. Easy to wash and maintain too—I'm genuinely impressed and would recommend this set to anyone who wants to stay warm!"

"Living in a place where temperatures drop below zero, I needed something reliable for the cold. These thermals heat up quickly and work with different power banks, which means I can swap out batteries and stay warm longer. The fabric is thick and soft, though the fit is a bit snug, which I expected. The only thing I’d change is the socks using regular batteries—it’s a bit less convenient. Still, this set has made winter much more bearable for me."

"The pants and sleeves are shorter than I’d like, but the quality and heating ability exceeded my expectations. I'm 6’ tall and ordered a large, and while the fit could be longer, the overall warmth and comfort are impressive. If you don’t mind a slightly short fit, these are a solid choice for staying cozy."

"I'm glad I found this set—it's lightweight yet keeps me warm and is perfect for layering in cold weather. Even though it's a bit pricey, I think it's worth the investment since it lasts a long time if cared for properly. My husband's second pair has lasted over a decade!"

"To be honest, I’m not sure it works as expected. The fabric isn’t very silky and feels a bit catchy, so I worry that clothes might not drape smoothly over it and could look a bit odd."

"I got these for my boyfriend who works outside, and he absolutely loves them. They keep him warm without being restrictive, and he even likes lounging in them at home. The fit is great for his tall, skinny frame, and we plan to buy more soon!"

"This has become my go-to winter underlayer because the fabric is incredibly soft and warm, yet not bulky at all. The seams and buttonholes are well made, and there's been no shrinkage or pilling after several washes. If you’re a 2x with long arms, you might want to double check the specs, but overall I'm thrilled and don’t want to wear my old brands anymore."

"As someone who wears bib overalls a lot, I really appreciate that these union suits don’t have tight elastic waistbands. The fit is comfortable even with my belly, and the rear flap is easy to reach, making restroom breaks convenient. I like how the sleeve cuffs hold in place and keep the cold out, and there's plenty of room for movement without stressing the seams."

"I’ve put these base layers through all sorts of activities—from camping and fishing to snowboarding and work—and they’ve held up incredibly well. For just $13 a set, the durability and comfort beat out many pricier brands. I’m 5’10” and 180 lbs, and the large fits me just right. If you want a solid, reliable base layer, these are a fantastic pick."

"I took these on a ski trip where temperatures dropped to -11°F, and they kept me warm and comfortable. I even bought a second pair after trying them out. The insulation and layering ability are impressive, and even after active days, they didn’t retain odor. I’ve washed them several times and the quality remains excellent."

"These base layers are extremely warm and cozy—perfect for my trip to Alaska. Just be aware that the sizing runs small, so order up for a better fit. I was impressed by the high-quality material and construction, which kept me comfortable in freezing weather."