Best Thermal Underwear Bottoms for Women of 2025

"I got these in black and red in size XS, which was recommended. They fit perfectly, feel smooth under jeans, and are warm. They wash and dry nicely. I got them on sale and am very pleased with my purchase. I will probably buy more!"

"I bought two pairs of these long underwear for the cold weather. They fit snugly, are soft yet thin, and keep me warm. I wish they were about 2 to 4 inches longer to cover my ankles, but the high rise keeps my stomach covered. For reference, I'm 5'3" and 135 pounds, and the size small fits me perfectly."

"These long John's exceeded my expectations! I needed something for extra warmth while working outside. They are smooth on the outside and have a fuzzy warm layer on the inside, providing just the right protection from the wind and cold. They fit like leggings and allow for easy movement. I highly recommend these for anyone needing added warmth this winter!"

"I found these to be very comfortable. I had to size up from my usual L to XL since they run smaller and may shrink a bit. They are soft and perfect for lounging around during COVID. I liked them so much that I bought six more pairs!"

"I really love these long underwear! They are lightweight, sturdy, and fit well under my dress pants. I bought a size 4X and it fits perfectly. I would definitely buy them again!"

"I was disappointed with the quality. They felt itchy and flimsy right out of the bag. There was even an unstiched seam in the calf area. After washing, they still had a chemical smell. Overall, it was a poor experience for me."

"I initially bought a medium, but it felt too small and tight around my thighs. I'm 5'7" and weigh 120 lbs. I returned it for a large, and it fits perfectly. The 100% cotton material is very comfortable, and I highly recommend it!"

"I was concerned about ordering this thermal underwear due to some reviews. When it arrived, I thought the length was too long, but after washing, the fit was perfect for me at 5'3" and 120 lbs. They are soft, comfortable, and warm. The only thing I would change is the stiff label near my waist."

"I bought these thermals to wear under my jeans in the cold Montana weather, where we need thermals for about six months. Unfortunately, I had to return them because the fit was awkward. I'm 5'6" with a slim to normal build, and the waist was too high and tight, while the legs felt baggy."

“I find these thermal bottoms very soft and easy to layer under my jeans or work uniform. They provide a small amount of warmth, which is perfect for chilly days. I appreciate that they fit true to size and hold up well after at least 10 washes. Overall, I feel they are good quality for the price.”

“These leggings are AMAZING! They keep me warm down to 35 degrees when I wear them under my work jeans. I ordered the XXL size, and they fit just right. I suspect there might be some confusion with different versions of these leggings, but I assure you, the correct item is worth it, and I plan to order a third pair!”

“These leggings serve their purpose well. They keep me warm without being bulky under my pants, and I find them very soft and comfortable. I ordered an XL size, and they fit perfectly.”

"I’m 5'9" and 123 lbs, and the XS fits me well. They’re comfortable for sleeping. If I wear them out, I’ll use them as tights since they aren’t as form-fitting as yoga pants. The waistband is a bit stiff, but overall, a good buy."

"At 5'6" and 165 lbs, I found the medium fits nicely. I could’ve possibly gone for a small since I prefer a tighter fit under my leggings. The medium top I got is perfect, snug without being tight. I wear this for my morning walks and keep it on all day. The fabric is super soft and comfy."

"I absolutely love these! They do have a waistband, but it’s quite loose, which is fine. I just wish the waistband was thinner. They are warm and light, and I really appreciate how they fit under my jeans."

"I live and recreate for long hours outdoors in Duluth, Minnesota. I've liked Devops' tops as low-cost baselayers for a while, but I hadn't gotten leggings yet. They work really well as a thin baselayer under tighter pants, adding just a touch of warmth. One of the best aspects is their smooth exterior and fleecy interior; work pants and other pants slide right over them without bunching up. They're perfect for layering across various conditions, whether under office slacks or unlined hiking pants in chilly weather. Overall, I highly recommend these leggings as incredibly versatile base layers for the price."

"These are the softest, warmest, and thinnest leggings I’ve ever purchased. I can wear them under my tight jeans comfortably! I'm definitely planning to buy more pairs to keep stylish and warm throughout the winter!"

"While I appreciate the thinness and warmth of the fabric, I've noticed they run small and the rise is a bit short for my liking. I had high hopes for these leggings, but the fit isn't quite what I expected."

"At 5'7" and 130 lbs, I purchased the small top and bottoms. These are fantastic! Warm, light, and wear exceptionally well. They don't retain odors after multiple wears, wash nicely, and are super flattering in black. I bought these for my trip to Patagonia to trek and chose them over my other options. Highly recommend for anyone active!"

"These long underwear are a perfect fit and thin enough for comfort under all my pants. I can't get through winter without a base layer, and these meet that need wonderfully."

"I was looking for very lightweight ultra-thin leggings for the change of seasons when I only need a slight layer. They are not for winter but provide just the right warmth for fall. The pants are long enough to cover my ankles and feel very comfortable to wear."

“I was amazed at how warm these leggings are. They feel magical—thin yet incredibly cozy! Plus, I absolutely love the color.”

“These leggings have become my go-to for hiking in the mountains. They are super comfy, and I appreciate that they’re not see-through while also avoiding the camel toe issue. I’m thrilled with their durability even on tough trails!”

“While I was slightly disappointed in the thickness of the fleece lining, I still find these leggings very comfortable. They fit well under my jeans during the winter. I’d recommend them, especially for anyone seeking a base layer.”

"I find these leggings fit pretty true to size. I can easily wear them under my jeans or other leggings, and they keep me warm when it's cold out. They are thin but do their job."

"I absolutely love these! I work in a cold environment and bought them to keep my legs warm. They work great, though I would recommend buying one size smaller. After about four washes, they are still holding up well."

"These leggings are so warm and comfortable! They are not bulky, and when I wear them, I feel cozy without needing larger pants. As soon as I put them on, I feel the warmth immediately."

"I find these undergarments to be just what I wanted: smooth, silky, and incredibly lightweight, while still being warm. I wear them at home under my sweatpants, keeping the thermostat low, and they’re thin enough to wear out under jeans. I highly recommend them!"

"I absolutely love these! The material gives them a slightly dressy look, which is perfect for my workdays. They are lightweight yet warm, making them ideal for various occasions."

"Although it's still too warm outside to test the warmth, I can say that the fit is really nice. They are certainly comfortable!"