Updated October 9, 2020
Winter can be harsh, but one thing that can help make it a little bit easier is to get yourself some warm and comfy long underwear. Thermal clothing gives you an extra layer of insulation, whether you will be hitting the slopes, the office, or just taking your dog for a walk. Base layers come in a wide variety of material from silk to merino wool to polyester fleece in a range of thickness and levels of warmth. Thermals are often sold as sets, but you can also buy just tops or bottoms that are sold separately. You can wear thermal underwear under casual or work clothes, jeans, or snow pants, depending on whatever activity you are choosing to do. Read on if you are interested in learning about some of the softest, most comfortable best-selling long underwear to keep you warm.
Thermajane Women’s Ultra Soft Thermal Underwear Set
If you aren’t looking to spend a lot on your thermals, check out Long Johns Set from Thermajane. This is a popular option on Amazon as it is very budget-friendly and is a suitable thickness to be worn under jeans, leggings, or snow pants, so they are pretty versatile. They will keep you warm, and they are ultra-soft and comfortable. You need to be careful with sizing on the Thermajanes and double-check the sizing chart of the manufacturer since the sizing isn’t super extensive, so the fit can be a little off if you fall outside average sizing. You can get the Thermajanes in eight colors, the material is fleece-lined polyester, so it is durable and washes and wears well. Most women find this style to be a good deal that is comfortable to wear all day. Since they are fleece-lined, they are quite thick, with the outside of the fabric being a little bit slick, so it doesn’t bind or bunch up with what you are wearing.
Available from Amazon
Uniqlo HEATTECH Line
The Uniqlo HEATTECH Line of thermals is a popular option for a lot of people to wear under regular clothes. They aren’t really warm enough for lengthly outdoor activities, but they are great to wear in the winter under dress or casual outfits. Uniqlo has different levels of thickness for their HEATTECH garments that may be more suitable for colder situations, but the best use is as a base layer to add a bit more extra warmth to your regular wardrobe. They are pretty lightweight and soft, so they are super comfy to wear. The other great thing about the HEATTECH line is that they don’t add any bulk and are so thin (yet warm) they feel great against your skin and aren’t noticeable under your clothes.
Available from Uniqlo
Helly Hansen W HH Lifa Merino Pant
An excellent sweat-wicking fabric that works well for thermals is merino wool. Don’t be scared off by the idea of wearing wool as a base layer; merino wool is known for being soft and not at all itchy. It is also excellent for moisture-wicking, being an excellent insulator, the ability to regulate body temperature, as well as being odor-resistant and super breathable. If you are looking for a design that is a little bit more high performance that will keep you warm even on the nastiest winter days, you should have a look at the Helly Hansen W HH LIFA Merino Pant. This popular Helly Hansen base layer uses merino wool combined with Lifa® Stay Warm Technology and is a perfect base layer if you spend a lot of time outdoors in the cold weather. They are reportedly very comfortable and do not itch at all. If you are looking for a set, you can try the “W HH LIFA Merino Crew” that will work nicely with these bottoms. They come in a few beautiful colors with a cool strip down the side.
Available from Moosejaw.com
Smartwool Merino 250 Baselayer
Another great place to find merino wool products is Smartwool. They have two thicknesses for their thermals the 150 or the 250. The 250 base layer is the more popular style since it is warmer and is often used for activities that you do in the snow like skiing or snowboarding. They are a bit expensive, but like some of the other the higher-end options, they will last for a long time, and most women find that the benefits are worth the cost. The fabric is very soft and easy to move in; they don’t create extra bulk or bind uncomfortably in any area. The mid-weight merino fabric has all of the benefits of merino, including regulating your body temperature as well as being breathable and odor-resistant.
Available from SmartWool.com
Lands’ End Women’s Silk Thermals
If you are looking for silk options, you may want to try the Lands’ End Silk thermals; these are one of the more popular silk thermals that have been around for a while. Not surprisingly, the silk styles are some of the most comfortable, but they come with a little bit of a higher price tag. Silk is an excellent fabric for thermals because it is thin so you can wear them under work clothes that you may wear to the office, and is an excellent insulator. The other great thing about silk is that it can wick sweat and is breathable so you won’t get too hot, giving you that extra level of comfort. The Lands’ End Silk thermals won’t add any bulk to your look, and the silk is super soft against the skin. The tops, bottoms are sold separately, and they come in a few classic colors.
Available from Lands’ End
Arc’teryx Rho LT Bottoms
The Arc’teryx Rho LT Bottoms are one of the most highly regarded lightweight thermals that are designed for “lower output” winter activities, which I think means things like walking or just wearing under your clothes. Women love this style because it does a great job of regulating your body temperature, so you don’t overheat or feel cold when wearing them, despite them being so lightweight. The material is also very breathable. They are made from something called Torrent™ fleece that has been brushed for extra softness. The fleece is also able to maintain its shape even after a lot of wear (some long johns tend to get a little sagging after a bit of use). The other notable feature of this style is that it is an especially good fit for most women, especially if you have an athletic shape with strong muscular legs. Overall these are high quality, thin enough to wear under regular clothes, have an excellent stretch to the material, and are well-fitting for most women’s bodies.
Available from Arc’teryx.com
LL Bean Silk Pointelle Pants
These LL Bean Silk Pointelle Pants are another well-known silk style that women go back to year after year. They are loved for being super-thin and very warm. The weight of the fabric is so thin that they are comfy and easy to wear under almost any type of clothes, making them an excellent option for office attire. The L.L. Bean silk thermals are not only soft against the skin, but they are also very durable, so you can expect several years of wear if you end up purchasing this style. A lot of women love this style for travel since they don’t take up much room when packing, and you can wear them as PJs if you need to. They are also easy to hand wash and dry while traveling. If you are interested in the silk styles, just keep in mind that they are great for wearing under regular clothes for a bit of extra warmth, but they really aren’t warm enough for prolonged outdoor activities where you are going to be in very frigid temperatures.
Available from L.L Bean
Icebreaker Women’s Merino 200 Oasis Leggings
The Icebreaker Women’s Merino 200 Oasis Leggings are one of the best styles if you are looking for a seriously warm, high-performance base layer that is designed for changing conditions of winter sports activities. They are merino wool, so they will keep you warm but also wick sweat away and help regulate your body temperature if the weather gets too hot or too cold.
Available from Backcountry
Sweaty Betty Ski Seamless Base Layer Leggings
If you would like a little more flair in your long underwear Sweaty Betty Ski Seamless Base Layer Leggings may be the style for you. This is another design that is super functional as a heat regulating base layer, but it also has the bonus of being fashionable and suitable enough to wear on their own. These are a ski base layer, so they are designed to be warm. You can buy just the bottoms, but they also have matching tops to make a set. The leggings are super soft and easy to move around it. One thing to be aware of with the Sweaty Betty leggings is that they are pretty high waisted. Some women love this, but if you have a short waist, they probably aren’t the best option for you.
Available from SweatyBetty.com
Cuddl Duds Fleecewear Stretch Leggings
If you aren’t totally sold on the idea of long underwear or don’t want to add anything new to your closet, some women just wear comfy leggings under their clothes or snow pants. If you don’t have a warm pair of leggings, a comfy style that is very popular and comes in fun patterns are the Cuddl Duds Fleecewear Stretch Leggings. Cuddl Duds do make thermals, but the more popular option is their Fleecewear Stretch Leggings. They are a little more substantial than regular leggings and are warm. Women love Cuddl Duds not only for the warmth but they generally have an excellent fit nice around the waist and are fairly flattering for most body types.
Available from Kohl’s
Things to Keep in Mind When Shopping:
Fit– Most people like a comfortable yet close fit with thermals. If the fit is too loose, then the garment may be bulky and uncomfortable in certain areas and look odd, depending on what you are wearing. You want your thermals almost to be a second skin that you don’t even notice you are wearing.
Material– The fabrics for long underwear can range from a knit cotton to silk to the latest ultra high tech high-performance fabrics. Polyester blends are generally the cheapest fabrics, silk options can be relatively pricey, and if you are looking at the high-performance options that are great for outdoor activities like skiing, they can get pretty expensive.
Thickness– If you are planning on wearing your thermals under regular work or dress clothes, you will want to check out Uniqlo or some of the super-thin silk options, that cling to the body, and are soft and comfy to wear. If you don’t’ want to spend a lot of money, you can check out polyester or fleece styles that will be warm, but they will be a bit thicker and maybe not appropriate to wear under all types of clothes. The high-end, high-performance options are usually pretty thin but super warm.
Color- These days, you can get thermals in a much wider variety of colors than just your basic black or white. If you want a colorful option check out the Thermajanes, Smartwool, or Cuddl Duds listed above.
Size– Since the sizing of long underwear is pretty limited for the most part falling into xs, s, m, l, and xl, you will need to be very careful when you choose your sizing. Make sure you read reviews and check any sizing charts that are available carefully.