It is important to ensure you keep warm and properly insulated during the cold season for comfort and to avoid illness. Thermal Underwear is very important for keeping you warm but, it’s still an underrated accessory that add value to cold weather layering.  With the right cold weather thermals, that tingling which is sometimes painful, that you feel on your legs and thighs will no longer bother you.

Plus, the best winter underwear is so thin that you don’t feel it nagging under your clothing but offers the best breathable warmth. I’ve listed below the 10 best long underwear in 2020 so you can pick your choice or choices to keep you warm this winter.

How To Choose The Best Base Layer – Buying Guide



The warmth and insulation that your base layer provides is a critical feature to look at. Obviously, there are variable existing levels of warmth that thermals provide depending on the material and construction. The Duofold brand for example, has their thermals ranked from warm to warmest underwear and their functioning level varies from working in cold to extremely cold weather.

The warmth level also depends on where and how you plan to use your underwear. Are you simply sporting them indoors as warm indoor wear? Are you using them as layers? Base or mid? And where exactly – commuting to work or at the backcountry? All these questions answer your big one – how warm should my underwear for low temperatures be?

Wool, for example Merino offers excellent warmth and normally makes some of the best underwear for extreme cold, due to its high thermal properties. The warmth provided also varies with the weight of the wool, ranging from 200 to 300 g.  The more the weight, the more insulating the wool is.

Synthetic material such as polyester and nylon when combined with other fabrics also do an excellent job at retaining your body temperature. The best combination and construction for high thermal and heat retaining properties when it comes to synthetic material is combining the synthetic polyester and natural cotton.

A double layer of cotton and polyester insulation provides an excellent thermal solution.

Keep in mind however; the focus should not be on how warm the material is only. You need to think of functionality, sure the material is warm, but is it functional? For example, when you think of the backcountry, you obviously think you need heavy-weight underwear.

However, you are probably there to ski or snowboard, meaning you will be indulged in active sports. Thus, you want fabric that is thick and warm however you don’t want something to weight you down plus you want a fabric that is stretchable and breathable so you are comfortable and able to move respectively – which takes me to the next feature!


Breathability is another important feature that ensures you are comfortable all day long as well as odor from perspiration is neutralized. So the next time you are shopping for underwear remember to look for moisture-wicking properties. Moisture-wicking properties complement breathability, the concept basically works by having a fabric that is capable of absorbing moisture and sweat from the body and let it out without compromising the body heat retaining qualities.

Some thermals are constructed to complement this quality with odor control – which also trap odor from sweat and neutralizes it. For base layers especially, you need fabric that is efficiently breathable because your thermals have contact with skin and are the first layers to put on. Synthetic material such as polyester and material such as silk bear excellent moisture-wicking properties and as such, combined with their heat retains characteristics, work perfectly as base layers.

Natural material such as wool for example, is excellent heat retainers and insulators but bear an unfortunate weak moisture-wicking ability. So though, they [provide excellent insulation, they don’t make ideal base layers. Woolen underwear therefore, work best as mid or outer layers.

However, if you want to use them as base layers, they work okay with minimal outer clothing or try to pair them with lightweight and breathable outer clothing. Combining natural material and synthetic ones such as polyester and cotton also enhance moisture-wicking properties.


You are probably going to be wearing your long johns for a prolonged period of time, thus, comfort should also e a priority. Ensure your material is warm enough but also breathable.  For those with sensitive skin, a thorough scrutiny of material is required –you don’t want to invest on a woolen underwear is you have sensitive skin!

Manufacturers keep adding more and more features that induce functionality and allow enhancement of comfort – at the end of the day it contributes to making your thermals comfortable. Some of the common features manufactures incorporate in their construction include;

  • Convenient front-fly on base layer pants for men to allow for easy relief
  • Contoured and Tagless waistband with minimal chafing and itching
  • Elastic knit cuffs
  • Stretchability
  • Light-weight finish
  • Use of silky soft and smooth fabric
  • Snug fit design
  • Zipper pockets and hoods

It is also advisable to examine individual choices so you can pick up on what you are looking for in terms of comfort. The activity and where you intend on using your thermals also affect your decision.


Style on underwear for low temperatures varies with construction and intended use for your underwear. The best men’s underwear for example tend to be form fitting but more straight than curving, if you are going for the tight-fitting option. Womens thermals on the other end are curvier form-fitting with a focus on thighs.  Gender based style also differs with features that necessarily work for one gender but doesn’t for the other.

Majority of Mens base layer pants are fitted with convenient front-fly but Womens aren’t because they don’t need them. The best women’s thermal base layer top also feature feminine designs such as see-through, tight-fitting, curvy construction and the choice if silk as material, such as the Terramar Women’s base layer. Though snug, thermal leggins for women tends to be more body-hugging than those of their male counterparts.

Additionally, underwear for low temperatures are commercially available as one-piece set of thermal full suit or 2-piece set with a top and bottom. The two-piece set are normally manufactured and sold together or individually. Both styles however, should be snugly tight fitting.


Underwear for low temperatures should be tightly fit to ensure effectiveness.  Womens thermal leggins tends to be more body-hugging than Men’s ones due to the natural physique of the two. Nevertheless, ensure your underwear is tightly fitting. This is because the main purpose of underwear for low temperatures is to provide layer and insulation from the cold, thus, if there are gaps between the fabric and your skin, the cold is more likely to get through.

However, you don’t want the fit to be too tight that it makes you uncomfortable, you want it snug. Plus, tight clothing will restrict your circulation thus, bringing about the same problem of warmth – you body will not be able to effectively generate heat. Because thermals are mostly used as layers you want t go for the actual size because they are made slightly smaller than actual clothing to ensure they fit well.

Although, you exactly look or feel like a huge snowman, consider the complete product when you think of the underwear choice for your layering and the outer clothing. Effective yet light weight and thin underwear work best because they are effective at keeping yo u warm, they boast moisture-wicking properties, they won’t weigh you down and affect your mobility or ease of movement.


There quite a number of functional features to examine to ensure your underwear are of high-quality. However, the key points to look at are material, construction and overall effectiveness. Most good quality underwear for low temperatures like many other products will require you to dig deep into your pockets.

Remember though, expensive doesn’t necessarily mean functional. Obviously wool for example is more expensive than polyester, however, if you are looking for moisture-wicking thermals to wear for your next skiing competition, wool is probably not the best idea. However, that same good quality wool works great in extremely cold conditions for example threading snow on the rough terrains of K2.

Good quality underwear for low temperatures also boasts important and well-thought additions such anti-bacterial treatment, shape maintaining functions. Construction also impact quality of thermals. Designs such as flatlock seam knits and waffle knits enhance quality of the underwear by making them highly effective and durable.

Drying Time

Drying time is highly effected by the material used. Synthetic material for example takes less time to dry compared to natural material such as wool and cotton. Synthetic fabrics or natural-synthetic blends boast excellent moisture-wicking properties thus, they dry faster. It is therefore a better option to wear such fabric for high impact activities, even if you go for heavy-weight options.

For care and maintenance purpose, the problem remains the same. Cotton and wool like cold water washes and after that they require air drying. Avoid hang drying or machine drying because these processes tend to stretch and ruin their shape integrity. Drying the fabric on a flat towel accelerates the process due to the absorbing power of the towel.

Silk on the other end, is delicate but dries relatively faster than cotton and wool. Synthetic fibers dry quickly. You can wash them with warm water and throw them into a dryer machine and they will still come out fine. Dry hanging also works quite well for these fabrics.


Temperature rating varies with different thermals ranging from base layer for cold to extreme cold conditions. If you wake up with low temperature outside, the best thing to do is to wear your long underwear. Depending on your area’s weather forecast, you will decide whether to wear light or heavy weight longs johns. Generally, the following guide helps;

Ultralight weight – low temperature at least 23 to 18 degrees Celsius for mild to cool conditions

Lightweight – cool to moderately cold temperatures when somewhat active

Midweight – moderately cold to cold temperatures

Heavy weight – extremely cold temperatures in thick heavy snow or icy days


Durability is also affected by construction design and material. The material needs to be strong enough to withstand the functions of the thermals. You also want strong sealed seams to ensure long-lasting function. It doesn’t hurt if your long johns are finished with a sturdy construction either, however, it should be functional enough to allow for movement.

Manufacturers of good quality underwear for low temperatures also add features that are functional and also enhance durability of the underwear. Low density on the fabric is a good example. Lower density fabric maintains shape of the underwear by trapping air between the layers, thus, the pants are able to function with minimal space and flexibility.

Other important features include anti-bacterial and anti-fungal treatment which protects our thermals against their attack. A proper fit on your underwear also means they are functional and will not be overstretched thus cutting down their usage time. Car and maintenance as well as wearing habits also affect durability.

As mentioned, for example, material such as cotton and wool, need not be washed with warm water or dry hung, this destroys the shape of the underwear thus, undermining its function and eventually affecting durability. You want to also consistently wash your underwear and if for some reason, they get soaked, immediately remove them and dry them. Never wear soaked underwear for low temperatures!


Odor control on your underwear is also an important feature to have.  The control of the odors most definitely goes with breathability and moisture-wicking properties. Odor control works by the fabric absorbing odor from perspiration or moisture and then neutralizing it to ensure your body is fresh smelling and dry. Thus, material with poor breathability may not be as effective as should be at this function.

Controlling odors also helps eliminate bacterial and fungal attack because your body is kept fresh, dry, and non smelly. It is key to have underwear for low temperatures with this ability especially when engaging in high-energy physical activities. If you wear underwear for low temperatures without this ability in the cold weather and not partake any active engagements, they might just work for you – but I mean who doesn’t want this feature in their underwear for low temperatures?



Q: Should Thermals Be Tight Or Loose?


To ensure maximum effectiveness, thermals that work as base layer should be fitted tightly. You don’t want space between the fabric of you thermals and your skin because this will most certainly let the cold air through thus leaving you cold.

However, you want the fit to not be too tight. It should be a snug fit.  Long underwear that is too tight will disrupt blood circulation, therefore, preventing your body from generating enough heat, thus, their work will be in vain and will not retain enough heat to insulate your body.

The base layer and skin act as the thermal barriers and they require very little space to accommodate the heat of your body. So always remember a snug fit not restrictive! Keep in mind to always go for your actual size of base layer thermals because they are normally made to be a size lower than your actual outer clothing so as to achieve the snug tight fit.

Additionally, if you plan on using your thermals as mid-layers or outerwear, a regular fit will do. The key is to ensure their fabric is insulating enough. As mentioned before, wool underwear, for example, makes an excellent mid-layer or outerwear. This is because wool boasts excellent thermal properties, thus, on its own, it provides excellent warmth in heated indoors during cold weather or mid-layer with minimal outer clothing in the outdoors.

Q: Should You Wear Underwear With Thermals?


Absolutely. Thermals do not work as alternatives to undergarments, their function is to insulate and add warmth as a layer to the body. For hygienic purposes, it is also highly advised to wear thermals over undergarments. Plus, it’s a win-win situation; wearing underwear adds even more layers of warmth to your body. I, for one, want a warm behind during cold conditions.

Q: Synthetic Or Wool?


Wool boasts extremely high-thermal properties and according to as its weight increases so does the thermal abilities. However, wool is not an excellent moisture-wicking fabric. Because it is highly insulated, the fabric does not effectively let moisture or sweat evaporate out easily.

A synthetic material such as polyester or nylon on the other end also boasts high thermal qualities but not to the depth of wool functional thermal qualities. Many synthetic materials on the other end, carry very efficient moisture-wicking abilities. Synthetic materials are good at moisture-wicking because of their fabric construction – many synthetic materials simply have the ability to hold moisture longer in their pores between individual strands (wool can’t) before slowly letting the moisture leave the fabric membrane.

Thus, when deciding which material works for your long underwear, it begs the question – where and how are you going to be using it. Synthetic material works well as a base layer and depending on the construction whether –light-weight or heavy-weight, the fabric suffices to insulate your body.

Additionally, synthetic material such as polyester is more durable and better at odor control than wool. So the material can take on the harsh function of base layers. Synthetic material is also cheaper, so you can get the best material for a fraction of its natural wool counterpart.

Wool on the other end works well as a mid-layer or outerwear. As a mid-layer, it boasts quite dependable thermal abilities, so not having to worry about skin moisture absorption, it works great. Additionally, because wool is so warm, minimal outer clothing is enough, so you will get that breathability.

As outer clothing, especially when rocking that woolen underwear set in your leaving room, it provides enough warmth.  This doesn’t mean that wool is not a good base layer – we can definitely say it makes good material for the best base layer for cold weather. I guess its gifted insulation ability also makes it its prime enemy.

The activity also gauges what one should wear. You want something very insulated yet breathable in the cold when active whilst you can go for super warm even none-breathable in the extremely cold and frigid weather especially when you are inactive. If compared to cotton, wool can actually withstand moisture for some time without being damp and useless – so if it’s extremely cold on that cross country ski trip, woolen thermals won’t hurt!

Globo Surf Overview

The long underwear reviews above prove their unbeatable importance and versatility. You can rock these bad boys, as layers or alone a really comfortable and cozy sleep or lounge wear. And don’t get me started on their functional features, from elastic knit cuffs that enhance heat retention and allow mobility to anti-bacterial treatment to ensure you are always protected.

Their ingenious nature adds that feeling of style – whether you want to choose a pair for your next skiing trip or your next outdoor concert. The price is also very appealing – with the features, quality and value the 10 best underwear in 2020 listed above bring, they are definitely a bargain. With options available for both men and women, you just cannot afford to not get your choice!

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Globo Surf
My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!