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Thermal Underwear buying guide

Want to add an extra layer of protection from the icy-cold temperature? Invest in suitable thermal underwear and give your body proper insulation.

The product provides adequate warmth and is quite comfortable. You can wear them directly over your skin or add layers beneath it for extra comfort and insulation.

While selecting a product, you have to look into certain factors. You have to deem about the material, style, fit, size, and other additional properties.

Gathering all the details on these characteristics can become a strenuous task. Moreover, you may end with wrong information.

A comprehensive buying guide provides you all the necessary information under one roof. You can quickly go through them and funnel down the best option for yourself. You also get answers to various common questions and queries.

What do you mean by Thermal Underwear? Why do you need them?

Winter is a season of snow, the dominance of the color white, and much more. You don't sweat in the winter months that make it worth waiting for, but it has many disadvantages.

Due to the distance created between the earth and the sun, you don't have the soothing and warm sunlight to provide you protection against the biting cold.

It restricts you to leave your well-heated house and move out to run errands. To overcome these limitations imposed, clothing industries have done their best and presented you with a warm layer of clothing called thermal underwear.

It is made using warm fabrics that are closely knit. This knitting design helps retain your body heat and keeps you comfortable. There are multiple fine layers present that prevent the heat exchange, which may make you feel cold.

The skin of your body stays in close contact with this underwear and keeps you warm and cozy. You can wear other clothing essentials on top of this and continue working.

The significant advantage is that you can regulate the number of layers of clothes you want and keep yourself comfortable. You can use this clothing piece for winter outdoor activities or wear it at home or your office. It is a one in all solution to all your winter problems.

Let us start with a quick introduction and then move further into the guide.

Why should I read this buying guide before purchasing thermal underwear?

With several options available in the market, you can easily fall into the market's bear trap and purchase an ill-fitted product.

In this buying guide, you will get all the information in a well-structured way. It will save you valuable time, and you can strike down an ultimate product quickly.

So, without any further ado, let us dive into this immense pool of information.

Things to deem about while selecting appropriate Thermal Underwear

There are many variants of a winter warmer available in the market these days. Finding the best one in terms of price, quality, and the level of comfort offered makes your task quite challenging.

Though the retailers help you to some extent, their fake smiles and baseless claims can lead you to make a wrong investment.

To invest in the best thermal clothing and buy yourself long years of service, refer to this guide that we offer. You will find all the critical aspects that you need to consider. Gone are the days when you have to visit every shop or hunt for the same online.

Just sit with a cup of coffee and browse through this guide's pages. With accurate information and guidelines, you will be able to purchase the perfect winter wear for yourself and your family.

Hence, without wasting any more minutes, leave all your work aside and open this comprehensive guide to finding a suitable match.

Size and Fit

Picking up the right size and the perfect fit is essential when considering any clothing. These are no exception and need to be put under the scanner.

While searching for the winter underwear, make sure you look for the correct size. Note that it should be a size lower than your regular t-shirt size.

This one size down helps snuggly hug your body and leave no gaps in between. It ensures that you stay comfortable and warm. There is no heat exchange or the possibility of air entering from anywhere.

Also, ensure that the size you are opting for doesn't restrict your movement or hinder blood circulation. It should be comfortable enough to wear and move with.

The same goes for its fit as it should not be too tight or loose. The fit should be accurate and snug. While wearing thermal underwear, you might feel like you are stacked up with numerous layers of clothes because of the amount of warmth it provides.

It is incredibly lightweight and highly effective. The warmth you experience cannot be found in other winter underwear. Besides, these also absorb moisture and keep you dry.


Thermal underwear is made with winter-friendly materials. Its primary job is to keep you warm while in the snow with cold air hitting your face. These materials are listed below.

Before making your purchase make sure that you look at the advantages and disadvantages of these materials. Once you have gone through all the points, opt out the suitable one.

  1. Wool


It is a highly affordable material that is found in the majority of winter clothes. Merino Wool is the high-grade wool used to make this winter apparel.

It does not cause itching and keeps you comfortable. It's the excellent thermal properties of this material that makes it so popular.

It keeps you highly insulated and protected from the cold. This material does not get wet quickly, and this makes it a great choice if you are going out for skiing or snowboarding, where you are likely to sweat more.


Wool does not have sweat absorbing qualities. The lack of moisture-wicking properties does not work well when dryness is considered.

Though it retains heat longer, sweat can make you uncomfortable. Also, the secretion of sweat can make your underwear smell terrible because the wool retains odor.

  1. Synthetic


Synthetic winter wear is mainly made of nylon or polyester. Both of these materials are highly durable and have excellent moisture-wicking properties. These are very breathable and do not retain odor.

Cheaper than wool and lightweight, making them perfect to be worn as a base or outer layer. These materials are easy to maintain and clean.


Being highly breathable and moisture-wicking, these are not as effective as wool in terms of warmth. However, they can retain heat inside the fabric layers for a longer duration, unlike wool.


The warmth of your winter wear has a very significant role to play. After all, its job is to provide warmth and keep you comfortable irrespective of how cold it is outside. The material also influences the level of warmth provided by your base layer.

Thermal underwear is made of wool and man-made synthetic fibers. These are lightweight and offer an optimum level of warmth and comfort.

It is a predominant saying that heavy winter clothes enhance the amount of insulation and keep you warm. It is true to some extent because when you plan for skiing or snowboarding, you need to wear more layers to keep you warm. This adds to the weight and also hinders your activity.

Thanks to these lightweight garments, you stay incredibly warm and protected from the bone-chilling cold. You can also search for other variants to suit your functionality. Whether you want to wear these indoors or outdoors, you will always find something to opt for.


Since this garment piece will be staying close to your body for most of the time, many factors need to be considered when its level of comfort is discussed.

First and foremost, you should check the breathability of the material. Breathability helps you stay dry and doesn't retain odor. Also, check the fabric inside out if you are prone to skin allergies.

The increasing popularity of thermal underwear has led to an increase in the demand for improving the existing comforting features.

Some of the new features that are recently incorporated are listed below. These make your experience in the snow even more enjoyable and fun.

  1. Elastic cuffs

These take the shape of your wrist and cover it completely. Due to the presence of elastic, the cold air finds no way to enter inside.

  1. Stretchability

These are made stretchable so that they offer you a snug fit and are not too tight. It doesn't interfere with your body's blood circulation and provides comfort while moving.

  1. Zipper pockets and hoods

Zipper pockets enable you to keep your small essentials like smartphones, keys, ear pods, etc. so that your hands remain free. The hood protects your ears and head and gives a fashionable touch to your look.


The quality of any material holds the top priority while making any purchase. It is not limited to the material used, but other factors like the construction type, functionality, and effectiveness also contribute significantly to your low-temperature apparel.

Let's look at some of the quality influencing features that make a difference in your choice. These are mentioned below.

  1. Material

Wool is relatively more expensive than synthetic material. It doesn't mean that having a higher price makes synthetic material lower in quality than the wool. The choice of material depends on the use and not the price.

If you want to participate in outdoor activities, you might want to opt for a moisture-wicking material like polyester, synthetic material. Simultaneously, if you want enough warmth and dryness, you can always rely on wool.

  1. Construction type

If you have ever focused on your winter garments' design, you might have noticed some patterns. These patterns help increase the effectiveness and durability of your winter wear.

You will most commonly come across waffle knit patterns and flatlock seam knit. These, in turn, enhance the quality of your thermal wear.


Like the quality, the material and construction type also affect the durability of your base layer. Thankfully, thermal underwear is made using durable materials like polyester, nylon, and wool that are long-lasting and durable.

These apparel also features closed seams that prevent any airflow and keep the heat tightly sealed. Despite being made from such robust materials, they are very comfortable to wear and move.

These have low-density fabric that maintains its original shape even after regular use. Low-density material traps more air so that you stay warm for an extended period. Another feature that should be brought to light is the safety from microbial growth.

Wool and synthetic material prevent the growth of microbes and impart anti-microbial properties to your underwear. Thus, enhancing its durability. Due to the ability to keep microbes at bay, the fibers stay intact and don't get damaged.

Drying Time

Wool absorbs 30% more water than its actual weight. It can give you a rough idea of how much water it can soak and the time required to dry it. Moreover, it is not a breathable material, which again affects the time.

On the other hand, synthetic materials require less time to dry and so not soak much water. These are breathable that enables air to pass through and dry the fabric quickly.

Also, to keep the shape intact of the woolen ones, always opt for air drying. Machine drying stretches and damages the fibers. This, in turn, makes your garment unfit for use.

While on the other hand, synthetic materials can be easily machine washed and dried in the same. Hence, taking less time to dry.


The temperature determines which type of thermal underwear you should opt for. Keeping in mind the climatic condition of your area and the locations you are likely to travel wearing this garment, you should opt for the one that matches all the criteria.

An ultra-lightweight and lightweight base layer is ideal if your place does not cross the temperature range of 23 to 18 degrees celsius. You will experience a soothing breeze, and these variants are enough to offer the appropriate amount of warmth.

Moderate weight apparel is suitable for a place experiencing a moderately cold climate or a light snowfall. If you plan to go for backcountry skiing or snowboarding, you will be surrounded by a thick blanket of snow all around.

To give you adequate warmth and keep you safe, a heavyweight base layer is essential.


When retained inside your base layer, your body's heat generates so much heat that you start sweating even if it's snowing outside. Since our sweat contains body waste and minerals, it is undeniable that odor will be generated.

If your garment is not breathable enough, the odor will remain in it, making your base layer smell terrible. To negate this smelly trouble, thermal underwear is made from moisture-wicking materials like polyester and nylon.

These are highly breathable materials and have moisture-absorbing properties. These keep you fresh and dry without worrying about the odor. Besides, these also eliminate the problem of microbes and bacteria, forming colonies to create havoc on your outdoor trip.


Thermal underwear aims at providing comfort to all the people. Hence, the products manufactured are usable both by men and women. To match the individual needs and comfort, this winter wear has minor differences.

  1. For Men

In the case of men, you will find more of straight design. There is a front fly present in the underwear pants, making them convenient for their male customers. These don't have a body-hugging design and are super comfortable.

  1. For Women

The women-specific apparels have a curvy silhouette, unlike the male variants. These are body-hugging and feature many different styles like the see-through variant, silk fabric options, tight-fitting pants, and many more.

Besides the differences, these underwear come in a complete one piece or in a set of two pieces, which comprise an upper t-shirt and a pant. These have a snug fit and are very comfortable to wear.

Loose or Tight

A tightly fitting thermal underwear is preferred more over a loose one. The intention is to restrict the flow of air in and out of your apparel. Since a loose-fitting will let air quickly enter your warm shield and make you feel cold.

On the other hand, if you opt for a tight fit, this issue will be eliminated, and you will stay warm. However, very tight clothing should also not be worn. It will hinder blood circulation due to which you may faint or feel uncomfortable.

The best one to choose is a snug fit underwear. This is neither too loose nor too tight. It strikes the right balance and keeps you warm and comfortable. Always rely on these apparel's actual size because they are intentionally manufactured a size lower than the regular fit.


Thermal underwear comes in different designs that include the ones with short or long sleeves, round or zipped necks, and so on. The list is endless and will continue to do so as the designers are continuously improvising.

The sleeve and neck shapes can be chosen based on your layering preference. If you want to hide your base layer below other clothing pieces, you can always opt for a round neck with a short or long sleeve.

You can also opt for variants that have zipped high neck shapes. This shape is more useful for small kids who are active day-long and sweat a lot. They can easily open the zip and release the heat generated inside.


Weight is an essential factor that needs to be considered when thermal underwear is the product on auction.

Heavyweight apparel will restrict your movement and hinder your activities. In contrast, a lightweight one may give your freedom of action but not appropriate warmth.

It creates a dilemma in every customer deciding which one to opt for. Listed below are the different weights of these and their benefits. Scan them carefully before making your purchase.

  1. Ultralightweight

If you are visiting or living in a place experiencing low temperatures ranging between 23 to 18 degrees, opting for this type is the smart choice. It can be worn daily and is excellent for the onset of winter.

  1. Lightweight

A place with soothing cool or moderately cold temperatures is suitable for wearing lightweight underwear. It can also be used daily, and your body heat is enough to give you an adequate amount of heat.

  1. Moderate weight

Places with moderate to cold temperatures experiencing light snowfall are the best weather to wear moderate weight underwear. They keep you warm and cozy without overheating.

  1. Heavyweight

If you are going for backcountry skiing or any other snowy place, you should always wear heavyweight underwear. These are meant to be worn in areas experiencing extreme cold weather that can freeze you.


  1. Is it mandatory to wear the product as a base layer?

You can wear the thermal underwear on your skin, but you can add a base layer beneath it. The basic function of the product is to provide warmth, so a base layer will increase the comfort and will add an extra layer of protection.

  1. What is the difference between the high tech variant and the regular variant?

The high tech variant is made of synthetic fabrics that enhance the temperature retention properties of the product. This variant has a good moisture repellent feature and provides an adequate amount of warmth and insulation against the cold temperature. It is light in weight and does not restrict your movement, unlike the regular ones.

  1. Does the product cause itching?

If the thermal underwear is made of low-quality wool, then it can cause redness and itching. There are many grades of wool. The texture and quality make all the difference.

The shorter fiber length and coarse wool will cause more itching and redness and vice-versa. So, check the quality carefully before selecting an option for yourself.

  1. How to wash the product properly?

You can wash the product by hand or in a machine. For wool and cotton, use cold water and air dry it. If the product is made of silk, then don't wash the product in the machine. However, you can air dry it in the machine. Never use strong chemicals to wash the product. It can damage the quality and fabric of the underwear.

Final Verdict

With all this information at your disposal, all you need is to select an elite product. Here in this guide, we have laid out all the critical pointers that will aid you in sorting out the best option.

The thermal underwear presents a simple yet effective way to keep your body warm. Invest your money in the right option and enjoy the chilly weather with proper insulation. / - © Copyright 2020