What is Thermal Clothing: A Complete Guide

what is thermal clothing explained

When it comes to winter wear, there are a lot of categories and subcategories of woolen clothing that might come off as confusing or even overwhelming for some people. But winter wear is very simple, even humorous. Let’s begin by discussing exactly what thermal wear is.

The word ‘thermal’ means heat. Thermal wear is also known as ‘long underwear’ or thermal underwear because of its appearance which is of elongated underwear that fits the entire body. There are plenty of reasons why wearing thermals is important in winter. For that, let’s start by understanding ‘What is thermal clothing exactly ?’

What is Thermal Clothing?

Thermal wear is usually made from cotton polyester. It comes in a fabric that has a ‘honeycomb weave’(a name appealing to its actual appearance). Thermals, when used as the innermost layer, perform a key function. 

Apart from not letting any chilly winds enter, thermals make sure that the body heat remains trapped and doesn’t escape. Further, the subcategorization of this fabric depends upon the kind of material that goes in its making. 

The polyester material is paired with wool or cotton. Sometimes, even Lycra is used. Depending on one’s resistance to heat, wear these thermals by pairing them up with outerwear and winter accessories.

What is Base Layer Clothing?

Base layers refer to the innermost layers of winter clothing. In cold weather conditions, base layers form the foundation for all the other layers. Many define them as ‘second skin’ thus referring to the many features they provide. This innermost layer soaks all the sweat and maintains the body temperature by not letting the body heat escape. It also prevents the extremely cold air from seeping in. 

Whenever you look for these online or in a physical store, understand that base layers stick to your skin for greater efficiency. That doesn’t mean that they should be uncomfortable or restrict your movements.

Kosha typically has three types of layers namely – base layers, mid-layers, and shell layers. According to the place of visit and your body resistance to cold, make an informed decision with what to opt for!

Base layer vs thermal clothing. Is there a difference?

While going through this blog, it might seem that thermal clothing and base layers mean the same and can be used interchangeably. However, that is not the case. 

The base layer you choose to wear can or cannot be made of thermal material. Both thermals and base layers are available in various fabrics. For a simpler explanation, it can be said that thermals are a type of base layer. In addition to this; both thermals and base layers are made with different purposes in mind.

Merino Wool Bamboo Blend Thermal Top

Merino Wool Bamboo Blend Thermal Top – base layer

Kosha’s base layers are made of thermal fabric. They are moisture-wicking (they absorb the sweat to keep your body warm). These thermal base layers are also temperature regulating which means that they respond to the change in body temperature and that the heat generated increases to the falling temperature.

What are the types of Thermal Clothing?

Thermal wear comes in different forms according to its utility. There can be thermal bottoms, thermal tops, and even thermal accessories to choose from. 

Kosha’s thermal base layers are as stylish as they are effective (if not more).In many cases, thermal clothing is worn under regular clothing. This step can be skipped when it comes to Kosha’s thermal base layers.

Initially, Kosha made its base layers solely with merino wool because it is the softest kind of base layer material. However, the customers complained as there was itchiness felt due to the material. Kosha, therefore, reinvented this product. Made with the combination of merino wool and bamboo, Kosha’s thermal base layers are made for your optimum comfort and warmth!

Base Layer & Thermal Clothing Tops

Kosha’s base layer thermal wear comes as half-sleeve and full-sleeved tees. Being light in weight they are highly compressible. These are available for both men and women. They are anti-bacterial, moisture-wicking, durable and so chic that they can be carried off directly in breezy winters!

what is thermal clothing explained

You can check out Kosha’s thermal base layer tops for men here

You can check out Kosha’s thermal base layer tops for women here

Base Layer & Thermal Clothing Bottoms

Material like denim, jeans, or even cotton is not suitable for extremely cold winters. While visiting a place that often experiences snow, make sure that the material used is waterproof, snowproof, and windproof. 

If the trip includes snow sports for the adventure junkies, it is also essential that the kind of clothes worn are compatible with these winter activities. Snowsports like skiing, snow hikes, etc need breathable material that allows free flow of movements.

Kosha’s thermal bottoms are just that! Made with merino wool and bamboo, these soft and warm pants make sure they match their purpose. They are also called thermal leggings. In case of extremely low temperatures, wear these underneath your regular clothes!

You can check out Kosha’s thermal base layer bottoms for men here

You can check out Kosha’s thermal base layer bottoms for women here


Accessories play a very important role when it comes to achieving peak warmth in cold weather. Winter accessories like gloves, mittens, beanies, caps, socks, scarves, mufflers, or even monkey caps when it comes to kids, are worth more than just their aesthetic value. 

All weather merino wool accessories

All weather merino wool accessories

These accessories make sure that the areas of the body that are usually exposed to cold climate, are covered and insulated. As snowy winters make the hands go numb, Kosha’s merino wool gloves impart great warmth while also providing the much-needed grip.

You can check out Kosha’s winter gloves for men here

You can check out Kosha’s winter gloves for women here

You can check out Kosha’s winter scarves for women here

What is Kosha Thermal Clothing made of?

Kosha’s thermal wear is made of merino wool, bamboo, and elastane. They are available in full-sleeved, half-sleeved t-shirts, thermal pants, thermal accessories, and more. The thermal tees can be used as actual T-shirts for casual winter outings.

Kosha’s range of thermal wear collection has additional features- It is soft on the skin with antibacterial properties. Being durable, it has anti-odour traits and is also moisture-wicking.

Do thermal clothes really work?

As mentioned in the introduction, thermal means ‘heat’. This is also why providing maximum insulation is the key feature of thermal winter apparel. Thermals are usually body-hugging for additional warmth. 

Best Thermal Wear India

Best Thermal and woollen wear

When worn as base layers, the material is such that it sticks to your skin thus leaving no space for chilly winds to enter. Thermal base layers also maintain the heat by not letting your natural body’s warmth escape. This is typically done as thermals tend to soak in your sweat.

All of these features make these the best choice when it comes to winter clothing. However, there is only so much that these can do. In places with very low temperatures pair these with appropriate outerwear depending upon your resistance to cold.

Read: The Best Thermal Wear in India

When should thermal clothing be worn? 

Based on the purpose and time of visit, how to put thermal wear to use must be decided. In places with pleasant winters, the thermals can be worn on their own. In regions of extreme cold, thermal wear should be paired with insulating outerwear like parkas, puffer jackets, sweaters, etc. 

Kosha’s thermal wear can be used in a temperature range of 15 degrees Celsius to 10 degrees celsius without any additional layers. When paired with more layers, this thermal wear can be used for temperatures reaching as low as -20 degrees celsius. 

Stylish Pullover for your best Thermal Wear

Stylish Pullover

The choice of which thermal wear to be used also differs according to the season and intention of the visit. If one visits Iceland in December for adventurous purposes, the type of thermal carried should be full-sleeved and it should be used as a base layer whereas Mumbai’s December can have the thermal base layer being used directly as a Tee!

Kosha’s thermal wear is super stylish, it also allows plenty of free flow of movements making it a suitable choice for any occasion. Wear these for taking a stroll across a park, or maybe with outerwear during a ski trek or a snow hike! 

For any queries related to wearing thermals, base layers, or winter wear in general, visit Kosha’s store and get a free consultation! While you’re at it, check out Kosha’s website for the wide range of thermals and base layers!

You can find the website here!

This blog article is written by Kosha Team Member – Sanika Totade.



Our history goes all the way back to early 50s. Prrem and Aloo Vazirani – an accomplished couple who chased after their wanderlust bug. She was a doctor, he was a businessman, and both were filled with a desire to explore the world.