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5 Tips to Buying Thermal Underwear

August 16, 2019 3 min read

5 tips to buying thermal underwear

Thermal Underwear Fitting

thermal underwear for couple

Thermal Underwear works as a second layer to the skin. It provides insulation between your skin and the thermal layer. 

The fitting of the thermal should be dependant on the weather for example a loose fitting would be perfect for the warm weather conditions and a tight fit would be ideal in cold weather conditions as a tight fit would trap the heat which is generated by your body providing comfort and warmth. 

Poor fitting thermal underwear makes it difficult for you to wear layers on top making you feel discomfort.



1.Thermal Underwear Fabric

There are two things you need to look at when choosing the right fabric:- weight and material. 

There are four different forms of fabric weight:


Ultralightweight: This is suitable for cool weather conditions

Lightweight: This is suitable for moderate weather condition and perfect for aerobic sports. 

Midweight: This is suitable for cold weather conditions

Heavyweight: This is suitable for extremely cold weather conditions especially in snow making it perfect for winter sports. 


2.There are four different types of material:

Synthetic Thermal Underwear:Ideal for extremely cold weather condition. Synthetic Thermal Underwear is a recommended choice for Thermal Underwear as it combines the following materials Polyester, spandex, lycra, and nylon to absorb the correct amount of heat. 

Wool Thermal Underwear:Wool controls your body temperature and helps to provide good moisture management. 

Silk Thermal Underwear:Silk is a lightweight material. Silk provides a thin feel without adding too much weight which makes it perfect to wear for winter sports.  

Cotton Thermal Underwear:Cotton may be a cheaper option compared to other fabrics however it would not be a preferred choice for Thermal Underwears as it leaves you feeling cold and sweaty.


3.Thermal Underwear Function

Here are the main reasons to why you should buy thermal underwear

  • Warmth - Thermal Underwear regulates heat making you feel warm. The weight of the thermal decides how warm it will keep you. 
  • Flexibility - Depending on the material, the fabric should have the ability to stretch. Cotton does not meet this requirement, wool does have somestretching properties.
  • Loft - The more loft the fabric has the more likely it will keep your body heat, whilst offering the least amount of space and more flexibility.
  • Bacteria Resistance - Staying away from bacteria is vitual
  • Moisture Wicking - The main purpose for a Thermal underwear is to keep us warm and this is done by keeping the moisture away from the skin. 


4.Thermal Underwear Styleall in one thermal

A base layer can be anything from thermals t-shirts, long/shorts sleeve tops to briefs and long johns.

However there are two styles to Thermal Underwear: 

  • All In One Suit which consist of top and a bottom.
  • Two seperate pieces or a set which includes a top and a bottom.


5.Thermal Underwear Care Guidelines

Cotton:Cotton should be washed in cold water and requires a longer time for it to dry. 

Silk:It is best to wash silk thermal underwear by hand or use the correct option if using the washing machine

Wool:It is best to wash wool with cold water. 

Synthetic Fabrics:Easy to wash. It is fine to wash with warm water and dried using a dryer. 


At British Thermals we supply a wide range of thermal underwear to suit everyone's needs. See below to view our product range:

Mens Thermals 
Womens Thermals 
Boys Thermals 
Girls Thermals


Thermal underwear discount code

If you need any help ordering from us, please contact our support team who are always ready to help. They can be contacted by email at or by telephone on 0116 262 2661.