Breathability explained

In this short blog, we discuss the breathability of materials and the different methods that can measure it. You probably already have an idea of what is meant by the former, but we still recommend you read this blog. After all, for certain technical clothing, it's really important that you understand this concept well and know what to look out for to avoid expensive mispurchases.

Table of contents

• Breathability
• The MVTR measuring method
• The RET measuring method

Breathability

The breathability of clothes or shoes, for example, refers to the ability of the fabrics used to let air through and wick moisture away from the body. Properly breathable garments allow perspiration and excess heat to escape, keeping you dry and comfortable. Even during intense activities.

Although breathability certainly plays a big role in the bottom and middle layers of the 3-layer system as well, we mainly talk about this concept in relation to the top layer. This is because this very layer can be the major limitation to the breathability of your complete clothing outfit. How exactly is this? At first glance, the primary task of the upper layer seems to be to protect you mainly from wind and precipitation. In other words, from outside threats (external threats). However, if you are also active at the same time, all kinds of heat can accumulate from within your own body and you can then start to perspire heavily (internal threats). If this cannot escape because the top layer does not breathe sufficiently, you will still get wet. But from the inside. So you need a top layer that protects you from both external and internal threats. We are talking about a top layer that is not only wind- and waterproof, but also has good breathability. We discuss the technology that makes this possible in our blog on waterproof membranes.

But how do you find out how good a product's breathability is? With most products, you can tell from the materials used. Certain fabrics breathe better than others. Such fabrics are actually always used for under- and mid-layer clothing. However, this reduction method does not work as well for the top layer. To assess breathability then, you often have to rely on specific measuring methods.

The MVTR measuring method

There is no official industry standard for measuring the breathability of a garment or fabric. However, different tests do exist (which, incidentally, can also give different results). One of these tests is the MVTR method, where MVTR is an abbreviation for "Moisture Vapour Transmission Rate". This method measures how many grams of moisture/water vapour penetrate the fabric surface of one square metre within 24 hours. The results are therefore given in g/m²/24h. The higher the value, the more breathable the fabric. We interpret the test results as follows:

The RET measuring method

Another commonly used method of measuring breathability in textiles is the so-called RET method. RET stands for "Resistance to Evaporating Heat Transfer". So here the resistance is measured, instead of the permeability measured in the MVTR method. With the RET method, the lowest possible result is therefore desired. The results are displayed in m²/Pa/W, although many brands only display the number. So an RET of 10 instead of 10 m²/Pa/W. We interpret the results of the RET measurement method as follows:

Hopefully with this blog we have been able to make it clear to you, what exactly is meant by a product's breathability. By the way, there are many other terms used to describe the properties of a fabric. We name and explain these on our page about the various material characteristics. Knowing these will certainly help you make a better choice when it comes to outdoor clothing, shoes or equipment. If you still have some questions, you can of course always contact our customer service. We will be happy to help.