The breathability of a material refers to its ability to wick away body moisture generated by perspiration, thus ensuring optimal comfort during exercise. By choosing well-ventilated clothing, you allow moisture to escape more easily, preventing the build-up of sweat inside. This is especially key during intense activities, as it helps keep you dry and comfortable, even in demanding conditions.
Breathability is measured using the Thermal Evaporative Resistance (RET) coefficient. It measures the capacity of a fabric to stop water vapour getting out. The lower this resistance (i.e. the lower the coefficient), the more breathable the fabric!
(The test method is defined by the ISO 11092 standard).
Why is it important to wear breathable clothing during intense sports activities, such as hiking?
Quite simply because during an excessive warm-up, or longer intense physical activity, we sweat. Depending on what we're wearing and the environment we're in, our body releases around 0.06 litres of water per hour at rest. With light exertion, this quickly rises to 0.5 litres of water per hour. If the effort is intense, a litre or more... and that's where the breathability of a fabric comes into play! quick moisture wicking. A fabric with good breathability reduces the condensation of water vapour inside the garment. It therefore facilitates the wicking away of perspiration and keeps the body dry.
In fact, this perspiration turns into body moisture and our clothing quickly becomes wet. That’s why it’s essential to wear clothing that ensures good breathability in order to quickly wick away this body moisture, avoiding condensation and keeping your body as dry as possible.
In this guide, we explain all the criteria for making the right choices in terms of ventilated clothing.
The breathability index of a garment, measured by the Thermal Evaporative Resistance (RET) coefficient, indicates the ability of a fabric to wick away moisture generated by perspiration. The lower the index, the more ventilated the fabric is, which allows body moisture to be wicked away easily, keeping the body dry. Conversely, the higher the index, the more the fabric resists the wicking away of moisture, making the garment less ventilated. The breathability test is carried out according to Standard ISO 11092, guaranteeing a standardised evaluation of this property.
The RET score uses a numerical index:
- RET < 6: the fabric is extremely breathable, so you’ll be comfortable while doing your most intense physical activity.
- RET between 6 & 12: the material is very breathable, making it suitable for moderate physical activity.
- RET between 12 & 20: the fabric is moderately breathable, and therefore not particularly pleasant to wear during physical activity
- RET > 20: the fabric isn’t very breathable and therefore not suitable during even light physical activity.
- RET >40: the fabric is considered to be non-breathable.
You’ll find this information in the technical specifications of our product sheets, particularly on our range of Men’s and Women’s jackets. It’s particularly important to measure breathability on this product, because generally, the more waterproof a garment is, the less breathable it is (due to the material or coating used to protect against the rain). If you want good breathability, over and above the fabric it’s made from, you can also choose a product with zipped mechanical vents that you can use to regulate your temperature.
Please note: some brands may also use the MVTR index to measure breathability, which stands for "Moisture Vapour Transmission Resistance". This index measures the amount of water that a square metre of fabric lets through in 24 hours. The lower this index, the more breathable the fabric. For example, a garment with an MVTR of 5,000 will have poor breathability, whereas a garment with an MVTR of 30,000 is extremely breathable. However, this criteria is less widely used than the RET scale.
To make the most of the technical features of your clothing, you must also coordinate the different layers of clothing according to your expected level of physical activity.
It’s ideal to combine waterproofing and breathability criteria in a garment to guarantee maximum comfort while practising your activity.
The membrane (or coating) contains millions of microscopic pores per cm², large enough to let water vapour from perspiration escape during exercise, but small enough to prevent rain or moisture from passing through in the opposite direction.
The right balance between waterproofing and breathability is key in keeping you dry inside your clothing, especially when the outdoor conditions are wet and intense. By manufacturing technical fabrics that meet these two criteria, you benefit from long-term comfort, whether you’re in the rain or doing intense physical activity.
At Quechua, the breathability and waterproofing of our products are priorities at the heart of our developments. As we've seen, this is an essential element in guaranteeing you maximum comfort when hiking. Our teams as , well as a tester panel (made up of partners, ambassadors and customers) test products throughout their development until they go to market. Our products are tested in the laboratory and in the mountains in conditions you may encounter on your hikes. Based on these tests, we design hiking jackets that meet hikers’ needs, offering both water-resistance and comfort.
