Breathability Ratings Explained

When it comes to comfort in the outdoors, it's important to choose your outerwear with both waterproof and breathability in mind. An ideal jacket would be both highly waterproof and also quite breathable. But what do the breathability ratings mean and how are they measured? Keep reading because we'll explain how outdoor fabrics are tested for breathability and what those ratings mean.

What Are Breathability Ratings?


If you've been looking for a new jacket, you might have noticed that most manufactures will include the waterproof and breathability ratings on the tags. Have you ever wondered what the breathability ratings mean? We explain the breathabilty ratings in this video and also in the paragraphs below.



The breathabilty rating is measured in grams per square meter per day or g/m2/day. To measure this, they take a square meter of the fabric and stretch that over a container of water. Then they measure how much water is able to transfer through the fabric in a 24 hour period. The higher the number, the more breathable the fabric is.

Why Breathability Ratings Matter


While this test is hard to put into real life situations, it does give a good comparison between two jackets. If you are doing a light hike in cooler temperatures, you'll probably be happy with a jacket in the 5,000 to 10,000 g/m2/day range but if you are running hard and creating a lot of heat in humid weather, you'll be much happier in a jacket with 20,000 + g/m2/day.

Breathability Ratings

A breathable jacket will allow your excess body heat to escape which will allow you to regulate your body temperature. This will reduce the clammy and sweaty feeling that non-breathable jackets cause. A jacket with pit-zips or mesh sections in the high heat areas may help you compensate for poor breathability. I'd suggest you purchase the jacket with the highest breathability rating in your desired price range.

I hope you've found this information on how to choose the best jacket or piece of outerwear helpful. For more information, check out our article on waterproof ratings or visit the gear guide.
Andy Hawbaker
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Andy Hawbaker
Andy is a hiker, backpacker, snowboarder and outdoor fanatic. When he isn't exploring the Rocky Mountains, burning marshmallows or scratching his dog behind the ear, he shares his experiences here on the Sierra Trading Post Blog.
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