Waterproofing and breathability go hand in hand. For a jacket to keep you dry, it must prevent moisture such as rain and snow from getting in, while simultaneously allowing excess body heat and sweat to escape to prevent you from getting wet from the inside. Some compromise between waterproofing and breathability is therefore needed. Waterproof garments are made from fabrics that are both waterproof and breathable. However, there are different variations as some fabrics are better at one than the other. Waterproof and breathable fabrics are given ratings based on their performance to carry out each function e.g. their ability to either keep water out or let sweat out. In this guide, we provide some examples to explain what waterproofing and breathability ratings mean and help you use them to choose the right waterproof and breathable clothing for your needs.

The waterproof rating attached to a waterproof garment is the result of a hydrostatic head test, where a column of water is placed onto the fabric and gradually increased until the water penetrates the material. The ratings are given in millimetres, so a higher rating means a jacket is more waterproof and can withstand a higher column of water (and thus water pressure) before leaking than a jacket with a lower rating. Below, we give some practical examples of what these waterproof ratings mean in real life.

Outerwear rated 3-5k is not considered fully waterproof, but is water-resistant enough to prevent moisture from making its way inside for a short period of time.

Able to deal comfortably with light rain, showers, and snow in colder conditions but unable to stand up to heavy rain for prolonged periods. This range is ideal for kids’ outerwear, waterproof clothing worn in the city and for outdoor activities such as short hikes, trail running and skiing in light snow.

Outerwear with this rating is designed to withstand medium to heavy rain and snow, making it especially suitable for outdoor activities like all-day hikes and skiing as well as travelling. This rating is able to stand up to most weather conditions, offering reliable protection without breaking the bank. However, if worn in heavy rain, when sitting on wet ground or worn with a backpack that adds pressure on the fabric for a prolonged period of time, some moisture may be forced through to the inside.

Ideal for multi-day trips, long walks and use in really wet and snowy conditions in the outdoors, this rating offers comprehensive protection over a long period of time, even when wearing a backpack or sitting down on the wet ground. Perfect for use in the mountains or for activities such as hiking, biking, skiing, and climbing, garments with this rating are a reliable and durable option that will stand up to all but the worst conditions.

Outerwear rated over 20k offers complete protection against the weather. Suitable for everything from multi-day trips with a heavy backpack to end of season skiing in wet snow conditions, garments with a 20k+ rating are among the most technical options out there. Ideal for trekkers, travellers, skiers, and more, these products may be slightly more expensive but they offer the most technical, reliable, and durable waterproof protection you can find.