If you’ve ever purchased any heavy-duty outerwear, you’ll notice a number marked on the tag. That is a waterproof rating. But what do these numbers mean, and more importantly, why should you care?
Any avid hiker, skier, snowboarder, or outdoor sportsman understands the importance of high-quality protection from the elements. Unpredictable weather patterns can turn an outdoor excursion into a disaster — and quickly. Preparing yourself with waterproof and breathable fabrics keeps you safe and comfortable so that you can enjoy outdoor activities to the fullest.
We’ll dive deeper into the meaning behind fabric waterproof and breathability ratings so you can start preparing for your next outing.
Fabric Waterproof Ratings Breakdown
Waterproof ratings essentially determine how water resistant a piece of clothing is. The “mm/24 hours” marking refers to the amount (in millimeters) of rainfall the fabric can withstand in 24 hours. So the higher the waterproof rating of a material, the longer it can remain waterproof.
Typically, manufacturers will design outerwear with a protective membrane that prevents water from soaking into the jacket. However, different manufacturers and fabrics determine how waterproof the fabric is. To do so, we’ve listed the fabric waterproof rating ranges below, including the relative conditions they can withstand.
Waterproof Ratings
Let’s take a look at the waterproof ratings:
0 — 5,000mm
Conditions: Light rainfall or dry snow.
This rating translates to little or no water resistance. For the industry to deem a jacket “waterproof,” this is the minimum rating. It can withstand the occasional sprinkle, but for a short amount of time.
Also – biiiiig difference between waterproof and water resistant.
6,000mm — 9,000mm
Conditions: Light rainfall, moderate snow; light pressure.
Outwear in this range can handle average rainfall under light pressure, but only for a short period.
10,000mm — 15,000mm
Conditions: Moderate rainfall and snow; moderate pressure.
Ratings up to 15K can withstand most downpours as well as heavy snow for a short amount of time.
16,000mm — 19,000mm
Conditions: Heavy rainfall, wet snow; moderate to high pressure.
Jackets with this rating compose of thick shells for heavy, intense rain over a prolonged period.
20,000mm+
Conditions: Heavy rainfall, wet snow; very high pressure.
If you plan to be outside for a prolonged time, this is the rating you should look for. A jacket with a 20K and above rating can withstand all weather conditions.
What It Means For You
If you’re looking for outerwear to keep you dry during light showers, anything between a 0 and 5,000mm rating will keep you dry for a short time. But in the case of heavy rainfall or cold weather conditions, you’ll want to look for something between a 5K and 10K rating. This rating will ensure your body stays warm and dry for a more extended period.
Anything above a 10K waterproof rating is an ideal option for rain, wind, and snow. And the 15K+ waterproof rating will better suit high-energy activity in all sorts of weather conditions for more active outdoorsmen.
How are Fabric Waterproof Ratings Determined?
Waterproof ratings vary from manufacturer to manufacturer. It also depends on the garment. Each fabric producer uses different methods, but the standard remains the Hydrostatic Head test, where the fabric is pulled tight under a 1″ x 1″ sealed square tube of water. For 24 hours, the material undergoes close observation to determine how many milliliters of water the fabric can withstand before leaking through.
Some methods also include adding different amounts of pressure, like wind, to ascertain how the fabric will react to various weather conditions.
Since different labs conduct different tests, it’s hard to determine the rating’s accuracy. Even if they use the same methods of protocol, labs can still come up with different results. Most labs use other means to determine waterproof ratings — something to keep in mind the next time you go outerwear-shopping.
However, waterproof ratings are relatively accurate if you can find a reliable brand.
Fabric Breathability Ratings Breakdown
Similar to waterproof ratings, outerwear generally includes a rating determining the fabric’s breathability. The fabric’s breathability relates to its ability to let sweat (in the form of water vapor) escape. The higher the rating, the easier it is for your sweat to evaporate. So if you do a lot of running or hiking-related activities, you’ll want to look for fabric with a high breathability rating.
Expressed in grams (g), breathability ratings depict how much water vapor can pass through one square meter of fabric (m²) in 24 hours.
The most breathable fabrics that runners swear by include cotton, rayon, linen, polyester, and merino wool. Quick-drying, moisture-wicking materials are what you should look for when buying breathable outerwear. Below, we’ve listed the fabric’s breathability ratings, including the relative conditions they can withstand.
Breathability Ratings
Let’s take a deeper look at the ratings below.
5,000 – 10,000g/m²
Conditions: Light rain; leisure activity that doesn’t require breaking a sweat.
This rating is the minimum breathability grade. This rating is adequate for minimal activity or general outdoor use but will get humid quickly if worn for a prolonged period. If you plan on a walk around the neighborhood or light jaunt, a jacket with a 5K to 10K will be sufficient.
10,000 – 15,000g/m²
Conditions: Light rain and dry snow; moderate activity like medium-high-intensity hiking or climbing.
Jackets in this range are suited to more active use or travel, specifically skiing. If you plan on spending more time in your shell, look for jackets with this rating. However, manufacturers do not design outerwear with this rating for vigorous activity.
15,000 – 20,000g/m² +
Conditions: Moderate rain and snow; vigorous activity resulting in heavy perspiring for prolonged periods.
This rating is ideal for the adventurous crowd and provides you with the highest level of breathability for extended aerobic use. With this level of breathability, jackets are great for hiking, running, biking, backpacking, snowboarding, or skiing.
What It Means For You
If you don’t plan on exerting a lot of energy, a low breathability jacket will suffice. But if you plan on working up a lot of body heat, you’ll need to look for outerwear with higher breathability ratings.
For amateur hikers or runners, anything with a 5K to 10K breathability rate will work. An extended activity like running and climbing demands breathability of 10K to 15K. Anything above 15K is ideal for avid sportspeople.
How are Fabric Breathability Ratings Determined?
Like waterproof ratings, breathability ratings are subject to the labs they’re tested in. Since breathability ratings are measured and determined in labs (where there are controlled conditions), not all ratings are 100% accurate.
Most lab testing doesn’t reflect real-world weather conditions, like freezing outside temperatures with high relative humidity. Keep that in mind as you’re shopping around for the right outdoor gear.
Though there are various testing methods to determine breathability, Moisture Vapor Transmission Rate (MVTR) testing is most common. MVTR measures the amount of water vapor that moves through a square meter fabric over 24 hours.
However, not all labs conduct the same tests. Results may vary based on the lab environment, temperature, pressure, and humidity. There’s no standardized method for all brands.
Don’t let the numbers scare you into buying a jacket with a rating you don’t necessarily need. While breathability ratings are undoubtedly important, don’t be surprised if your jacket may not be as breathable as it boasts.
In most cases, however, it’s safe to say that higher ratings indicate higher breathability. Before diving right in, you may want to conduct your own research. Figure out which breathability rating you need based on what you’re going to use the item for.
How to Choose the Rating That’s Right for You
There are several factors to consider before buying waterproof gear. Depending on the conditions, activity, and personal preference, every person’s right waterproof jacket, pants, or other gear will vary.
Conditions
Your living conditions play a significant role. If you live in dry weather, low-moisture environment, a low waterproof and breathability rating should suit you just fine. On the other hand, if you’re a PNW native, having a couple of jackets with high waterproof ratings is important.
Extreme weather conditions demand hard-shell jackets so that you can stay safe and dry from heavy rainfall. Look for outerwear that also has increased waterproof capabilities, like multiple layers constructed with durable fabric.
Activity
Before choosing the rating that’s right for you, take into account your lifestyle. If you’re a high-energy person that loves jogging, hiking, and biking, you’ll need a high breathability rating. But if you’re more concerned about not getting wet, a higher waterproof rating and lower breathability rating may be better for you.
For people who are into high-aerobic activity, look for items that use lightweight and breathable materials. There’s nothing worse than hiking in hot, clammy gear. Look for softshell products that offer adequate water resistance, breathability, and optimal warmth.
Personal Preference
There’s also personal preference to consider, as well. Instead of diving right in and purchasing the first item on the rack, take the time to do a little digging beforehand.
Figure out what materials you like vs. what you don’t like. Of course, the most reliable brands demand a higher price; but if you’re willing to spend the money, it’s worth it.
The Last Drop
Overall, waterproof and breathability ratings are a little subjective based on the manufacturer, but should help guide you in the right direction for what outdoor gear is going to be best for you. For more on different types of waterproof rating systems, check out our guide on IP ratings.
