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Temperature ratings for jackets? No. Just… no.

Lately, we’ve been fielding the same question from many of our customers: “What temperature are these jackets rated for?” We’ve been asked so many times, in fact, that we thought it made sense to write an in-depth article explaining our answer. After all, the question is coming more and more frequently, and since we’re not going to publish temperature ratings it’s important for everyone to understand why.

I suppose the reason this question is being asked is the few manufacturers or retailers out there who are publishing ratings. I sympathize with why people want a number; when you’re shopping for a new jacket, it can be difficult to assess whether or not it will be perfect for your intended purpose, especially when shopping online. It would be so much easier if there was just a simple number to look at: it’s going to be 20 degrees, the jacket says 20 degrees, done deal.

Tagging jackets with an arbitrary number, though, doesn’t simplify the process; it does you, the customer, a disservice. This is why our customer service team asks questions about where you’re traveling to, what activities you like, whether you think you’re cold-natured or overheat easily. Those are all parts of the correct answer.

Let me be clear: anyone telling you the “temperature range” for a jacket is making it up.

Here is a brief overview of the variables we find create problems for rating apparel, and why we feel the concept is ill-founded. It’s by no means a comprehensive list; I’m sure you can think of more variables than what we’ve included here.

  • Wind. We’ll start with an obvious one. Let’s say it’s 30 degrees outside with no wind, and you’re wearing your favorite fleece jacket at a football game, and you’re perfectly comfortable. Nice! Perhaps, for the second half of the game, the temperature is still 30 degrees, but now there’s a steady 15mph wind cutting right through your jacket. The temperature didn’t change, and your jacket didn’t change, but suddenly you’re freezing to death! Wind is a major variable in the comfort level of a specific garment; it alone invalidates the general concept of temperature ratings for many pieces.
  • Humidity. While we are discussing environmental factors beyond the actual temperature, we need to mention humidity as well. 45 degrees and dry can feel pleasant in nothing but a t-shirt and a light jacket, but 45 degrees and high humidity — common in many places and especially along the coast in winter — might be absolutely bone-chilling. Humidity levels also have an effect on the thermal efficiency of goose down; as down accumulates moisture, it becomes less effective, a problem that can be exacerbated as sweat evaporates from your own body.
  • Activity level. This one seems obvious, but is often overlooked: what are you actually going to be doing while you’re wearing the jacket? Thermal layers for running look very different than thermal layers for hunting, even though both activities might take place in identical conditions because one user is generating far more body heat than the other. Just as doing jumping jacks or push-ups in cold weather can warm your body quickly, an activity that keeps you moving will require far less insulation than one that doesn’t.
  • What else you’re wearing. So, you’re probably not wearing a string bikini underneath your new coat. That’s smart. What’s under there, though? Are you wearing a merino base layer, or just a cotton t-shirt? Are you wearing it outside two other layers — check out our article on layering outdoor clothing — or pulling it on over a sleeveless dress? Are you wearing a hat? After all, you’re always wearing something else besides your jacket. Aren’t you?
  • Body type. Research has shown that people with less body fat are typically more cold-natured; they lack natural insulation, if you will, and can chill more easily. Surely, you’ve noticed that some people tend to feel cold more easily than others, and it may not even be related to their body type. How would a manufacturer possibly address this? Should a size “small” jacket carry a different temperature rating than the size “extra large” version of the exact same jacket, based on assumptions about the wearer’s body type? Furthermore, could a manufacturer (or retailer) even make that assumption?

While all of these factors swing the balance in their own way, think of the massive differences in a jacket’s suitable temperature range when you combine them. On a windy, damp, overcast 50-degree day where you’re fishing from the bank of a river, a particular jacket might not even come close to keeping you warm. But the same jacket might be overly warm on a dry, sunny hike with no wind when it’s 30 degrees out. The variables are too numerous, and affect the outcome too greatly, for jacket temperature ratings to be of value.

So we’re definitely not lobbying for jackets to come with a tag that says: “this jacket is great for 35-45 degrees, provided you wear a base layer with it and a wool hat, and there is no wind, and the humidity is below 50%, and your BMI is within the healthy range for your gender and age, and also you should probably try to keep moving around a bit.” We’re saying that’s ridiculous… because it’s ridiculous.

We’re saying the concept is so deeply flawed, it should go away entirely. Please.

Photo by Christopher Burns via Unsplash

Wait, you’re thinking, don’t sleeping bags come with a rating system? They absolutely do, but there are two major differences here. First, EN ratings for sleeping bags define the relevant variables very clearly; EN ratings are based on a sleeper wearing one layer of long underwear and a hat, laying on a 1″ thick insulating sleeping pad. For sleeping bags, some of our most problematic variables from the list above (like activity level) don’t even apply. Second, though, EN ratings were created to clean up the industry at a time when sleeping bags were simply badged with whatever temperature rating the manufacturer deemed relevant, which of course varied dramatically between vendors and made comparisons impossible. After all, it’s better to reference a rating system based on something than one based on nothing.

In place of a rating for jackets, there are some other numbers you can look at. Many times, our product pages will show the gram weight of the fabric (250 gm/2 is heavier than 160 gm/2). Fleece jackets referred to as “200 weight” are heavier than “100 weight” styles. The fill power rating for down jackets measures thermal efficiency, not how much insulation is being used, but some manufacturers will specify the fill weight for insulated pieces.

That said, though, there is no substitute for good customer service. Not sure which jacket to buy? ASK US. Our team is really, really good at this, knowledgeable about the variety of options and can personally discuss with you which styles will be appropriate for your intended purpose — and which may not.

5 thoughts on “Temperature ratings for jackets? No. Just… no.

  1. So, I’ve always wondered about this. I realize that giving a jacket a “temperature rating” ignores a lot of other factors that influence your thermal comfort. However, I think an empirically measured R-value (just like for the walls of your house) would be very useful when comparing different jackets, especially ones that use different materials. For example, fill-power ratings are great for comparing two down jackets, but don’t help much when you’re comparing a down to a fleece. ASHRAE uses a “clo” value to measure clothing insulation for HVAC design purposes, but I’ve never heard of outerwear manufacturers adopting anything like it.

    1. Joe, I think that’s a good idea and I think that’s eventually where the industry is going to end up — we already see R-value being used for sleeping pads, where the concept translates very well. If nothing else, it would give you an opportunity to say “this jacket has a higher value than that one.”

      The problem we (and I, personally) have with temperature ratings as they are used right now goes beyond a lack of standardization. Some retailers, and a few manufacturers, are just literally making numbers up. Saying “yeah, this is about right for 30 degrees F to 50 degrees” doesn’t make things easier for the customer by providing useful data, it does them a disservice by oversimplifying something that isn’t all that simple.

      Real data is coming, sometime in the future, just like with the Simon thermal system and EN ratings for sleeping bags. Measurement Technology NW, specifically, is doing some cool stuff. We’re just not there yet as an industry.

  2. I’m moving to Finland for five years. What jacket should I buy? I’ll need something that can keep me cozy in temperatures as low as 20-30 below 0 (in Celsius). Any recommendations?

    1. If you’re going out in -30 and you’re not going to be active you will probably need some winter gear. Inner wool and outer wool with a winter jacket and winter pants.

  3. […] Temperature ratings for jackets? No. Just… no. […]

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