Ever wondered what all those numbers in descriptions of down jackets mean? They actually tell you a lot about the quality of insulation and warmth of a particular jacket, but only if you know how to read them.
There are a few different things brands will tell you about the insulation of their jackets – type of down, the fill power of down and the ratio of feather-down. I’m here to explain everything about those numbers, and hopefully help you learn how to spot the best down jacket!
The first thing you need to look for is whether a jacket is insulated with goose down or duck down. That is one of the most important things, since it also impacts fill power, amount of insulation and down-feather ratio.
Duck down is what you usually see in jackets, as it is pretty easy and cheap to produce. The vast majority of brands use duck down in their jackets, especially the more affordable ones. But it is also of lesser quality than goose down.
That is because clusters of goose down tend to be larger than clusters of duck down. That results in higher fill powers, better quality, durability and lighter clothing.
Let’s put it this way – say you have the same amount of clusters of goose and duck down. You would need more duck down, because the clusters are not as large and they cover smaller amounts of space. That also means that it’s more likely there will be holes in the insulation – empty space between the clusters, areas that are not covered with insulation. That’s what someone means when they say a jacket has cold spots.
Insulation is supposed to trap your body heat. When a jacket has cold spots, the heat escapes through them and you don’t feel as warm as you should.
The thing is, goose down is more expensive to produce, and so jackets that insulated with it are never cheap. So, it is not used as often.
However, there are instances in which duck down is actually the better option – high quality duck down obviously performs better than mediocre goose down.
Fill power is directly related with size of down clusters – that’s why goose down generates higher fill powers than duck down.
It measures the size of space one ounce of down is able to insulate, when it reaches maximum loft. Larger clusters are able to trap more air, and are better at retaining body heat.
Fill power can be identified by the number that accompanies it. That number usually ranges from 350 to 900, and it indicates how many cubic inches a single ounce of down occupies.
So, say you want to cover 700 cubic inches with down – you can do that with a single ounce of 700 fill power down, or two ounces of 350 fill power down. And in that case, the latter would actually be warmer, but I’ll tell you more about that a little later, when talking about how weight of insulation impacts warmth.
When you look at average down jackets you can buy today, you’ll notice that most of them are insulated with 550-650 fill power down. That’s kind of like the best middle ground – it’s high quality, has high loft, but not too expensive to produce.
Jackets that are insulated with 700-900 fill power down are usually warmer, but they are much harder to find. And these are usually jackets designed for some extreme weather conditions.
If you are looking to get a warm winter jacket, look for anything with 550 fill power and above. Anything lower than that won’t really be warm enough for sub-zero temperatures.
900 fill power goose down is the golden standard – as good as it can get. But not a lot of brands offer jackets with this insulation, and especially the cheaper ones.
North Face is one of the few that makes these jackets, but they tend to be really expensive. However, if you’re looking for the warmest jacket money can buy, that’s the number you should be searching for.
This is a very interesting thing that people often overlook. For one thing, many manufacturers won’t even tell you the amount of insulation in their jackets – they’ll usually tell you about fill power, sometimes about down/feather ration, but they often skip this one. That’s because it actually plays a really big role in keeping you warm.
Maybe you’ll see a jacket that’s insulated with 700 fill power down for $50. And that is too good to be true – what the manufacturer isn’t telling you is that there’s probably very little insulation in that jacket. Meaning that it is not completely insulated and it has cold spots, and you won’t actually be warm in it.
The heavier the amount of insulation, the warmer a jacket is. Say you have two jackets, one is insulated with 100 grams of 550 fill power down, and the other one with 60 grams of 700 fill power down. Which one is warmer?
The first one. Let’s just look at the numbers here – 100 grams is 3.5 ounces. That means that the down in the first jacket takes up 1925 cubic inches of space.
Now, what about the second jacket? 60 grams is 2.1 ounces, so the total amount of down is able to insulate 1470 cubic inches. And it turns out that the first jacket is actually significantly warmer than the second one – more insulation means less cold spots and higher warmth level.
So you see, it’s not just about the fill power. The actual weight of down in a jacket plays a huge part as well, and that’s one specification you should always be checking. If you are looking at a jacket in store, you should be able to find that info on the tags. If you’re looking at it online, you can always contact the brand and ask them directly.
However, keep in mind that jackets with more insulation are usually more expansive, especially if they are insulated with really high fill power down.
Down to feather ratio is the amount of down inside a jacket, versus the amount of feathers. The higher the number in favour of down, the warmer the jacket.
High quality jackets should have at least an 80-20 down-feather ratio, because down does a much better job at trapping air than feathers. Basically, feathers are like fluff – you know when you’re reading an article and most of it is fluff, and then the actual interesting information is only 30-40% of the article? That’s the feathers. The higher their amount, the lesser quality the jacket is.
90-10 ratio is as good as it gets, and that’s what you’ll see in high quality brands like North Face or Moncler. And most of the good brands will actually tell you the ratio of down-feather in one of their “about us” articles, because the ratio is the same in all of their jackets. If a manufacturer avoids telling you this in one of their jackets, then you can assume that it is lower than 80-20.
Which doesn’t mean the jacket is useless – I have several 70-30 jacket that are great for late fall and early winter. It all depends on the area you live in and how cold it gets there. In my experience, 70-30 jackets are great for temperatures that don’t drop below 4-5 degrees Celsius. But for anything colder, you will want more down in your jacket.
This is another thing people often overlook. A jacket can be insulated with 100 grams of down, but what if all of that insulation covers only its body? The sleeves and the hood won’t be nearly as warm as the rest of the jacket.
And that’s something not all manufacturers will tell you, and you will completely forget about it until you’re walking around the town and your arms start freezing.
A jacket that has 90 grams of down, but which is entirely insulated (including the sleeves and the hood), will be warmer that a jacket that has 120 grams of down but only in the body. That’s because your entire body will be warm and cozy, and your body heat will stay inside the jacket.
But if that is not the case, even if the jacket is insulated with 900 fill power down, you won’t be as warm – eventually, your arms will start to feel cold, and that is a feeling that can easily spread.
Some brands will tell you that these parts of their jackets are filled with down – Canada Goose is one of those, and the first one that comes to mind. You should always look for this info in the descriptions of the jackets. And if you’re not sure, don’t be afraid to ask questions – after all, you should know exactly what you are getting for your money.
So, let’s take everything I’ve told you about down insulation, and figure out how to find the perfect jacket. And it’s actually not as simple as “oh let’s just look for the highest fill power with the highest amount”. Being too warm is a real issue – one that can render your brand new, ridiculously expensive jacket useless.
You ned to consider how cold your area gets in the winter. If the temperatures are often below zero, then you should be looking for higher fill powers, and generally jackets that are heavily insulated. Canada Goose actually has a really helpful rating system for their jackets, as they tell you exactly the temperature range in which they are designed to be worn.
But if you live in areas where winters are milder, don’t get ahead of yourself and buy a super warm jacket – you’ll rarely wear it. If you want something you can wear every day, look for jacket with lower fill powers, or high fill power but lower amount of insulation.
That was a lot of information I just threw at you. So, let me sum it up:
I think that’s all. If you think I forgot anything or still have any questions about down fill rating, feel free to ask me in the comments!
Anna is the co-owner of expert world travel and can't wait to share her travel experience with the world. With over 54 countries under her belt she has a lot to write about! Including those insane encounters with black bears in Canada.