Of Ducks and Geese – What are Down Jackets and Why are they Warm?

Are Down Jackets Warm and Other Things You Need to Know
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As soon as you realize that winter is coming, you know it is the season to search the internet or retail store for a down jacket. You instantly know that these tend to be expensive, but they look extremely comfortable and puffy. But what we all really want to know is: Are down jackets warm or can you just get away buying a wool coat at half its price to stay warm?

In a place where the weather is freezing cold, jackets are not just a fashion statement but are a means of survival. So, are the claims that down jackets do an excellent job at keeping you warm true? We decided to go deep into this and talk about what exactly down jackets are, what to look for in a good down jacket, and how are they capable of keeping you warm.

What Is a Down Jacket or other Down Product?

The warm and soft under feathers from a goose or a duck insulate our down jacket. The more mature the bird, the larger the feathers will be. Large feathers will result in a higher down fill power rating and a more excellent loft. We will define these terms later, but first, we have to talk about why we use down in the first place.


Down, without a doubt, is a brilliant insulator. But what is really the purpose of insulation?

Insulation is essential to trap the heat coming out from our bodies and also to prevent it from escaping into the cold weather. This is basically a principle of thermodynamics wherein heat will move from a hotter location to a colder location so that it can achieve equilibrium.

In simpler words, the normal heat our bodies produce always moves out into the air that is around us. Having insulation means there will be a barrier between your body and the air outside. This, in turn, will retain the heat and will reflect back to you.

During production, down forms into clusters. Down comforters, pillows, jackets, sleeping bags, all use these clusters of down.

Every one of these clusters consists of thousands of tiny air pockets which can trap the warm air and retain its heat. This will ultimately help in keeping you warm even in the coldest of weathers.

The down fill of a down jacket will either be duck down, goose down, or a combination of both. Goose down is warmer and lighter than duck down. However, goose down is quite expensive, while duck down jackets or a combination of the two is still an effective yet accessibly priced option.

Fill Power

Fill power will measure the loft of a down product. This is essentially the measurement of the down’s quality. The maximum loft will occur when the clusters in the down are expanded at its fullest.

The fill power rating value gets calculated by measuring the number of cubic inches and is created in an ounce of down when it is at its maximum loft. For example, when the down fill rating is at 600, it basically means that 600 cubic inches are covered by an ounce of down. This is a process wherein the down is out into a Plexiglass cylinder and is compressed slightly with some weight.

It is vital to keep in mind that the fill power gets measured a bit differently in the USA as compared to Europe since there are different types of cylinders used. In the USA, this cylinder comes with a diameter of about 241mm and weighs approximately 68.3 grams. In Europe, this cylinder is larger measuring at 289mm and weighing about 94.25 grams.

Fill power rating typically ranges between 300 and 900, but can go beyond. You will find that several down products will have an average rating of roughly 400 to 500.

They are considered to be average to low-quality down products. They are also typically made from only duck down or a combination of immature goose and duck down, which means the clusters are smaller.

With that in mind, when you purchase a down jacket, it is essential that you look for one that has a fill rating of a minimum of 550. A jacket with this rating will keep you warm as well as comfortable.

Fill Weight

As stated earlier, fill power is the measure of the down’s volume. Fill weight, on the other hand, is the measure of the weight. Fill power basically rates the down’s quality, while the fill weight will state its quantity. So, if you have a jacket that has a down weight of about 12 ounces, it means that 12 ounces of the down material are used to manufacture it.

You will notice that several brands will proudly mention their apparel’s high fill power, but will often hide the weight of the fill. The fill weight is as important as the fill power since it helps in determining the apparel’s warmth, so this should not be overlooked.

To further state its importance, the fill weight is what determines how firm or how soft the apparel will be. It will also help in determining how well the product will compress.

A good down jacket must be folded with ease and stuffed into a suitcase without it taking too much space and being damaged. If the jacket is heavier, it will not compress easily; thus, damaging the jacket in the process.

Down to Feather Ratio

You may have often read about down to feather ratio. This basically calculates the percentage of the down to the percentage of the feather present. These numbers are typically shown as 90/10, 80/20, or 70/30.

The first number usually represents the percentage of the down, whereas the second number indicates the percentage of the feather. When you see apparel with a higher first number, it means that it will have better quality, but this is also quite expensive.

Down in itself is quite expensive as it offers better insulation in comparison to feather. So, a down jacket that comes with a 600 fill power along with 80/20 ratio of down to feather ratio means that it will offer more warmth in comparison to a jacket with the same fill power but a down to feather ratio of 70/30.

Why Is Down a Better Insulator Than Feathers?

Down is plucked from underneath the feather. Since these feathers are on the outside, they are what allow the duck or the goose to fly, float, and stay dry. Down is significantly firmer and also has quilts which act almost like a stem; in fact, getting poked by it will hurt you.

Feathers are not a bad option either. But since they tend to be harder, they are often used for more durable products such as seat cushions.

If the aim is to provide yourself with warmth in cold weather, then stick to using down duvets, jackets, and sleeping bags.

Are Down Jackets Warm?

Coming to the most crucial question “Are down jackets warm?”, yes, down jackets are indeed warm. But when you are looking to buy a down jacket, what should you give more importance to? The weight of the down or the fill power?

If you are looking for a down jacket with a primary purpose to keep you warm, then it is essential that you consider both these factors. Let us give you some examples which will help in illustrating how the down weight and the fill power work together.

  • A down jacket with 10 ounces of down along with a 500 fill power will be warmer than a jacket with only five ounces of down but a fill power of 800.
  • With the ratio of the down to feather and the down weight being equal, a 500 fill power jacket will not be warmer than a jacket with an 800 fill power.
  • A 500 fill power jacket will require more down in comparison to an 800 fill power jacket in order to provide you with similar warmth.

Again, it is quite common to find several brands only stating the down jacket’s fill power and not the amount of down used. This is because an 800 fill power jacket will weigh lesser than a jacket with 500 fill while providing you with the same warmth.

This is exactly why you will notice that performance athletes such as climbers, skiers, and hikers use down jackets with higher fill power as they are much lighter in weight, providing them with more mobility and warmth.

What About Clo Value?

Making sense of the whole relationship between the down weight, fill power, and the down to feather ratio can be extremely confusing. Today several companies use the Clo value.

The Clo value was invented in 1941. It measures the insulation value of the clothing that is necessary to maintain the comfort of the person sitting at rest at room temperature with humidity levels less than 50%. In simpler words, the Clo value is measuring how warm apparel is at a certain temperature and humidity level.

It goes without saying that a higher Clo value translates to the product offering more warmth.

So, for instance, a jacket with a fill power of:

  • 550 plus an ounce of down gives a Clo value of roughly 0.7
  • 625 plus an ounce of down gives a Clo value of roughly 0.92
  • 800 plus an ounce of down gives a Clo value of roughly 1.68

To give you a reference, the Clo value of a naked body is zero. A person needs a Clo value of one at room temperature. Assuming that winter temperatures range between –4 degrees to –40 degrees Fahrenheit, a person will require a down jacket with a Clo value of roughly four or higher.

What Are the Advantages and Disadvantages of Down Jackets?

Down jackets and other down products generally cost a lot more than their synthetic counterparts. However, when you ask anyone who has used down jackets in cold weathers, they will tell you that synthetic jackets are not remotely as effective as down jackets.

Down jackets are an ideal choice against cold weather. They will provide you with ample protection and will also last longer than synthetic jackets.

There are two important and quite obvious reasons why down jackets are a better buy. For starters, the heat retention and insulation down jackets possess is extremely impressive. You will also easily find authentic down jackets that are made mostly by reputed companies.

Additionally, they not only provide you with warmth, but they also look trendy and stylish. Nevertheless, you must ensure that the quality of the down jacket you buy is as high as possible.

That said, there is a downside to down jackets, too. Down jackets insulate less effectively when wet (which doesn’t make a lot of sense since ducks and geese spend a lot of time in the water). So, for you to be well protected from the cold weather, you must ensure that you do not get your jacket wet.

Thankfully, there is a solution to that. Nowadays, you will find quite a few down jacket manufacturers making jackets that are also water resistant. These down jackets typically have a 100% nylon shell and lining. So, if avoiding water is not an option, then we recommend you stick to using a down jacket crafted with water-resistant materials.


The direct answer to the question “Are down jackets warm?” is a yes. Down jackets will indeed keep you warm.

Down offers excellent insulation and also has brilliant heat retention. These features are what keep you warm.

Do note though that not all down jackets are the same. Each jacket is different in its own way. Even the kind of down can differ.

If your budget permits you then we recommend that you stick to using a down jacket made from goose feather. These are significantly better than duck feather and offer more warmth in cold weathers.

Also, make sure that the first or next time you buy a down jacket, consider the fill power, fill weight, and down to feather ratio so that you get the best down jacket for yourself.

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