What is Synthetic Down? Is it Any Good?

Last Updated on 29/12/2022

What is Synthetic Down?

This guide explains what synthetic down is and why you might use it vs. natural down for insulation. You will learn how synthetic down is made, the different types of synthetic down, and the products they are used in.

What is Synthetic Down?

Synthetic down is a man-made insulation made to mimic the qualities of natural Goose or Duck down. It is typically made from polyester fibers that undergo a process called melt spinning, but more on that further down. Synthetic down is ideal for outdoor gear like sleeping bags and jackets that benefit from having a high loft for maximum warmth and low weight and pack size.

Why is it called synthetic down? Natural down has such an unbeatable reputation in regard to jacket and sleeping bag insulation that a clever marketing team decided to call their new insulation material synthetic down. That isn’t the whole story, though, and the synthetic down insulation used today replicates the structure of feathers very closely.

Is Synthetic Down as Warm as Real Down?

In terms of warmth-to-weight ratio, synthetic down is not as effective as natural down. Natural down is warmer and lighter than synthetic down. Even at the low fill power of 650+ FP, synthetic down is still not as warm.

There are some other factors to consider, though. Like if the insulation gets wet or if the down has been hydrophobically treated. To fully get your head around this, you have to take certain variables into account…

First, I will start by saying there are multiple companies creating products that they may classify as synthetic down. Patagonia has its own PlumaFill insulation. Arcteryx uses Coreloft insulation, many brands use Primaloft, and there are many others out there as well as many others being developed right now.

The only time synthetic down is warmer than natural down is if they both get wet. Natural down will lose a significant amount of loft (up to 90%) and insulation value when wet whereas synthetic down is hardly even affected.

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How Long Does Synthetic Down Last? 

As I have only been wearing synthetic down jackets for the past three or four years, I can only base my opinion on my experience so far. I would expect that synthetic down will last over a decade or two if well cared for by following the manufacturer’s guidelines. This means washing and drying as recommended on the label, repairing any damage as soon as possible, and storing it uncompressed.

My Patagonia Micro Puff jacket, which I wear almost every day to walk the dog, is still going strong, and so long as I don’t damage the shell, I expect it to last a very long time. Will it keep its loft better than a natural down jacket with comparable insulation filling? Time will tell.

I have seen that synthetic down loses around 5-15% of its loft after you pack it in your bag the first few times. But then it seems to stabilize and doesn’t change much after that. Even if it gets soaked or you run it through the wash, it never goes flat as a down jacket would. Synthetic insulation also tends to clump less when wet.

synthetic down fibers close up

Benefits of Synthetic Down Vs. Natural Down

What is synthetic down and does it have benefits? There are several advantages that synthetic down has over natural down for insulation in outdoor gear:

  • Water Resistant: The main benefit of synthetic down vs. natural down is that it will continue to insulate you even when wet. Natural down’s most significant disadvantage is that it is vulnerable to moisture, so this is a big reason to choose synthetic insulation over down.
  • Animal Friendly: Because synthetic down is made using raw materials like polyester, no ducks or geese will be harmed. This is more important for some people than others but if we can get to a point where synthetic insulation surpasses the capabilities of natural down, then I am positive everyone will be on board for the animal-friendly option.
  • Affordability: Synthetic down is cheaper than natural down, as it can be produced entirely by machines and doesn’t require as much labor. This helps make synthetic down sleeping bags and jackets more affordable than natural down products which can get very expensive.
  • Hypoallergenic: Synthetic down is made from controlled materials and does not contain proteins, fibers, or dust that can cause allergies, making it a good choice for those who are sensitive.
  • Durability: Synthetic down is often more durable than natural down and can maintain its insulation properties even when wet. Again I have no proof of this, but I expect synthetic down to last longer than natural down from my experience so far.
  • Easy to Care For: Unlike down, which clumps after washing, synthetic down can be washed and dried with relative ease and without the same issues. This means you can keep it clean as well as stay warm.

The Disadvantage of Synthetic Down Vs. Natural Down

There is only one downside to synthetic down vs natural down that I can think of although I will add more if I can think of any:

  • Worse Warmth-to-Weight Ratio: Natural down is still the king of insulation for sleeping bags, jackets, vests, pants, and slippers. It packs down smaller, lofts up bigger, weighs less, and keeps you warmer than synthetic down. I do believe there will come a time when this switches as more advanced fibers evolve but for now, synthetic down has to stand back in awe when it is compared to natural down when weighed side by side.

synthetic down insulation

How Are Synthetic Down Fibers Created?

The fibers that we call synthetic down are created using a process called melt spinning. Synthetic materials like polyester are melted and then forced through a small opening called a spinneret. Once extruded through the spinneret, the melted fibers are exposed to air or water to cool them into high-loft strands that can then be used as insulation.

The exact process for making the strands of synthetic fibers imitate down is kept secret; however, I believe it is done using a combination of processes to starting with the blend of raw materials, the temperature they are heated in, the size of the holes on the spinneret, and the processes used to rapidly cool the melted materials into fibers.

Once the strands of synthetic down fibers have been created, they are then formed into a lofted structure that mimics down. This creates random patterns and shapes that allow the insulation to stay lofted and woven together without ever becoming flattened over time.

What is Synthetic Down Used For?

Synthetic down is mostly used for outdoor clothing and sleeping bags but it is also used in pillows, comforters, and campervan insulation products. The most common products are jackets, vests, pants, gloves, and on certain types of cold-weather boots as insulation.

When you are at risk of getting wet and also need to stay as lightweight and warm as possible, synthetic down is the more reliable option than natural down. 

Is Synthetic Down Waterproof?

Synthetic down is naturally moisture-resistant and does not absorb any water. The main benefit of synthetic down vs real down is that it continues to insulate and keep you warm even if you get soaked. Many synthetic down jackets are hydrophobically treated just like down sleeping bags which helps synthetic down insulation work even better.

That doesn’t mean that a synthetic down jacket won’t feel wet or allow moisture to soak through. It just means that the insulation doesn’t hold onto water.


We hope that after reading this guide you will be able to answer the question what is synthetic down?

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This article has been written and/or edited by Andrew N. 20+ years of hiking, mountaineering, and camping experience, with access to all the latest outdoor gear.

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