The Great Insulation Debate: Natural v. Synthetic Down

In Outdoor, Tech / Gear, Performance

If you want to stay warm in really cold conditions, one of the things you need to establish is whether to opt for garments made with natural down or synthetic insulation.  

In this article we get to grips with down terminology, examine the pros and cons of natural and synthetic down and name check a few brands that really know their stuff when it comes to insulation.

Quick Menu Navigation

  1. What is Natural Down Insulation?
  2. The Science Behind Down Insulated Garment Ratings
  3. What is Synthetic Down Insulation?
  4. What is Hybrid Insulation?
  5. Box Baffle versus Sewn Through Construction
  6. What is Natural Down Insulation Best For?
  7. What is Synthetic Down Insulation Best For?
  8. What are the Ethical and Environmental Concerns Surrounding Natural Down Insulation?
  9. What are the Ethical and Environmental Concerns Surrounding Synthetic Down Insulation?
  10. Which Brands Make the Best Natural Down Insulated Garments?
  11. Which Brands Make the Best Synthetic Down Insulated Garments?

Goose flying in mountainous winter landscape

What is Natural Down Insulation?

Down is the soft, fluffy plumage that sits beneath the feathers of ducks and geese. It is one of nature’s best insulators and works by trapping air to keep you warm. Goose down is generally considered to be the superior insulator, but duck down products are usually more affordable (and a premium duck down may be better than average goose down, so you can’t get too judgemental about it).

The Science Behind Down Insulated Garment Ratings

When you look at the label of a down filled garment you should see two ratings; the down-to-feather ratio and the fill power. The first rating is fairly self-explanatory; an 80:20 rating means 80% down and 20% feathers. As a general rule, the higher the percentage of down the warmer the garment will be. 

The fill power rating shows how effectively warmth is retained, and this is established by discovering how many cubic inches one ounce of down can loft after compression. This is tested in a laboratory by compressing an ounce of down under a weight in a glass cylinder. The down’s ability to bounce back (or ‘loft’) is calculated as the fill power.

A high fill power rating means that the down contains a greater number of air pockets and will have a greater warmth to weight ratio. If you invest in the best quality down you actually need less to provide the same amount of warmth than a lower quality down. This means that jackets with a higher fill power tend to be lighter and more compressible.

The following table gives you a rough idea of what fill power ratings mean:

Fill Power Rating

Warmth to Weight Ratio

400 - 450


500 – 600


650 – 700

Very Good

750 - 900



What is Synthetic Down Insulation?

Synthetic insulation is man-made equivalent of natural down and is created using polyfibres, which attempt to replicate the heat-holding properties of duck and goose down. Traditionally synthetic down has been the poor relation of naturally derived down, as it is heavier and loses heat more quickly. However, improvements in synthetic down technology mean that there is a very real possibility that it will soon be able to replicate the insulating properties of natural down, with (pardon the terrible pun) none of its down sides, such as its bulkiness, poor breathability and inability to retain heat in wet conditions. Primaloft, PolarTec and Plumtech are just some of the innovations in synthetic down technology that are giving natural down a run for its money.

What is Hybrid Insulation?

Some brands are getting technical and mixing down and synthetic insulation in their garments. This can take the form of, for example, down insulated front and back sections and synthetic sides and sleeves, which can make the garment feel less bulky.

However, the real innovation lies in mixing down and synthetic fibres within the jacket, in an effort to create a balance that offers optimum warmth and moisture wicking properties. The ultimate aim of hybrid insulation is to maximise the desirable features of insulation technology (warmth, ease of movement, packability and moisture management) and minimise the 'flaws' inherent in a single material solution. The technology is still being perfected, but it could result in high-performance jackets that are available at a lower cost to the consumer.

Box Baffle versus Sewn Through Construction

Sewn Through

In sewn through garments the outer fabric is sewn to the inner lining to form chambers of down between the stitches. In sewn through construction, there is no down in the seams that border the chambers of down, which can result in cold spots. The stitching also compresses the down at the edges, preventing it from lofting to its full extent. Sewn threw garments are quicker, easier and cheaper to make than box baffle ones, so they are the most common type on the market. 

Box Baffle

In box baffle garments, each separate baffle has its own section of down, which maximises the loft and warmth of the down fill, which results in fewer cold spots. Garments made using this method are generally thicker and warmer than sewn through versions, but they tend to be more expensive, as they require extra material and are a more complex construction.

What is Natural Down Insulation Best For?

  • Extremely cold conditions
  • Dry cold climates
  • Pastimes where weight and compressability are important factors, such as alpine climbing

What is Synthetic Down Insulation Best For?

  • Wet and humid conditions
  • Times of physical exertion, when your body is consistently producing more heat and you won’t suffer as a result of synthetic down’s inferior heat retention. 

What are the Ethical and Environmental Concerns Surrounding Natural Down Insulation?

Much of the down that is used for clothing is a by-product of the meat industry, so by association there are ethical issues surrounding the sustainability of meat-eating in environmental terms. In addition, there are specific cruelty concerns around live plucking and force-feeding of the ducks and geese involved.

Whilst down will never be an option for vegans, there are some brands, such as Patagonia and North Face, which are working hard to eliminate cruelty from their supply chains. However, 80% of the world’s down comes from China, where animal rights are far lower and animal faming regulations far less rigorous than in America and Europe, so the majority of down insulated products are filled with down that cannot be guaranteed cruelty-free.

If you are committed to buying a natural down garment and want to ensure that the down used is ethically sourced, look for down that has been certified by the Responsible Down Standard. In order for down to be certified by the RDS, each link in the down supply chain has to be verified by a third party to ensure that every aspect of production adheres to the level of animal welfare set out by the Standard.

In terms of what happens at the end of an insulated jacket’s useful life, a down jacket is unlikely to be fully recyclable as there is little demand or infrastructure for down recycling (whereas synthetic alternatives such as PolarTec and Primaloft are fully recyclable). Whilst down is a natural product and will biodegrade without causing much environmental harm, it is worth noting that the majority of down jackets are made using synthetic materials, which can cause environmental harm once they have been discarded. 

What are the Ethical and Environmental Concerns Surrounding Synthetic Down Insulation?

The production of synthetic down can be energy intensive and there is the potential that its manufacture in poorly regulated factories could harm the operatives involved. Also, given that most synthetics are petroleum based, there is a detrimental environmental impact associated with their production and potentially in their disposal once the garment is worn out.

Given the huge strides that synthetic down is making in narrowing the performance gap with natural down, it is no wonder that companies involved in its production often keep the specifics of processes and materials as trade secrets. This is great for the industry and less good for the ethical consumer trying to make an informed purchase decision.

Having examined the ethical and environmental issues surrounding down and synthetic insulation, it seems that the most important thing you can do is ensure that you have done your research and bought the right product for your requirements (be that natural or synthetic down). After all, the most ethical purchase decision is to not to buy at all, so if you really do need an insulated jacket, make sure it is good quality and fit for purpose, so that with the right care and attention, it will last for years before it needs to be replaced. 

Which Brands Make the Best Natural Down Insulated Garments?

Woman in red down jacket on hill

There is no one-brand-fits all outright winner when it comes to down insulated garments. Someone looking for a warm winter jacket or gilet for general cold weather use has different priorities to someone looking for an ultra-packable, super warm layer for serious alpine climbing. Having said that, there are some brands that know down insulation inside out and are doing it better and more ethically than most of their competitors. Here are some of the brands we favour when it comes to down insulation.

Patagonia ­– Committed to using premium quality down that meets the highest ethical standards, Patagonia can assure consumers that one hundred percent of all virgin down it sources is certified by NSF to meet the Advanced Global Traceable Down Standards (and so are their down suppliers). Their Down Sweater Jacket does well in reviews, scoring highly for weight and durability. It is also filled with hydrophobic down, so performs pretty well in wet conditions, whether you are wearing it for a winter trip to the shops or tackling a challenging mountain climb.

Arc’teryx – This Canadian mountaineering brand’s experience of the wilderness landscape on their doorstep means that they know what’s need to keep you warm in the most extreme conditions. Their Cerium LT Jacket was voted Best Down Jacket for 2021 by Outdoors Magic and, although it will set you back £320, its innovative design and quality craftsmanship make it a worthwhile investment for mountain adventurers.

Berghaus - This UK based outdoors brand often finds itself in rundowns of the best down insulated jackets. Its Tephra Stretch Reflect Down Jacket (pictured above) is filled with ethically sourced hydrophobic down, which means that is can continue to keep you warm, even in wet conditions. 

Which Brands Make the Best Synthetic Down Insulated Garments?

Funnily enough, many of the brands that make the best natural down garments also do a fantastic job of making synthetic down ones too (I guess they just know the science of keeping us warm, no matter what material is involved). Here are a few of the brands to watch when it comes to synthetic down innovation: 

Product images of the Patagonia Nano Puff jacket

Patagonia – If there is an outdoor brand that never rests on its laurels in terms of the performance and sustainability of its products its Patagonia. The most recent incarnation of their Nano Puff insulated jacket (pictured above) contains 100% recycled polyester insulation. It also features a lining and outer shell made from 100% recycled materials. It’s perfect for eco-conscious backpackers and cyclists looking for a portable, mid-weight insulated layer for their adventures.

The North Face – Named after the coldest side of a mountain, this well-known outdoor brand was actually established in San Francisco in the 1960s. It has since helped intrepid explorers conquer personal challenges in some of the most difficult conditions. The North Face teamed up with Primaloft to create Thermoball, a new synthetic alternative to down that mimics the clumping behaviour of down clusters in order to trap heat in small air pockets and retain warmth.

Their Eco Thermoball jacket is warm, packs down small and has the added advantage of being a bit of an eco hero as well. The insulation and the face fabric are both 100% recycled and it’s PFC free too. All this for a comparatively thrifty £160!

Haglöfs V Series Mimic Jacket

Haglöfs - This innovative Swedish brand is committed to creating high performance synthetic insulation that doesn’t skimp on eco-credentials either. Their Haglöfs V Series Mimic Jacket contains the award-winning material, graphene (more commonly used to strengthen the soles of high end trainers), which is mixed with Mimic Platinum synthetic down in order to maximise heat conduction throughout the jacket.

*All images used are the property of the brands they depict and permission to include them has been obtained by the author prior to publication.