All About Down Filling: Everything You Need to Know

What Is Down Filling Made Of?

Down filling is made of clusters. A cluster is a small, soft node with thousands of fine filaments radiating out from it, and it has no quill shaft. Feathers, by contrast, are the larger flat structures with a visible central quill. In commercial terms a down filling is always a blend of clusters and feathers, and the blend is described by a ratio such as 90/10 or 80/20, where the first number is the cluster share and the second number is the feather share. That ratio, together with fill power, is the foundation of every insulation specification a buyer writes.

The direct answer to the most common search question is this: down fill is made of the under-feather clusters of waterfowl, cleaned and blended to a defined cluster-to-feather ratio. Nothing is added to make it warm, because the warmth comes from the structure of the cluster rather than from the fibre content.

The Three Parts of a Down Cluster

A cluster has a central point, a dense set of filaments, and a natural surface coating on each filament. The central point is what makes a cluster spring back after compression. The filaments are what trap air, and trapped air is the actual insulator. The surface coating is why down repels a small amount of moisture before it starts to lose loft. When you judge a filling, you are really judging how well those three parts survived washing and how much of the cluster structure is still intact.

Feathers Are Not Filler: What the Second Number Means

Feather content is often described as an impurity, which is misleading. A measured share of feather adds resilience, helps the filling recover after compression, and reduces cost. Too much feather, however, brings two problems. The first is reduced loft: feathers do not trap air the way clusters do. The second is poke-through, where quill tips work their way through the shell fabric and turn a clean surface into a prickly one. For most branded programmes, 90/10 or 80/20 keeps loft high while controlling cost.

Ratios Explained

Cluster Size Matters More Than the Species Label

Marketing tends to lead with species. Technically, cluster size does more work. Larger, more mature clusters fill a given volume with less material, which is exactly what a higher fill power number represents. A well-graded duck down can outperform a poorly graded goose down, and the test report will show it. When you compare quotations from different suppliers, compare the fill power and ratio first, and treat the species label as a secondary cue about supply and price rather than a guarantee of performance.

Down Filling Grades: Fill Power, Ratio and Species

Fill power is the volume that a fixed weight of down occupies after it has been lofted and allowed to settle. It is expressed in cubic inches per 30 grams, or in cubic centimetres per 30 grams depending on the lab, and it is the single most useful number when comparing two fillings at the same ratio.

How Fill Power Is Measured

A measured sample of conditioned down is placed in a graduated cylinder, a weighted plate is rested on top, and the volume is read after a defined settling period. The result is a number, not a percentage. Because the test depends on conditioning and on how the sample was handled, two suppliers can report different numbers for material from the same bale. That is why a buyer should ask for the test method alongside the figure, and should treat a claim without a method reference as an estimate.

The Fill Power Bands Buyers Actually Use

Duck Down vs Goose Down

Geese are larger birds and their clusters are generally larger, which is why goose down typically reaches the higher fill power bands. Ducks produce a much larger share of world supply, so duck down gives brands more stable allocation and a lower price at any given fill power grade. For the majority of commercial programmes the practical difference is allocation and cost rather than warmth, provided the graded specification is the same.

White Down vs Grey Down

Colour has no effect on warmth. White down is used when the shell fabric is light enough that dark clusters would show through. Grey down costs less and is the sensible choice under any opaque shell. If a supplier quotes a large premium for white down on a black shell jacket, that premium is not buying performance.

Where Down Filling Comes From and How It Is Sourced

Down is collected in regions with large waterfowl processing industries. The material is a by-product of the food chain rather than a material produced for its own sake, which is why the traceability chain runs from farm to slaughterhouse to collector to washing plant to garment factory.

Collection Methods

Acceptable commercial down comes from birds that have been processed for food, with the down collected after slaughter. Live-plucking and the harvesting of down from live birds is not acceptable in any programme that a European or North American retailer will approve, and it is the reason the Responsible Down Standard exists. Forced feeding practices, used in some foie gras supply chains, are also excluded by the standard.

The Traceability Chain

Traceability is not a single certificate at the end of the chain. It is a chain of custody: the farm is identified, the collection point is documented, the washing and processing plant is certified, and the garment factory records which bale went into which order. A buyer who only asks for one document usually discovers later that the document covers a trading company rather than the site that actually washed the fill.

What RDS-Certified Down Filling Actually Proves

RDS proves that the material in a defined transaction can be traced through a certified chain and that the material did not come from live-plucked or force-fed birds. It does not certify fill power and it does not certify cleanliness. Those are separate test results. Buyers who treat RDS as a quality mark rather than a welfare and traceability mark end up with the wrong expectations during inspection.

Supply Risks to Plan For

Down is an agricultural by-product, so allocation follows the poultry cycle rather than the apparel calendar. Two risks are worth building into your schedule. The first is seasonal availability of high fill power grades, which can push sampling dates for premium styles. The second is price movement between quotation and bulk, which is normally handled by confirming the price for a defined validity window. If you are upgrading from 550 to 700 fill power late in a development cycle, expect both the price and the allocation to move.

How Raw Down Becomes Filling

Raw down arrives with dust, broken quill, oil and odour, and every one of those has to come out before the material can be used in a garment that a consumer will wear against the body. Processing runs in a fixed sequence, and skipping a stage shows up later as odour, clumping or loft loss.

Typical processing lead time: 10 to 20 working days from raw down release to baled filling ready for production.

How Down Filling Is Tested

Four test families cover almost everything a buyer needs to know about a filling. Each answers a different question, and no single report replaces the others.

Composition and Ratio Test

A laboratory separates a sample by hand or by mechanical means and reports the share of clusters, feathers, broken quill and other material. This is the test that tells you whether an 80/20 claim is real. It is also the test most likely to differ from a supplier's own in-house figure, because hand separation depends on operator judgement.

Fill Power Test

The cylinder and weighted plate method described above. Ask for the settling time and conditioning used. A difference of 25 cubic inches between two reports can be a genuine grade difference or a difference in test handling, so compare reports only when the method matches.

Cleanliness Tests

Oxygen number and turbidity measure residual organic material and the clarity of a water extract, and together they predict odour and allergen risk. A low oxygen number and a clear extract mean the washing stage did its job. Odour is also assessed by smell after steaming, which is a human judgement and should therefore be recorded as a panel result rather than a single opinion.

Moisture Content

Filling that arrives with high moisture content will clump, will weigh more than the specification assumes, and will lose loft in storage. Moisture is checked before baling and again at goods-in at the garment factory if the buyer controls it.

Where Down Filling Fails Most Often

Fill Weight, Fill Ratio and Cost: The Numbers Buyers Should Control

Three numbers decide what your jacket feels like and what it costs: the fill power of the material, the fill weight in grams, and the ratio of down to feather. Buyers often negotiate the first and ignore the second and third, then wonder why two jackets with the same headline specification feel different.

Fill Weight Is a Design Decision, Not a Specification

Fill weight is how many grams of filling go into the garment. A lightweight packable style might run well under 100 grams, a city coat might sit in the 150 to 250 gram range, and a deep winter parka can exceed 300 grams. The right figure depends on the climate your customer lives in and on how much of the body the jacket covers, not on a competitor's label.

Cost Per Gram and Why Fill Power Changes It

Higher fill power material costs more per gram but achieves the same warmth with fewer grams. That trade-off is why a 700 fill power jacket can price competitively against a 550 fill power jacket of the same warmth. When you build a costing sheet, model the fill as a total cost rather than a rate: fill power times fill weight times unit price is what actually lands in the garment.

The Hidden Cost of Over-Specifying

Specifying 800 fill power for a jacket sold in a city with mild winters adds cost without adding perceived warmth. It also narrows your supply options, because high-grade material is allocated earlier in the season. Most brands are better served by a moderate fill power with a carefully chosen fill weight and a wind-resistant shell.

Recycled Down and Certified Supply

Recycled down, recovered from used bedding and garments and re-washed, is a legitimate option for brands with circularity goals. Expect a separate documentation trail, a slightly different cluster profile, and a shorter specification list than virgin down. Certified virgin supply and recycled supply should be quoted as separate options rather than treated as interchangeable, because their availability and price behave differently through the year.

Down Filling vs Synthetic Insulation

The comparison that matters is not which material is better, but which one suits the way your customer uses the jacket. Down wins on warmth per gram and packability. Synthetic wins when the jacket will be wet for long periods, and when the brand needs a documented animal-free position. A brand that sells the same silhouette into a wet coastal market and a dry continental market should consider two fillings rather than one.

How to Choose the Right Down Filling for Your Product

Choosing a filling is a three-way fit between climate, price point and compliance. Start with the climate the jacket is worn in, then set the price point, then confirm that the material you have chosen can be documented for the markets you sell into.

Match the Filling to the Climate

For a market with mild winters, a moderate fill power with a lower fill weight and a wind-resistant shell delivers comfort without excess. For deep cold, increase the fill weight first and the fill power second, because fill weight changes warmth faster than fill power does at a fixed silhouette.

Match the Filling to the Price Point

Match the Filling to Your Market

European and North American retail programmes almost always require traceability documentation for down. If your sales channel includes any retailer with a published animal welfare policy, treat RDS documentation as a launch requirement rather than an upgrade. Confirm it before sampling, because switching fill mid-development restarts testing.

MOQ, Sampling and Payment Terms for a Custom Down Programme

Terms should be confirmed in writing before design work starts. The table below shows the terms we work to, so that you can compare quotations on the same basis.

If your programme needs a specific fill power or a certified supply that must be booked early in the season, share the requirement before the sampling date so that material can be reserved. You can send your requirements with the silhouette, target market and quantity and we will come back with a filling specification and a costing.

Certifications and Documentation to Request

Down programmes attract more documentation requests than almost any other outerwear category, because both quality and welfare claims need evidence. Four documents cover the normal range of buyer questions.

Step by Step: How to Start a Down Filling Project

A down programme moves faster when the filling decision is made before sampling, not after. The sequence below reflects the order that avoids rework.

Typical total timeline: 6 to 9 weeks from confirmed brief to shipped bulk for a standard down programme.

Frequently Asked Questions About Down Filling