The short version: A good down jacket comes down to four things: fill power (600–700 is plenty for city winters), how much down is inside, the down-to-feather ratio on the label, and how the chambers are stitched. Fill power alone does not tell you how warm a coat is — and the number is not comparable across testing systems.
Puffers now span every price tier, from fast-fashion versions to designer ones. Max Mara Fashion Group’s new M-M For Mondays and More line, launched in more than 50 countries, lists a cropped puffer in coated jersey at €298, according to FashionUnited. At the top of the outdoor market, technical down jackets advertise 800- or 900-fill. The labels look similar. What is inside is not.
This guide explains what the numbers on a down jacket mean, which ones matter for everyday wear, and how to check a jacket in the shop — or secondhand — before you pay for it.
What does fill power actually measure?
Fill power measures how much space a fixed weight of down takes up, not how much down is in the jacket. Patagonia’s guide defines it as the volume in cubic inches that one ounce of down occupies: down that fills 650 cubic inches per ounce is 650-fill-power down. The fluffier the clusters, the more air they trap for their weight.
OutdoorGearLab puts it in kitchen terms: one ounce of 600-fill down lofts enough to fill about six two-litre bottles; one ounce of 900-fill fills about nine. Ratings typically run from about 300 to 900, according to Patagonia.
Higher fill power buys you warmth for less weight and a jacket that packs smaller. It does not automatically buy you a warmer jacket. That depends on how much down there is.
What is a good fill power for a winter jacket?
For walking around a city in winter, 600 to 700 is enough. Patagonia describes its 600- and 700-fill jackets as the ones for everyday use, and reserves 800-fill for technical outdoor sports where weight and packability matter most.
Paying for 800 or 900 makes sense if you carry the jacket in a pack, climb or travel light. For a commute, a 650-fill jacket with generous fill weight will usually keep you warmer than a skinny 900-fill one — and cost less.
Why is fill weight as important as fill power?
Fill weight is the actual quantity of down in the jacket, and it decides how warm the garment is as much as fill power does. Patagonia is explicit that fill power is not an exact measure of warmth: fill weight, how the down is distributed and how the jacket is built all matter.
The numbers can be surprisingly small. OutdoorGearLab estimates that a lightweight jacket weighing around 9 ounces typically contains about 3 ounces of down; the rest is shell, lining and zips. Brands that are proud of their fill weight publish it, in grams or ounces. If a label gives you a fill power but no fill weight, you are being told half the story.
Are fill power numbers comparable between brands?
Not always, and this is the detail most shoppers never hear. IDFL, a down and feather testing laboratory, lists several measuring systems in use: the IDFB method, the European EN 12130 standard (measured in millimetres per 20 grams or cubic centimetres per gram), the old US cylinder (cubic inches per ounce), Japan’s JIS and China’s GB/T and FZ/T standards.
The units can be roughly converted, but IDFL warns that conversions do not account for how the down was conditioned before testing — and conditioning changes the result. Its own comparison shows that some methods understate the fill power of compressed garments such as jackets, while steam conditioning, the only method currently approved by the IDFB, gives the most consistent reading. In practice: compare fill power between jackets from the same brand, and treat cross-brand comparisons as approximate.
What does 90/10 or 80/20 mean on the label?
The ratio is the share of down clusters to feathers. Down is the soft, quill-less clusters beneath a bird’s outer plumage; feathers have quills and do a different job — Patagonia notes they help birds fly. The British outdoor brand Rab lists its goose down at 90:10, with a minimum of 90% down, and its duck down at 80:20, with no more than 20% feather.
The legal floor for calling something “down” is lower than most people assume. According to IDFL’s comparison of labelling standards, the European standard EN 12934 allows a product to be labelled “down” with a minimum of 60% down, as long as the actual down content is stated on the label. The US standard requires at least 75% for a “down product”. So the word “down” on a swing tag tells you little; the percentage tells you a great deal. Look for 80% or higher, and treat a jacket that hides the figure with suspicion.
This is the same discipline as reading a fibre composition label: the useful information is in the numbers, not the adjectives.
Does the stitching make a difference?
Yes — it decides where the cold gets in. Most jackets use sewn-through construction, where the outer shell is stitched straight to the lining to make the familiar puffy tubes. OutdoorGearLab notes it is cheaper, easier and lighter, but loft drops to zero along every seam, which creates cold lines.
Box-baffle construction adds fabric walls between shell and lining so the down can loft across the seam. It is more expensive and slower to make, and is usually reserved for the warmest jackets. Welded or bonded baffles fuse the layers instead of stitching them; they avoid needle holes, which helps against wind and water, but the bonded line is a little wider than a stitch.
In a shop, hold the jacket up to the light. Thin, bright lines along the seams are where your warmth will leak.
Is down or synthetic better?
Down is warmer for its weight; synthetic is better in the wet. OutdoorGearLab’s testing found that soaked down goes flat, can take days to dry and gives little warmth until it does, while synthetic insulation keeps most of its loft when wet and dries faster.
Hydrophobic down, treated with a water-repellent finish, narrows the gap. OutdoorGearLab found treated jackets lost little loft in shower tests, though some untreated jackets did nearly as well, and the treatment’s durability is uncertain. For rainy cities, a down jacket under a shell, or a synthetic jacket, is the sensible answer. For cold, dry winters, down wins.
How do you know the down was ethically sourced?
Look for the Responsible Down Standard. Textile Exchange describes the RDS as a third-party certification covering animal welfare and chain of custody, and it prohibits force-feeding and live-plucking of the birds. Certified brands can name their certifier: Rab, for example, publishes its Control Union certificate number.
Recycled down is the other route. Patagonia says its everyday jackets use 100% recycled down at 600 or 700 fill, recovered from used products, while its higher-fill garments use virgin down certified to the RDS.
How to check a down jacket in five minutes
One. Read the inside label. You want the down percentage (80% or more), the fill power and, ideally, the fill weight. A label that says only “down and feather”, with no percentage, leaves you guessing how much of the filling is feather.
Two. Squeeze and release. Compress a panel and let go. Good down springs back quickly and evenly. Slow, lumpy recovery suggests low fill power, high feather content or clumping.
Three. Feel for quills. Run your fingers over the panels. Sharp points poking through the fabric are feather quills, a sign of a higher feather share.
Four. Check the seams against the light. Look for gaps in loft along the stitching and for empty corners where down has shifted.
Five. Look at the shell and finish. A shell that already sheds a little down, lumpy chambers, flimsy zips and loose stitching at the cuffs are signs of a garment built to a price. The same instincts apply as when you judge a wool coat in the shop.
Where to buy one worth keeping
Secondhand is where down jackets are often the best value, because a well-made one can be inspected as easily as a new one. Apply the same five checks, and add one: smell it. A musty jacket has been stored damp. Vintage and estate sources often turn up well-made jackets from outdoor and luxury labels for a fraction of the new price.
Independent makers and smaller outdoor specialists are worth the search when they publish fill power, fill weight, down ratio and certification on the product page. Accessible-luxury brands sit in the middle; judge them on the label, not the logo. Selective mainstream luxury can be worth it for cut and shell fabric, provided the down specification holds up. Skip the mid-tier mass market entirely: it is where vague “down and feather” labels and sewn-through construction are sold at prices that imply something better.
Frequently asked questions
Is 600 fill power warm enough for winter?
For most city winters, yes, provided the jacket has enough down in it. Fill power describes quality, not quantity; a generously filled 600 jacket can be warmer than a thin 800 one.
Is goose down better than duck down?
The species matters less than the numbers on the label. Rab, for instance, lists its goose down at 90:10 and its duck down at 80:20, so in that range the goose jacket carries more down per gram. Compare the down percentage and fill power, not the bird.
Does a higher fill power mean a warmer jacket?
Not on its own. Higher fill power means more loft per gram, so a jacket can be lighter and pack smaller for the same warmth. Total warmth depends on fill weight and construction too.
What does “down and feather” mean on a label?
It means the filling is a mix, and without a percentage you cannot tell how much is feather. Under EN 12934 a product needs at least 60% down to be labelled “down”, with the real figure stated. A label that avoids giving a percentage is telling you something.
Can you get wet in a down jacket?
Light snow and drizzle are fine, especially with a water-repellent shell. Prolonged rain is not: soaked down loses most of its insulation until it dries. Wear a waterproof layer over it, or choose synthetic for wet climates.
Where this leaves you
A down jacket is one of the few winter purchases where the label tells you almost everything, if you know which lines to read. Look for the down percentage, the fill power and the fill weight; check the seams; and pay for the specification you will actually use. A well-specified 650-fill jacket, bought new from a maker who publishes the details or secondhand after five minutes’ inspection, is a better buy than a pricier jacket with a vague label.
The next move is yours.
Sources: IDFL: comparison of down labelling standards · IDFL: fill power conditioning methods · Textile Exchange: Responsible Down Standard · Patagonia: down fill power explained · OutdoorGearLab: down jacket buying advice
