What Is Down Fill Power? A Guide to Down Jacket Warmth
How down fill ratings work and how they can help you choose the right down jacket for your needs.
Down Fill Power Explained for Jackets and Insulated Outerwear
You’ll often see the term “down fill power” when choosing a down garment. This number measures the insulating efficiency of the down used inside a garment. Let’s talk fill power in more detail, including the fill power meaning, how down fill ratings work and how this information can help you choose the right down jacket, sweater or gilet for your needs.
What Is Down and How Is It Used in Jackets and Outerwear?
When it comes to cold and dry conditions, nothing beats nature’s lightest, most packable insulation: down. It traps warmth while being lightweight, and it’s compressible for packing. But what exactly is “down” in jackets and outerwear? Down filling for jackets is made from the soft clusters under the plumage of geese, waterfowl or ducks. These soft, light and fluffy plumes help insulate against heat loss and are different from the protective outer feathers that have quills and help birds fly.
At Patagonia, we use recycled down insulation in many of our down garments. The 100% recycled down we use is either 600- or 700-fill-power that’s a mix of duck and goose down and waterfowl feathers reclaimed from down products like blankets, cushions, duvets, bedding and other used items. It helps us save useful material from going straight to the landfill.
When a higher fill power is required for the technical performance needs of a garment, we use virgin down certified to the Responsible Down Standard by Control Union. Learn more about recycled down and the Responsible Down Standard for virgin down.
What Does Down Fill Power Mean?
Down fill power or “fill power” indicates the volume and fluffiness of the down inside a garment versus “fill weight,” which measures the actual quantity or weight of down filling used. Higher down fill power in a garment means the down provides a better warmth-to-weight ratio, thanks to fluffier down clusters that don’t require adding extra weight or bulk to insulate the garment better.
Down Fill Power Ratings and Cuin: How to Read the Numbers
The fill power number indicates the amount of space one ounce of down takes up in cubic inches (cuin). Down fill power ratings typically span between 300-fill-power and 900-fill-power. The higher the down fill rating, the better the insulating efficiency of the down. Down garments with higher ratings (like 800- or 900-fill-power) require a lower fill weight or quantity of down to provide the same warmth. Generally, the 600-fill-power and 700-fill-power garments we make with recycled down are best for everyday use. 800-fill-power garments are made for technical outdoor sports where performance, weight and compressibility matter most for cold-weather layering.
Does Higher Fill Power Mean a Warmer Jacket?
Down fill power isn’t an exact measure of warmth, but a higher down fill rating means the down insulation can better trap in warm air, as fluffier down has higher garment “loft” (or insulating efficiency). There are other factors at play when it comes to garment warmth, like the materials used, the fill weight and distribution of down insulation, and the garment construction method.
