Fill power measures the space (in cubic inches) an ounce of down creates when allowed to reach its maximum loft. The higher the fill power, the larger the down cluster (actual ratio of down in a down and feather fill). This translates to a lighter, fluffier and more insulated product. Down fills are typically rated on a scale from 550 to 800+, with 650 to 750 being high quality and 800 and higher being the best.
Another important detail relevant to down products is fill weight. Fill weight is down’s weight measure in ounces. Typically, the higher the fill weight, the heavier the product. However “heavy” doesn’t necessarily mean “hot”. For example a comforter with a high fill weight and a low fill power will feel heavy without being overly insulating. Ideal fill weights vary according to preference and climate.
At Standard Fiber, fill power is first tested immediately after the down is washed, dried and sorted. This represents the “original” fill power which is used for all labels, advertising and marketing claims. Occasionally subsequent measurements will drop as a result of compression, shipping, and storage of the finished product. However, consumer use can often return fill power to its original value.