What is “Fill Power” and how is it measured?
Down is measured by it’s fill power. This means if you take one ounce of down and compress it, when it’s released it will expand and fill so many cubic inches, hence the term fill power, or loft. The higher the fill power, the more warmth is trapped inside the comforter, so the warmer the comforter. Siberian down is considered the best down in the world because it has the highest loft and gives the comforter a soft, lofty look. Comforters with lesser quality down will not have the loft or fill power and will not be as warm given the same amount of fill. For example, if you have two comforters, one with 50 ounces of 550 fill power down, and the other with 30 ounces of 700 fill power down, they will keep you equally warm but the lesser quality 550 fill power comforter will be much heavier.
