Fill Power is a term used that tells the quality and insulating value of the down. Technically fill power is a measurement of the amount of space 28grams of down will occupy in cubic inches when allowed to reach its maximum loft. The higher the fill power the higher the quality of down.

To test for fill power in Europe 28grams of down is placed in a 289mm diameter cylinder and then a compression weight of 94 grams is placed on this down, the level that the compression stops gives the fill power rating.

The difference between European testing and American testing is the diameter of the cylinder used. In the US they use a 241mm diameter cylinder and a 68gram compression weight therefore the down will loft higher and give a higher fill power reading. This is why we have noted both the European fill power and the US fill power rating to ensure you are fully informed on your purchase.