When is Fill Power measured for finished product claims?

Fill Power is first tested immediately after the down is washed, dried, and sorted. This first test for fill power represents the real or “original” fill power for the down. This first or original test is the basis for all labels, advertising, and marketing claims.

Why do subsequent Fill Power measurements drop?

Compression, shipment, storage, and finished product assembly cause fill power to drop. Comforters, pillows, and even bulk down may drop 5-20%. Jackets and sleeping bags may drop 10-40%.

Will the Fill Power ever return to its original value?

Yes, consumer use of a product can return fill power to original value. Air circulation, and moisture all help return fill power to the original test value. Consumer use of products increases fill power:

  1. Sleeping bag fill power will improve during use (sleeping in the bag).
  2. Comforters show increased fill power after use (sleeping under the comforter).
  3. Wearing jackets or vests will improve fill power.

Also, the regular care and cleaning of finished products help return fill power to original values:

  1. Regular shaking and lofting of down products will help circulate air.
  2. Placing a product in a home tumble dryer will help add warmth and air circulation to the down.
  3. Washing down products in plain water or a mild down soap adds moisture and warmth.

How should down be conditioned in a laboratory before Fill Power testing?


Down tested immediately after washing and sorting usually needs only box conditioning (climate controlled box for 3+ days). However, IDFB protocol requires tumble-dry and/or steam conditioning even for these tests.


A 50g sample from down bales or finished products is tumbled in a home tumble dryer before box conditioning.


Products like sleeping bags and jackets can be water rinsed (in a home washer) before testing. This effective method demonstrates how fill power changes after a consumer cleans the product.


OFFICIAL IDFB METHOD. During the June 2005 IDFB meetings in Kyoto, Japan, IDFB approved steam as the “official” world-wide conditioning method. Use steam for bulk down, all pillows, comforters, jackets, sleeping bags, etc. that have been compressed, stored, and/or shipped.

How long can original Fill Power be maintained?

Research on this subject is ongoing. Using steam conditioning, IDFL has been able to return fill power to original value after 5 years in cold, compressed storage.

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