Fill Power   Turbidity   Oxygen   Internal Testing   Independent Outside Testing

There are several industry accepted tests for feather and down fill used in bedding and other finished products. This section will help explain three of the most prominent tests and explain the importance of both internal and independent outside testing.

Fill Power

Fill power is a measure of how ‘fluffy’ or ‘lofty’ down is. The higher the fill power, the more it traps air. It’s trapped air that keeps the sleeper warm. The actual test involves weighing and filling a cylinder tube with 28.4 grams of down. A specially calibrated weight is then placed on top of the cylinder and its weight is slowly allowed to fall onto the down for 60 seconds. The tester will observe the markings on the side of the cylinder where the weight stops. The higher the fill power, the loftier the down is and the better an insulator it is. This test is performed again 24 hours later and the results are compared and averaged. The typical fill power is approximately 500 and can reach as high as 800 or more in premium bedding or special sleeping bags. As fill power increases, the value of the down goes up significantly.

Fill power can be influenced by a variety of factors including: sitting in transit, humidity, temperature, static electricity and timing issues.


Turbidity is a technique that involves measuring 10 grams of down and placing it into a special beaker with 1 liter of water. This beaker is then sealed up and vigorously shaken for 15 minutes. After 15 minutes, the mixture is strained using a special filter and placed into another long tube. The tester will visually look down into the opening of this cylinder to see if a pair of crosshairs on the bottom are visible. On the outside of this clear cylinder are markings with measurements that indicate the amount of liquid in the container. The cylinder is filled to the top where the marking is. If the tester has trouble viewing the crosshairs the beaker is emptied until they are visible from the top. 550 is an excellent level and the highest measured in the United States (150 is considered acceptable–where as some Japanese companies prefer 800). In essence, the higher the turbidity number, the ‘cleaner’ the down.


The oxygen test is a technique where the presence of organic materials is measured. Organic materials are found in unwashed products that come from the meat processing plants-including blood from the waterfowl. The test is complicated but basically involves applying specially measured chemicals to the same water used for the turbidity test. The lower the Oxygen count, the less organic materials that are present in the finished product. A good Oxygen test measures 4.5 or lower.

Internal Testing

Down testing is best performed after the down is washed and dried but before it is used in the final products. This allows tighter control over products all the way through final production. Some feather and down processors do their own internal testing to constantly monitor the quality of their merchandise and be able to make washing adjustments in real-time.

Independent Outside Testing

There are many labs for the testing of down products–two are: The International Down and Feather Laboratories (IDFL) and the Independent Down Laboratory (IDL). Both of these facilities regularly test down from both down processors and retailers of the finished goods. Many larger retail and catalog chains request officially certified tests from these companies to audit their inventory of down product. Tests can usually be performed within a few days and cost up to a few hundred dollars.

FTC Guideline: Any product with at least 75% down clusters may be labeled as “Down”. The remaining 25% are usually comprised of down and feather fibers and small feathers (less then a few cm – can be up to 6 cm).