Calculate fill power, down volume, or down weight, and estimate down needed from item dimensions, loft, fill power, and overfill percentage.

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Use a fill-power test volume and mass from the same method. Dimension estimates assume uniform loft and do not predict warmth or a temperature rating.

Related Calculators

Fill Power Formula

The following formula calculates fill power from a test volume and mass of down measured under the same specified test conditions.

FP = V / W

Variables:

  • FP is the fill power
  • V is the volume of down
  • W is the weight of down

Divide the test volume by the down mass, using consistent units. Cubic inches and avoirdupois ounces give in³/oz; cm³ and grams give cm³/g, which is numerically equal to L/kg. Unit conversion does not make different test methods equivalent.

What is Fill Power?

Fill power measures down’s loft under specified conditioning and compression tests, often reported as cubic inches per ounce or cubic centimeters per gram. Higher fill power can provide more loft per unit mass, but finished-product warmth also depends on fill mass, construction and conditions. The dimension and pillow modes estimate mass from a uniform-loft volume and chosen overfill; they do not provide a temperature rating.

How to Calculate Fill Power?

The following steps outline how to calculate the Fill Power.

  1. First, determine the volume of down (V).
  2. Next, determine the weight of down (W).
  3. Finally, calculate the fill power using the formula FP = V / W.
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Volume of down (V) = 600 cubic inches

Weight of down (W) = 2 ounces