For differential cut you use the formula:


  • b1 = Inner Baffle spacing
  • b2 = Outer Baffle spacing
  • H = Baffle height
  • L = Lenght of Baffle
  • FP = Fill Power of Down used

Your finding the area of Trapezoid and then finding the volume of a trapezoidal solid. This will give you amount of down per each chamber.

I can tell you that I made my UQ with exactly the same measurements as the OP.

  • Inner Baffle Spacing 5.5 inches
  • Outer Baffle Spacing 6.25 inches
  • Baffle height 2 inches
  • 8 Chambers
  • 1.25 ounces of 850FP down per chamber

Honestly though a little more, maybe 1.5oz per chamber, wouldn't hurt to fill it out a bit more.