I made my first down underquilt as few weeks ago it was a karo-step design with 2" of loft. I made the baffles 2” with 20% over-stuff. I did get the 2” loft but the down is a lot looser (large open pockets) than I was hoping for and the down can easily migrate.
It made me wonder if I got the 800+ fill power that I ordered or if I should have change my design to use 1 or 1.5 inch baffle and calculate the down needed for 2” loft.

So quilt makers, do you set you baffle height the same as the loft that you are trying to obtain?