chamber LxHxW / 800
I calculated the first 2 chambers and then when a remainder was left I subtracted in sequence. It was perfectly even as the baffles decreased in size.
for overstuff, (I added more later) but primarily put in about 10% more down per chamber
of course, this is much easier with a rectangle quilt... lets say you have a baffle 48x6x2" high. 576cu in./800=.72oz + 10% overfill is ~.8 ounce
what the heck, lets make it nice and fat and do 1 ounce per chamber.
if your quilt is 7' long, you will need 14 ounces and that will likely give you about a 3 to 3.25" loft
now we're talking 25°
down can be purchased from Thru-Hiker.com or Speerhammocks.com
i have used both, and found the quality to be similar