Three king-sized pillows, two blankets just barely fit into the over-sized sandwich baggy. Apply a little minor vacuum and it shrunk to roughly 1/3 the previous volume – the better to transport in Smart ForTwo!
EDIT: This first bag was stuffed at a normal level, and weighs in at 8 kg, not too shabby. The second test vacuum bag has two quilts and two duvets, one of the latter still in its cover. It took 20 minutes just to get everything stuffed in and ziploc closed. All vacuumed out it tips the scale at only 150% of the first, 12 kg, but man that was a ton of work wrestling it all together. Two bags for $20 CAD are cheaper than snake-wrestling too much into too small. And it did not pack any smaller, as a percentage of the uncompressed size, possibly even less since it was pre-compressed by me jamming it into the bag.