The average size of a full size comforter is 80 x 90 inches. Some comforters may be slightly larger or smaller depending on the manufacturer. The comforter will hang over 13 inches on each side of the bed. The length of the comforter will hang over the foot of the bed by 15 inches.
Full/queen comforters are made to fit full size and queen size beds. The queen size bed is 60 x 80 inches. The comforter is 88 x 88 inches. On a full size bed, the comforter will hang over the sides 17 inches. The length of the comforter will hang over the foot of the bed by 13 inches.
Down comforters are slightly larger than a regular full/queen size comforter. The down comforter is a full/queen comforter at 90 x 98 inches. The sides of the comforter will hang over the side of the bed by 18 inches. At the foot of the bed, the comforter will hang down 23 inches.
The duvet is used to cover a comforter or change the look of the bed. The comforter goes inside of the duvet cover. Duvets will fit a full/queen size comforter measuring 88 x 88 inches. When you use a duvet with your comforter, measure the comforter and find a duvet to match that size.