Of course the comforters will vary a little bit from manufacturer to manufacturer and style to style in how much extra material you get. If you assumed that the comforter was the exact same size as the matress, however, a queen would be 60"x80" and the king would be 76"x80". Although sizes vary from manufacturer to manufacturer, a good rule of thumb is 86"x94" (8084 sq in) for queen and 110"x96" (10560 sq in) for king. In area, that is a difference of roughly 25%.