Bed linens are sized by the terms "queen size" and "king size" to indicate the standard bed size length and width they fit. Actual dimensions of individual queen or king comforters vary.
Queen size comforters fit a mattress and box spring that are 60 inches across by 80 inches in length. They are generally 86 inches wide by 94 inches long.
King size comforters fit a mattress and box spring that are 78 inches across by 80 inches in length. They are about 96 inches across by 110 inches in length.
A deep pillow-top mattress will require a comforter on the larger end of the range to allow for a longer drape over the sides of the mattress.
A fluffier comforter will require a few extra inches to account for the loft of the filling. A queen or full size down comforter is about 90 by 98 inches, while a king down comforter measures about 98 by 108 inches.
Comforters drape a few inches below the top mattress, while a bed skirt covers the box spring. To avoid the need for a bed skirt on the box spring, choose a bedspread that reaches the floor.