When producing a queen copy, you have to convert the desired finished size to fabric yardage to be aware of how much stuff you need. Based on a standard queen comforter size of 90 inches wide by 95 inches long, you want a bare minimum of 11 yards, but 12 yards adds additional for straightening the cloth. Buy an additional one to two yards if the cloth has a stripes or pattern you have to fit.
A queen comforter requires two textile sides, each 91 inches by 96 inches before you sew them together with 1/2-inch seams. The sides are made with a center panel 96 inches long by the width of the cloth, and also half-width panels sewn to the sides of the middle bit. With 54-inch fabric, then you will need two pieces each 96 inches long, or 2 3/4 yards each. This adds around 5 1/2 yards per side, or at least 11 yards for the comforter and 12 yards for duvets. You may use the identical yardage to get 45-inch fabric, but the comforter may finish marginally narrower once you cut the selvages and allow for seams.
Queen Flat Sheets
Simplify the sewing using a queen flat sheet for a single or both sides. To acquire a completed 90-inch width, look for sheets which are at least 92 inches wide, as you will need to cut the side selvages and allow for the seams. Flat sheets are generally longer than the comforter length, so cut off the excess to get the needed 96-inch span.