If your goal is to make a double or full size memory quilt, then you are on the right page.  The measurements of a full or double bed is 54×75 inches.  Remember this is the size of the “bed” not the size of a quilt.  The average memory quilt or blanket hangs off the sides and the end of the bed about 12 inchs.  So if you are making a double or full size memory quilt, your finished size would be 78×87 inches, (54+24=78, and 75+12=87).  If you want your quilt to hang over even more, just add more inches.  Just be sure to add the side inches twice since there are two sides to a bed.