The diagonal of the finished block (9” unfinished, 8 1/2” finished) in Donna Jordan’s pattern is 12” . Queen mattress is 60x80. Add your overhangs for the sides and bottom plus 3” (approx.) for what’s last with the quilting and you will have your ideal size for the quilt. Divide the width by 12 to get the number of blocks across and the length by 12” to get the number of blocks down. Multiply the blocks for the width and length to get the number of blocks you need.