When I made a custom quilt bedspread for my new bed, I measured my actual bed. My bed is a queen, with a Temperpedic mattress (which tend to be thicker than some) on a canopy frame (again, taller than average), so my quilt bedspread is 110” x 112”. If you are making it for your bed, or whomever’s bed, measure the bed and make it that size.