A Lap Quilt that is 64 x 64? My mother (age 92) and her church ladies make lap quilts for _retirement homes and the local Veterans' hospital that are approximately 45 x width of fabric. If you get 3.25 yds = 117inches. Cut in half and sew the selvages togethe and the piece is 58.5 x 84 (or the width of the fabric x 2). To get a backing of 64 x 64 you would need 3 2/3 yds of fabric. And as someone else already mentioned, you'd still need binding, unless you were going to birth the quilt. Although the extra you would have after sewing the selvages together might be enough for binding. I agree, tell them to get a sheet either from Wally's or a local thrift shop.