A 9 inch wide sleeve is standard for quilts to hang at shows. What are you planning to hang the wall hanging with? If it is a dowel or rod, take a piece of string and measure the circumfrance. Add your seam allowance plus about an inch and that should be a good size. You might look into the cute little curtain rings that have little teeth. They allow you to attach the teeth to the wallhanging edge and then run a rod through the rings. You can then mount the rod brackets and hang.