I use flannel A LOT! you don't say if you are buying 40" wide flannel or wide flannel- if wide flannel you would need 2 yards (and will have scraps left over for a new project- if using 40" wide fabric 4 1/2 yards cut in half & stitched together you would have 78" wide (after removing salvages & using a wider seam because of the bulk of flannel) by (72+18=90) 90" allowing the extra needed for a backing. that is sewing a vertical seam- the 40" widths sewn together- the 4 1/2 yds cut in half to make the length. if you launder before cutting it you should have plenty in both directions...the shrinkage amount depends on the flannel used- a good quality double sided flannel only looses an inch or so, a light weight, thin, loose weave single sided flannel can shrink 6" or more (not always-but a possibility) the looser the weave the more the shrinkage.
Last edited by ckcowl; 07-28-2013 at 08:14 AM.