If you are going to use spray adhesive to quilt then the overage doesn't need to be that much. I usually have 1-2 inches overage when I quilt because I don't want to waste; however, what's really beneficial when using the spray adhesive is that you can use all your scrap pieces of batting. Just lay them side by side and don't lap the edges over each other. I found this to truly be a blessing since I keep most of my batting scraps. I am now using them on baby quilts and lap quilts since most of the small pieces are easy to use with the spray. This has saved me a boatload of money since I don't need to keep buying batting for small projects and there is truly no waste. Just another way to spend my money wisely. Good luck and please post pics when you are done.