The latest new feature added to Quilting Studio is the Fabric Estimator. Just select the Fabric Estimator in the menu on the upper left. The page has a drop down menu of your saved quilts. Select your quilt and all the fabrics used in your quilt will show up. Along side them will be the estimate of how much fabric will be needed.
The estimates use a quarter-inch seam allowance all around each shape. The amounts are given in yards of fabric. This assumes a 45 inch wide piece of fabric and gives you the length that will be needed.
Give it a try: Quilt Fabric Estimator. This function is available for subscribers.