Read the wrapping on the batting at the store. You also need to take into account now closely it needs to be quilted to wear well. Cotton, unless it is bonded to a scrim, will sort of disintegrate over time and leave little lumps in your quilt if not quilted closely. Polyester is puffier and I actually prefer it for baby quilts. Warm and Natural is okay but flatter. You can also use fleece fabric for batting and also as batting and backing together, just one layer. There are lots off choices. Choose what fits your preferences and your purse.