Baby quilts come in all sizes. Some are simply 36" X 42" ( a yard of fabric) sometimes they are 30" or so square, some are crib sized, you can make it any size that you like. I think crib sized batting is 45" X 60" -- which would work for a quilt 40" X 55" or smaller. Depends on the use, ( wrap the new born? Use on the floor? Crib sized? New baby gift/ keepsake? One to last be used for a couple years? You will need to decide a few things, then make it the size you want it to be-- there is no ( a baby quilt is--- this size)