a 24" square for Premies, and a 36" square for Newbies should be good. What a wonderful thing you are doing. I am sure that they will be appreciated. The premie size is great because Mommy always feels like the baby gets lost in a bigger size. I am doing quilts for the families of Hospice patients because so many of us have sat at a bedside night and day, and most folks think of the patient, but the caregivers need a hug too