48" square would be fine, especially if the playpen is square shaped. The ones that I made for my children for naptime at program have been 36" x 48" just enough to keep them comfy during nap. And their easy to wake when time to go home.
Help, my neighbours daughter is having a baby shortly and I want to make her a cot quilt. My experience of babies is limited to puppies and kittens. Can anyone tell me the size that a cot quilt is supposed to be. I feel really stupid having to ask this but I know that someone out there will have the answer. Thank you.