Newborns typically soil an average of 8 to 10 diapers a day and for that reason, buy at least 20 cloth diapers, to begin with. 20 might sound like a big number but when you also account for how quickly newborn babies grow and how you would not have a lot of time to invest in the laundry, at least after the first few weeks post-delivery, 20 should be a perfectly comfortable number.