The instructions on CraftyChicsBlog uses 127 diapers for a four-tiered cake, 64 diapers for a three-tiered cake, and 26 diapers for a two-tiered cake as of 2015. The number of diapers needed varies, however, according to the size of the cake and the number of tiers.
PersonalCreations.com offers different ideas for diaper cakes, such as using 60 diapers and including a combination of diapers and washcloths along with other essential items for parents of newborns to construct the cake.
Diaper cakes are not edible cakes. They can serve as decorative centerpieces for baby showers or humorous yet useful gifts for expectant mothers.