The number of cloth diapers used in a day depends on the age of the baby and the frequency of washing. Newborns may need 8-12 diapers a day, while older babies may need 6-10 diapers a day. It is generally recommended to have at least a two-day supply of diapers on hand, so the total number of diapers needed will depend on how often the diapers are washed.