While you may save money buying in bulk, if you are getting a newborn size you won’t use that many. Many babies grow out of their newborn size rather quickly. Also, if you are unsure which brand you like, it is best to buy smaller packs and test out your favorites. After that, younger infants will go through 10 to 12 diapers a day. As infants get older, they start using 6 to 8. After you find a brand you like and your baby is in a steady size, buying economy sizes can save a lot of money.