blackribbongirl - I would probably say 3 dozen depending really on how many times you change your baby during the day - you have to take into account drying time etc... Cushie Tushies can be tumble dried but it does shorten the life span of the elastic. If you dont use them already perhaps just get a trial pack to start out with. My son is 9kgs and they still look bulky on him now - I have just sold most of mine and mainly use babybeehind magicalls as they arent as bulky and dry really quick.