1) Diapers. For a newborn, start with a dozen diapers for each day you don’t want to do laundry. (I want to do laundry every three days, so I need three dozen.) Get 6-8 covers, if you’re using prefolds or fitteds. You can always buy more if you need them! (Want to see what my newborn stash looks like? I talk about it here on my blog.)
For an older baby, you probably have a good idea of how many times you change your baby during the day. You’ll find that you change the baby more often when he’s wearing cloth, so add a few diapers to your daily diaper total and that’ll tell you how many to buy! Most people use 2-3 dozen diapers and 6-8 covers in the medium and large sizes.
2) Wipes. Plan on a dozen per day.
3) Diaper Pail. You can use a step-lid garbage can. Pair it with a pail liner if you wish. Or, skip the pail and just use a wet bag or pail liner.
4) Wet bags. For on-the-go diapering. A small size will work for day trips and errand-running, a larger bag will be suitable for longer trips.
5) Optional accessories. Some people like to use diaper liners and doublers. You might want a changing pad or two.