It depends from how you want to use them: If you want to use them in place of disposable sanitary napkins, then count how many of these you use per day and multiply for 3. In this way, you will have enough pads in your stock to be able to wash and dry them cyclically during the period. If you want to mix their use with that of disposable sanitary napkins, I suggest you to buy 3-6 units If you will use them together with tampons or a menstrual cup, then I suggest you to only buy panty liners and regular, from 2 to 4 units If you want to use them only in the days before your period, choose the night or postpartum model, 2 pairs will be enough