PrettyLitter requires a minimum depth of 2" in a litter box being used by one cat. For multi- cat households, use one bag of PrettyLitter per cat. For example, if two cats are using one litter box, or even if each cat has their own litter box, but one is used more than the other, we suggest two bags per box. If your cat is on the larger side, we recommend you get your litter box up to at least 3" of depth for optimum absorption. There are many different sizes of litter box, and every household's litter box usage is different, so if you ever need more or less litter, we're happy to help anytime. Feel free to contact our CS team at email@example.com or 800-838-3381.