Litter Box Calculator
Find how many litter boxes and litter you need.
Roughly 10 lb per cat
Results update as you type.
How it works
Providing the right number of litter boxes and enough litter keeps cats healthy and happy, and this calculator estimates both. You enter your number of cats and optionally the litter each cat uses per month, and it returns the recommended number of litter boxes and the total monthly litter needed. The number of boxes follows the well-established n+1 rule from veterinarians and cat behaviorists: one box per cat, plus one extra. So two cats should have three boxes, three cats four boxes, and so on. This reduces competition, territorial disputes, and litter-box avoidance — a common cause of cats eliminating outside the box, which is one of the top behavioral reasons cats are surrendered. Boxes should be placed in different, accessible, low-traffic locations rather than all together, and in a multi-level home, on each floor. For litter usage, a rough average is about ten pounds per cat per month with clumping litter and regular scooping, though this varies with the litter type, how often you fully change it, and each cat's habits. Knowing the monthly amount helps you budget and stock up. Keeping boxes clean is essential — scoop daily and change litter regularly — since cats are fastidious and may avoid a dirty box. Enter your number of cats to find the boxes and litter you need.
Boxes = cats + 1; monthly litter = cats × litter per cat
The widely recommended rule is one litter box per cat plus one extra, so the number of boxes is the number of cats plus one. Monthly litter is the number of cats times the litter each cat uses per month, roughly ten pounds on average.
Source:Feline care guidelines (n+1 rule)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter number of cats.
- 2
Adjust the options
Adjust litter per cat per month if they apply — sensible defaults are already set.
- 3
Read your result
Recommended litter boxes updates instantly as you type — no button to press.
Frequently asked questions
How many litter boxes do I need?
The standard recommendation is one litter box per cat plus one extra — the n+1 rule. So two cats need three boxes, three cats need four, and so on. This reduces competition and litter-box avoidance. Place the boxes in separate, accessible, quiet locations rather than grouping them all in one spot.
Why the extra litter box?
The extra box beyond one per cat gives cats options and reduces territorial conflict, waiting, and stress, which can otherwise lead to cats avoiding the box and eliminating elsewhere. Cats can also be picky about using a box another cat just used. The n+1 rule is recommended by veterinarians and behaviorists to prevent these common problems.
How much cat litter will I use?
A rough average is about ten pounds of clumping litter per cat per month with daily scooping and periodic full changes, so two cats use around twenty pounds. Actual usage varies with the litter type, how often you change it completely, box size, and each cat's habits. Track your own usage over a month to refine the estimate.
Where should I put the litter boxes?
Place boxes in separate, quiet, accessible locations rather than all in one area, so cats aren't forced to share a single spot. In a multi-story home, put at least one box on each floor. Avoid noisy or high-traffic areas and keep boxes away from food and water. Good placement encourages consistent use and reduces accidents.
How often should I clean the litter box?
Scoop clumping litter at least once a day, and fully change the litter and wash the box regularly — often every one to a few weeks depending on the litter and number of cats. Cats are clean animals and may refuse a dirty box, leading to accidents. Keeping boxes clean is one of the best ways to ensure cats use them reliably.