🐱 Litter Box Count Calculator

The "N+1 rule" for litter boxes (provide one box per cat, plus one extra) is a guideline widely cited by veterinary behaviorists and referenced throughout animal welfare and shelter medicine literature. Cats can experience sharing a litter box as stressful or treat it as contested territory, and having an extra box available is commonly believed to help reduce inappropriate elimination (accidents outside the box).


This calculator also factors in homes with multiple floors: regardless of cat count, it recommends at least one box per floor, since cats may not want to travel between levels every time they need to go. This is a general reference guideline, not a substitute for individual advice from a veterinarian or feline behavior specialist.

Box count matters, but so does size. A commonly cited veterinary-behaviorist guideline is that litter box length should be at least 1.5 times the cat's body length (measured from the nose to the base of the tail). A box that's too small can make it hard for a cat to turn around fully or dig/cover after eliminating, which can lead to litter box avoidance.

For example, a cat with a 18-inch (45cm) body length would need a box at least 45 × 1.5 = 67.5cm (about 26.5 in) long. Many commercially sold litter boxes fall short of this, which is why some owners repurpose large storage bins or under-bed containers as litter boxes.