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Cat Litter Box Size Calculator

Find the right litter box size, how many boxes you need, and the best litter type for your cat. Based on the veterinary 1.5× body length rule and multi-cat household guidelines.

The 1.5× rule

A proper litter box should be at least 1.5 times the length of your cat from nose to base of tail. Most commercial "regular" boxes are too small for adult cats over 10 lb. Cats compensate by hanging out the side, kicking litter, or avoiding the box entirely.

Box size by cat weight

The N+1 multi-cat rule

Veterinary behaviorist standard: number of cats + 1 boxes, spread across the home. So 2 cats = 3 boxes, 3 cats = 4 boxes. This prevents "guarding" behavior where one dominant cat blocks others from access, which leads to inappropriate elimination outside the box.

Boxes should be in different rooms/areas — multiple boxes side-by-side count as ONE territorial location, not two.

Litter type by cat

Litter depth and cleaning

For tested cat boxes and litter, see our cat product reviews.