The AAFP/ISFM guidelines from two feline vet groups, International Cat Care, ASPCA and Humane World for Animals give one litter box per cat plus one extra. RSPCA gives one per cat and calls a spare a good idea.
How many cats?
How many litter boxes
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Where the sources differ
The AAFP/ISFM house-soiling guidelines, from the American Association of Feline Practitioners and the International Society of Feline Medicine, give a single cat two boxes in two separate places. For more cats, they give at least one more box than cats, though not as an absolute requirement. International Cat Care treats litter trays like food and water bowls, beds and scratching posts: one per cat, plus at least one extra.
Where to put them
- AAFP/ISFM: at least one box on each level of a home with more than one floor.
- ASPCA: a quiet, easy-to-reach spot, with one box per floor in a multi-level home.
- Humane World for Animals: in different areas of the home.
- RSPCA: away from where your cat eats and sleeps.
How deep to fill them
| Source | Depth |
|---|---|
| International Cat Care | about 3 cm (1.2 in), the depth research shows cats prefer |
| AAFP/ISFM | at least 1.25 in (3 cm) of fine, sand-like, unscented clumping litter |
| ASPCA | a shallow bed: one to two inches rather than three to four |
| RSPCA | a deep layer of litter |
RSPCA spot-cleans the tray every day and replaces the litter at least once a week.
The box itself should be one and a half times your cat’s length: see what size litter box.