How many litter boxes does a cat need?

The widely recommended rule is n+1: one box per cat, plus one additional. A single cat household needs at least two litter boxes; two cats need at least three. This reduces competition in multi-cat homes and ensures a clean option is always available. The rationale and behaviour basis is covered in the AAHA Feline Life Stage Guidelines .

Where should I put the litter box?

Quiet, low-traffic areas with easy access. Avoid: next to the food and water bowls (cats dislike eliminating near their eating area), next to washing machines or dryers (sudden noise can startle a cat mid-use, creating an aversion), or in difficult-to-reach locations like high cupboards. For senior cats with mobility issues, ground-floor access and low-entry boxes are important — see International Cat Care's litter tray guide .

What is the best type of cat litter?

Most cats prefer fine-grained, unscented clumping litter — it mimics the sandy substrate cats instinctively choose in nature. Scented litters are designed for human preferences, not cats; a cat's sense of smell is estimated to be 14× more sensitive than a human's, making artificial fragrances potentially aversive. Silica gel and wood-pellet litters suit some cats but others reject them. If changing litter type, do so gradually by mixing the old and new litters over two weeks.

Why is my cat going outside the litter box?

House soiling is one of the most common reasons cats are surrendered to shelters, yet it is almost always addressable. Common causes: box too small, not cleaned frequently enough, wrong location, litter type aversion, inter-cat conflict (one cat guarding access), or a medical issue (UTI, FLUTD, constipation, arthritis making entry painful). Before assuming a behavioural cause, a vet check is warranted. The Merck Veterinary Manual on feline behaviour problems covers diagnosis systematically.

Should I use a covered or open litter box?

Most cats prefer open boxes — covered boxes trap odours (pleasant for owners, unpleasant for the cat), restrict movement, and can feel like an ambush site in multi-cat homes. Some cats that spray or throw litter may benefit from higher sides rather than a full lid. If your cat is already using a covered box happily, there is no need to change. The key principle: the cat's preference outweighs the owner's aesthetic preference every time.

Litter Box Setup Guide

How many litter boxes does your cat need?

The standard recommendation from behaviourists and veterinary organisations is n+1: one box per cat, plus one extra. This means a single-cat home needs at least two boxes. The reasoning is practical: cats prefer a clean box, and having options means a soiled box does not force the cat to find an alternative location.

In multi-cat homes, the extra box also reduces inter-cat conflict — one cat cannot guard all boxes simultaneously. The AAHA Feline Life Stage Guidelines cite litter box availability as a key environmental need alongside vertical space and hiding spots.

Size and type

Size

Minimum 1.5× the cat's body length (nose to tail base). Most commercial boxes are too small. A large plastic storage container (45 × 65 cm) with a low-cut entry makes an excellent oversized box for large or senior cats.

Open vs covered

Most cats prefer open boxes. Covered boxes trap odour and restrict movement. If high walls are needed (to contain scatter), cut one side low for entry rather than using a full lid.

Litter depth

5–8 cm of litter. Too shallow and cats cannot dig; too deep and small cats struggle. Clumping litter needs enough depth for solid clumps to form without touching the base.

Number of boxes

n+1 rule: one per cat plus one extra. Place boxes in different locations — not side-by-side, which functions as a single resource from a cat's perspective.

Placement principles

Quiet areas with predictable traffic — cats are vulnerable when eliminating and prefer privacy
Away from food and water bowls — cats instinctively separate feeding and elimination areas
Away from washing machines, dryers, or boilers — sudden mechanical noise causes aversion
Multiple floors if the home has more than one storey — senior cats especially need ground-floor access
Accessible at all times — do not put boxes in rooms that are sometimes closed

Litter choice

Research and veterinary consensus consistently points to fine-grained, unscented clumping litter as the preference for most cats. A landmark preference study (Cottam & Dodman, Journal of Feline Medicine and Surgery, 2007) found cats strongly preferred fine-grained litters over coarse alternatives. Scented litters — despite being marketed as odour control — are designed for human noses, not cats. A cat's olfactory epithelium is approximately 14× larger than a human's, making artificial fragrance potentially overwhelming.

Changing litter types. Never switch litter abruptly — place a new box with the new litter alongside existing boxes and let the cat choose. Gradually increase the new litter proportion over two to three weeks. Abrupt switches are a common trigger for house soiling.

Cleaning routine

Daily: Scoop all solids and urine clumps. Cats avoid soiled boxes — a full box is the single most common cause of periuria (urinating outside the box)
Weekly: Top up litter to maintain 5–8 cm depth
Monthly: Empty fully, wash box with hot water and mild unscented soap (no bleach, ammonia, or citrus-based cleaners — all are aversive to cats), dry fully before refilling
Annually: Replace plastic boxes — scratches harbour bacteria and odours that cleaning cannot fully remove

For troubleshooting house soiling, International Cat Care's litter tray resource and the Merck Veterinary Manual on feline behaviour both provide structured diagnostic approaches.

Litter box setup: the complete guide to placement, litter type, and cleaning

How many litter boxes does your cat need?

Size and type

Placement principles

Litter choice

Cleaning routine

Frequently asked questions