How Many Litter Boxes Does a Cat Need? Size, Spots, and Cleaning

Most litter box setups are designed around the person: one box, tucked out of sight, small enough to fit the space. Cats have their own preferences, and when a setup does not suit them, the result can be accidents on the rug. The ASPCA says at least 10% of all cats develop elimination problems.

Veterinary feline specialists have written down what a cat-friendly setup looks like. The main sources are guidelines from the American Association of Feline Practitioners (AAFP) and the International Society of Feline Medicine (ISFM) on house-soiling, and the AAHA/AAFP Feline Life Stage Guidelines. Here is what they recommend.

1. How many boxes: one per cat, plus one

The AAHA/AAFP guidelines give the rule of thumb as one litter box for each cat plus one additional box, or one per social group plus one if you know how your cats group themselves. The ASPCA uses the same "plus one" rule.

The AAFP/ISFM guidelines add that a single-cat household should have two boxes in two separate locations. They also call the multi-cat rule a historical rule of thumb rather than an absolute requirement: cats that are socially bonded may share more readily, while cats that are not should have separate litter stations. In a multilevel home, they recommend at least one box on each level.

2. Where to put them

From the AAFP/ISFM guidelines:

• Spread boxes out. Cats perceive boxes placed side by side as one large box. If two must be near each other, angle the openings at right angles or around a corner so a cat can leave without running into another cat.
• Keep food and water away from the litter box.
• Give an escape route. The AAHA/AAFP guidelines suggest quiet, convenient spots that provide a way out if needed.

If you need to move a box, the AAFP/ISFM guidelines suggest doing it gradually, a few inches a day, after the cat is using it consistently.

3. How big: bigger than most store boxes

The AAFP/ISFM guidelines say research suggests box size matters as much as the number of boxes, and in general, bigger is better. They recommend a rectangular box about 1.5 times the length of the cat from nose to base of tail. In one study they cite, adult cats preferred a box of 34 by 15 inches over a smaller one.

The AAHA/AAFP life stage guidelines give a similar 1.5 times rule (they measure to the tip of the tail) and say plainly that most manufactured boxes are not large enough. Both suggest alternatives such as large storage containers; AAFP/ISFM also mentions under-bed storage boxes and concrete mixing trays from home improvement stores.

A quick example: a cat measuring 18 inches from nose to base of tail would need a box about 1.5 x 18 = 27 inches long.

Sides and entry. The AAHA/AAFP guidelines say edges should not be too high for kittens or senior cats to get in and out easily. The AAFP/ISFM guidelines picture a storage container with one side cut down as a low-entry option for an older cat.

4. Covered or open?

The AAFP/ISFM guidelines report that cats are about evenly divided between preferring large covered boxes and uncovered ones, and that regular cleaning may matter more than the cover. They recommend open boxes whenever possible, because they make monitoring and frequent scooping easier, and note that small covered boxes can make it hard for larger cats to posture normally.

5. What to put in it

• Unscented litter. The AAFP/ISFM guidelines say cats often find aromatic litter and litter deodorizers offensive. The AAHA/AAFP guidelines note unscented clumping litter may be preferred for cats with a history of urinary problems.
• Offer choices. Because individual preferences are documented, AAHA/AAFP suggest testing preferences with different litters in separate boxes.
• Depth. The ASPCA says cats usually prefer one to two inches of litter.

The AAFP/ISFM guidelines also make a useful point: litter is marketed to people, and no product removes the need for regular cleaning.

6. How often to clean

The two guidelines differ slightly on soap: AAFP/ISFM allow soap and hot water, while AAHA/AAFP say to avoid soap or strong chemicals and that hot water is best. Both rule out harsh products. AAHA/AAFP also say boxes should be replaced periodically, not just cleaned.

7. When it is not the box

A cat that suddenly avoids the box may be sick. The ASPCA lists urinary tract infection, feline interstitial cystitis, and kidney stones or blockage among the medical causes, and says a cat straining with little success needs a veterinarian immediately. The AAHA/AAFP guidelines say urinary tract blockage can be life-threatening and urge prompt veterinary care. They also say cats should never be punished for eliminating outside the box or carried to it as punishment.

8. Key takeaways

• Provide one litter box per cat plus one; a single cat should have two boxes in separate places.
• Spread boxes around the home, one per floor, away from food and water.
• Aim for a box about 1.5 times the cat's body length; the AAFP/ISFM guidelines cite 34 by 15 inches as preferred in one study.
• Open boxes with 1 to 2 inches of unscented litter suit most cats.
• Scoop at least daily, wash every 1 to 4 weeks with soap and hot water, and see a vet promptly for sudden changes or straining.