Put a litter box somewhere quiet and easy to reach, away from your cat's food and water, and give your cat more than one to choose from. The main veterinary and welfare bodies broadly agree on that much. The usual starting number is one box per cat plus one extra, with the boxes in different spots rather than lined up together.
The rest is upkeep: litter a few centimeters deep, scooping at least once a day, a full wash about once a week, and moving a box in small steps rather than all at once. The authorities differ on some of the details, mostly litter depth and how often to wash the box, and we note where.
How many litter boxes do you need?
Most cat-care authorities start from one litter box per cat, plus one extra. Cornell's Feline Health Center, the ASPCA, VCA and International Cat Care all give that formula, and the RSPCA recommends one tray per cat with a spare as a good idea. So two cats get three boxes, and three cats get four.
It is a rule of thumb rather than a measured threshold. The 2014 AAFP and ISFM house-soiling guidelines call it the "historical rule of thumb" for multi-cat homes and say it "is not an absolute requirement". A Cats Protection article by veterinary nurse Vicky Halls makes the same point: the formula is not based on hard evidence, though many agree it is sound advice.
The AAFP/ISFM guidelines are specific about single cats: a home with one cat should have two boxes in two separate locations. Cats that are socially bonded may share boxes more willingly, while cats that are not should have their own litter stations. A home on more than one level should have at least one box on each level.
What each source recommends
| Source | How many boxes | Litter depth | Scooping | Full clean |
|---|---|---|---|---|
| AAFP/ISFM house-soiling guidelines (2014) | Two for one cat; at least one more than the number of cats in multi-cat homes | At least 1.25 in (3 cm) | At least once a day | Every 1 to 4 weeks |
| Cornell Feline Health Center | One per cat, plus one | About 1 to 2 in | Daily, for clumping litter | Often enough to look and smell dry and clean |
| ASPCA | One per cat, plus one | 1 to 2 in | At least once a day | Once a week |
| RSPCA | One per cat, plus a spare | Varies: some cats like it shallower, some deeper | Every day | Litter replaced at least weekly |
| International Cat Care | One per cat, plus one | About 3 cm | At least once a day | At least weekly |
| VCA | One more than the number of cats, in at least two places | Not stated | Daily | About once a week; every 2 to 4 weeks may do with clumping litter |
Where should you put a litter box?
Put a litter box somewhere quiet, private and reachable at any hour, away from where your cat eats and drinks. That is how Cornell's Feline Health Center sums up what most cats prefer, and the AAFP/ISFM guidelines add that putting food and water close to a box discourages cats from using it there.
Busy, noisy spots are the ones that tend to fail. The ASPCA says to keep boxes away from high-traffic areas. VCA notes that cats may avoid a box that is hard to reach or sits by a noisy or busy area, and gives a box near a furnace or washing machine at the far end of a basement as an example. The Cats Protection article adds full-length windows, cat flaps and external doors to the list.
Cats also want to see what is coming. The ASPCA describes the ideal spot as quiet but not "cornered", and the Cats Protection article suggests a discreet corner or a spot against a wall, where the cat has a full view of approaching trouble with its back protected. In a home with several cats this matters more, because a box with one way out is easier for another cat to block.
Litter box placement checklist
- Quiet and private, away from heavy foot traffic
- Reachable at any hour, with no door that can shut the cat out
- Well away from food and water bowls
- Not next to a washing machine, furnace or other noisy appliance
- Not beside a cat flap, an external door or a full-length window
- A clear view of the room and an easy way out
- At least one box on every floor of the home
- Boxes in different places, not lined up side by side
- Low sides for a kitten or an older cat
Why not line the boxes up side by side?
Two litter boxes placed side by side do the job of one. The AAFP/ISFM guidelines say cats perceive litter boxes placed next to each other as one large box. Separate spots also make it much harder for one assertive cat to guard every toilet in the house, a point the Cats Protection article makes about multi-cat homes.
If two boxes have to share a room, the AAFP/ISFM guidelines say their openings should not face each other. Set them at right angles, or around a corner from each other, so a cat can leave one box without walking straight into another cat.
How big should a litter box be?
A litter box should be about one and a half times the length of your cat, measured from nose to base of tail, which is larger than many boxes sold for cats. The AAFP/ISFM guidelines, International Cat Care and the Cats Protection article all suggest that size. In a 2014 study in the Journal of Veterinary Behavior, cats in 43 homes given a regular box and a larger one chose the larger box more often.
Kittens and older cats need low sides so they can step in easily, as Cornell notes. The AAFP/ISFM guidelines also favor open boxes where possible, partly because an open box makes it easier for you to see when it needs scooping.
Choosing the box and litter
How deep should cat litter be?
Most guidance puts cat litter at about 3 cm deep, or one to two inches. International Cat Care calls about 3 cm ideal, and the AAFP/ISFM guidelines recommend at least 1.25 inches (3 cm) of fine, sand-like, unscented clumping litter. Cornell says most cats prefer unscented, finer litter about one to two inches deep, and the ASPCA suggests one to two inches rather than three to four.
The sources do not fully agree. The RSPCA says some cats prefer shallower litter and others deeper, and the Cats Protection article recommends 3 to 4 cm. If your cat perches on the rim with only one or two feet inside, the AAFP/ISFM guidelines say that may signal a dislike of the litter or of soiled litter. Their suggestion is to offer boxes with different litters and depths and let the cat show its preference.
Skip the scent. The AAFP/ISFM guidelines say cats often find scented litter and litter deodorizers offensive, and advise against liners and deodorizing powders. The RSPCA warns that scented litter may put a cat off its tray.
How often should you clean a litter box?
Scoop at least once a day
Every source on this page sets daily scooping as the minimum. The AAFP/ISFM guidelines say to remove waste at least once a day and add litter as needed, and note that no product removes the need to clean and maintain boxes regularly. The Cats Protection article suggests scooping clumping litter twice a day.
Top the litter back up
Refill after scooping so the depth stays where your cat likes it. VCA's house-soiling advice makes the same point.
Empty and wash the whole box regularly
Weekly is the most common advice: the ASPCA, VCA and International Cat Care all say about once a week, and the RSPCA says to replace the litter at least weekly. The AAFP/ISFM guidelines give a wider range of every one to four weeks and note that behaviorists differ on it, and VCA says a box of clumping litter may only need a full change every two to four weeks.
Wash with something mild and unscented
The AAFP/ISFM guidelines say to use soap and hot water and avoid strong chemicals or ammonia-based products. The ASPCA suggests warm water with unscented soap, baking soda or no soap, because a cat can develop an aversion to a scented cleaner. The Cats Protection article warns against phenol disinfectants, which it says are toxic to cats.
How do you move a litter box?
Move a litter box gradually, a few inches a day, rather than in one jump. Cornell's Feline Health Center advises moving the box just a few inches a day toward the spot you want, once your cat is reliably using it. VCA's behaviorists say to move it only 6 to 8 inches at a time, and the AAFP/ISFM guidelines also describe moving it several inches a day.
Wait for steady use before you start. The AAFP/ISFM guidelines say that once a cat begins using a box in a new place, it should stay there for at least two weeks, even if the spot is inconvenient. Only when use has become consistent is it time to edge the box toward a place that suits the people in the house.
Questions about litter box placement
Does one cat really need two litter boxes?
The AAFP/ISFM house-soiling guidelines say a single-cat home should have two boxes in two separate locations, and the one-per-cat-plus-one formula used by Cornell, the ASPCA and International Cat Care also comes to two. The RSPCA calls a spare a good idea. The 2013 AAFP/ISFM environmental needs guidelines give a minimum of two toileting areas as an example of letting a cat choose.
Is the laundry room a good place for a litter box?
A laundry room is often a poor spot for a litter box. VCA's behaviorists say a box in the far recesses of a basement or near a furnace or washing machine may be undesirable, and that a cat may avoid a box in a noisy or busy area. Cornell and the ASPCA both point to quiet spots instead.
Should I punish my cat for going outside the box?
You should never punish a cat for going outside the litter box. Cornell's Feline Health Center says never to hit, kick or scream at a cat for house soiling, because punishment does not work and the anxiety it causes may make the problem worse. See your vet first, then look at the box setup.