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Which Cat Litter Is Best?

Clumping, clay, crystal or plant-based: what veterinary guidelines and cat preference studies say about choosing a litter, how deep to pour it and how to switch.

Choolip Team6 Oct 2026 · 6 min read

Tabby cat stepping into a large open litter box with a shallow layer of fine gray clumping cat litter in a quiet corner by a window

For most cats, the best cat litter is an unscented, fine-grained clumping litter, poured one to two inches deep. Feline veterinary guidelines, Cornell and the ASPCA all point the same way, and studies of what cats choose for themselves keep agreeing.

Your cat still gets the final vote. Below is what each litter type offers, what the research found, and how to switch without a protest on the bath mat.

What kind of litter do cats actually prefer?

Something soft, fine and plain. The AAFP and ISFM guidelines on house-soiling describe the ideal litter as a fine, sand-like, non-scented, clumping material.

The 2021 AAHA/AAFP Feline Life Stage Guidelines agree: most adult cats prefer clumping litter, and most prefer plain, unscented litters. Some cats find scented litters strongly off-putting.

Particle size matters too. A 2019 study in the journal Animals sums up earlier research this way: cats prefer small particles over pellets or pearl-shaped granules, and they find strong perfumes aversive.

Here's the part that explains it. Merck's veterinary manual notes that many cats dig before and after they go, possibly to bury their waste. Kittens start using a litter box or other container of sand-like material between 2 and 7 weeks of age.

A fine, sandy litter is the closest match to that digging and covering, which may be part of why it keeps winning in preference studies.

Does the choice really change anything?

It seems to. A 2023 survey in the Journal of Feline Medicine and Surgery looked at 3,106 cats in Italy and the litter each one used.

Compared with clumping litter, biodegradable litters were linked with 1.31 times the odds of house-soiling. Less common types, such as paper or lentils, were linked with twice the odds.

A survey shows a link rather than a cause, and plenty of cats do well on other litters. Still, it lines up with the guidelines, which is reassuring if you're standing in a long litter aisle.

How do the main types of cat litter compare?

Here is the short version, based on the guidelines and studies above.

Litter type	What it is	What the evidence says
Clumping clay	Fine clay that forms scoopable clumps	The texture the guidelines recommend. The comparison point in the Italian survey.
Non-clumping clay	Clay that soaks up urine without forming clumps	Fine texture, but the guidelines name clumping as the preference.
Silica crystals	Absorbent silica beads or granules	Larger crystals and pearls fall on the wrong side of the particle-size research. Finer versions exist.
Plant-based (corn, wheat, tofu, pine, paper)	Pellets or granules made from plant material	Pellets are the shape cats tend to like least. Biodegradable litters carried higher odds of house-soiling in the survey.
Scented or deodorizing	Any of the above with added fragrance	The AAFP/ISFM guidelines say cats often find aromatic litter and deodorizers offensive.

What if I want an eco-friendly litter?

It can work, especially a fine-grained, clumping plant litter. In a 2022 study, 16 shelter cats were moved from clay to a plant-based clumping litter over six days.

The cats sniffed the new litter more, but urinated and defecated in the boxes just as before. Both Animals studies were funded by a litter maker, which is worth knowing.

If you choose plant-based, pick the finest, softest texture you can find, and make the change slowly.

Does scented litter help with the smell?

For you, maybe. For your cat, probably not. An owner guide in the Journal of Feline Medicine and Surgery notes that many cats dislike aromatic or dusty litters, litter deodorizers and box liners.

The smell people notice comes from waste left sitting in the box. Cornell's advice for clumping litter is to remove feces and clumps every day, and to change the litter often enough that it looks and smells dry and clean.

How often matters more than you'd think. In the Italian survey, cats whose boxes were scooped three times a week had 2.28 times the odds of house-soiling compared with cats whose boxes were scooped twice a day.

The ASPCA recommends scooping at least once a day. Once a week, it suggests washing every box with warm water and unscented soap, baking soda or no soap, and replacing all the litter.

How deep should the litter be?

Shallower than many people pour it. Cornell says most cats prefer litter about one to two inches deep, and the ASPCA recommends one to two inches rather than three to four.

The AAFP/ISFM guidelines suggest at least 1.25 inches (3 cm), and note that cats vary. So somewhere between 1.25 and 2 inches suits most cats, and your cat's digging will tell you if it wants more.

Covered box or open?

The research is split, and that's useful to know. Cornell says most cats prefer an uncovered box, which lets odors escape and gives a 360-degree view.

In a study of 28 cats published in the Journal of Feline Medicine and Surgery, though, there was no overall preference. Four cats preferred covered boxes and four preferred open ones.

The authors concluded that when boxes are cleaned at least once a day, most cats won't mind either style.

How do I switch litters without upsetting my cat?

Slowly. Cornell warns that a cat may dislike its litter after a recent, sudden change of brand. If you need to switch, add small amounts of the new litter to the old.

The 2022 study used a simple schedule: a quarter new litter, then half, then three quarters, then all new, over six days.

You can also let your cat choose. The AAHA/AAFP guidelines suggest offering different litters in separate boxes, side by side, and seeing which one gets used.

A spare box makes this easy. The usual guidance is one box per cat plus one, and our guide to how many litter boxes you need explains where to put them.

Bringing home a kitten? Start with the litter it already knows, and follow our guide to how to litter train a kitten.

Thinking about an automatic box? Check which litter it needs before you buy. Our look at whether a self-cleaning litter box is worth it covers that question.

Call your vet promptly if your cat:

starts going outside the box after using it well
strains, cries or seems uncomfortable in the box
goes much more or much less often than usual
has blood in its urine or stool

A new litter can be the reason a cat avoids its box, but it isn't the only one. Cornell advises a vet visit, with a full physical exam and tests, to rule out a medical cause.

Questions cat parents ask

What is the best cat litter for smell?

An unscented clumping litter, scooped every day. Fragrance can put cats off the box, and daily scooping removes the source of the smell.

Is crystal litter better than clay?

Not for most cats' paws. Research finds cats prefer small particles over pellets and pearl-shaped granules, and the guidelines recommend fine, clumping litter. A fine silica litter is a closer match than large crystals.

What litter is best for a new kitten?

The one it used before coming home. After that, an unscented clumping litter with a fine texture, changed over gradually if you switch.

How often should I change cat litter completely?

The ASPCA suggests replacing all the litter and washing the box once a week. The owner guide gives a range of every one to four weeks for washing, with daily scooping in between.

Sources

This article is for general information and is not veterinary advice. Talk to your vet about your own cat — they know the animal in front of them.

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