Litter Box Hygiene Guide

Litter box smell is a routine problem before it is a product problem. The Cornell Feline Health Center’s advice comes down to this: as many boxes as there are cats, plus one, an inch or two of unscented litter, feces and clumps out every day, and the box itself washed regularly. Get those right and there is little left for a deodorizer to do.

This guide follows two sources throughout - that Cornell page and the ASPCA’s page on litter box problems.

How Many Boxes

Both sources give the same rule: one box for each cat, plus one extra. The ASPCA spells it out - three cats need a minimum of four boxes.

1 cat: 2 boxes
2 cats: 3 boxes
3 cats: 4 boxes

Cornell’s reason is competition: with enough boxes, each cat can always reach one. Put them in different places rather than in a row, and on a floor your cat can reach easily if it is old or stiff.

The Daily and Weekly Routine

Every day

Scoop. Cornell: with clumping litter, remove feces and clumps daily and add clean litter as needed. The ASPCA says to scoop at least once a day.
Sweep up tracked litter around the box.

Regularly

Wash the box. Cornell says to wash boxes regularly with a gentle detergent. The ASPCA’s version is more specific: rinse the box out completely with baking soda or unscented soap once a week, and replace the litter.
Change all the litter often enough that it looks and smells dry and clean. With several cats that means more often.

Why daily matters for you, too

The CDC advises changing the litter box daily because the Toxoplasma parasite does not become infectious until one to five days after a cat sheds it in its feces. If you are pregnant or have a weakened immune system, ask your doctor who should be doing this job.

Litter Depth and Type

More litter is not better. The ASPCA advises one to two inches of litter rather than three to four, and Cornell describes what cats prefer as unscented, finer-textured litter about one to two inches deep. The ASPCA adds that most cats prefer clumping, unscented litter.

For the differences between clay, crystal, wood, corn and paper, see Cat Litter Types Compared.

The Box Itself

Size. Cornell notes that larger and overweight cats need bigger boxes. If your cat hangs over the edge or cannot turn round, the box is too small - a large storage tub is a common substitute for a Maine Coon or another big cat.

Sides. Young kittens, elderly cats and cats with mobility problems need low sides.

Lid. Cornell says most cats favor uncovered boxes, because covers hold odors in and an open box gives the cat a view all round. The ASPCA says most cats do not like liners or lids. If you want a covered box, offer an open one as well and see which the cat chooses.

Where. Quiet, private, away from the feeding area, and reachable at any hour.

Material. Most boxes are plastic. Plastic scratches with use, and a scratched box is harder to get clean; replace one that still smells after washing. Stainless steel boxes cost more and are sold as the longer-lasting alternative.

Five litter boxes compared

Box	Type	Size (L x W x H)	What the maker states	Links
Modkat Tray	Open, high-sided	20.3 x 14.0 x 9.0 in; 15.75 in with splash guard	Splash guard for cats that pee high; walk-off platform; reusable liner lasts up to 3 months	See on Amazon · Maker’s page
Tuft + Paw Cubby	Open, with removable 8” walls	See the maker’s page	Semi-transparent sides so the cat can watch its surroundings; anti-stick, odor-resistant plastic	See on Amazon · Maker’s page
Modkat Flip	Covered, front entry	20.5 x 15.75 x 16.8 in; entry 6.75 in from the floor	Magnetic three-position lid; replaceable charcoal odor filters; front step to hold litter in	See on Amazon · Maker’s page
Modkat XL	Covered, top or front entry	21.0 x 16.5 x 17.0 in; top entry 10.25 in wide	”Largest top-entry litter box” by the maker’s account; top, front or dual entry; seamless base	See on Amazon · Maker’s page
Tuft + Paw Cove	Open, with removable walls	See the maker’s page	Built-in scoop, dustpan and brush; compact for small spaces	See on Amazon · Maker’s page

How we put this together. Five widely sold boxes from two makers, three open and two covered, compared on what each maker states on its own product page, checked on 26 October 2026. Cornell’s advice above still applies: most cats favor uncovered boxes, so if you buy a covered one, offer an open one too and let the cat choose. Cornell’s call for low sides for kittens, elderly cats and cats with mobility problems matters here too, because a top-entry box means climbing in from above. We have not tried these boxes. There are no prices here: the Amazon links search for the exact product, and we may earn a commission if you buy through them.

Litter Mats

A mat in front of the box catches some of the litter that leaves on the cat’s paws.

Deodorizers and Scent

Scented products are aimed at people, and they can work against you. Cornell and the ASPCA both describe unscented litter as what cats prefer, and the ASPCA warns that a cat can develop an aversion to the smell of a scented cleaner - a cat that dislikes the smell of its box may stop using it.

So, in order:

Scoop every day.
Wash the box with unscented soap or baking soda.
Change the litter before it smells.
Air the room.

A spray or powder on top of a dirty box only adds a second smell.

When the Smell Will Not Go

Right after scooping: the litter is saturated. Change all of it and wash the box.
After a full change: the box itself may be holding odor. Replace it.
Around the box, not in it: lift the box and check the floor and the wall behind it. For cleaning urine out of floors and carpet, see our pet odor remover guide.
A sudden change in smell, or in how often the cat goes: call the vet. Cornell lists inflammation of the urinary tract, kidney disease, thyroid disease, diabetes and digestive problems among the medical causes of litter box trouble.

Self-Cleaning Boxes

A self-cleaning box sifts after each visit and stores the waste in a closed drawer. It reduces scooping; it does not remove the need to empty, wash and watch.

Special Cases

Kittens. A shallow, open box with low sides. The ASPCA’s foster care guide specifies non-clumping litter for young kittens learning to use a box.

Old or arthritic cats. Low sides, and a box on the floor where the cat spends its time.

After surgery. Use the litter your vet tells you to.

Several cats, one of them pushy. Spread the boxes out so that no cat can guard them all, with at least one where a nervous cat cannot be cornered.

Frequently Asked Questions

How often should I scoop?

At least once a day, according to both Cornell and the ASPCA.

How often should I change all the litter?

Often enough that it looks and smells dry and clean. The ASPCA suggests a full change and a rinse of the box once a week.

Are covered boxes better for smell?

For the room, perhaps. Cornell’s point is that covers hold odors in, which is why most cats favor an open box.

How many litter boxes do I need?

One per cat, plus one.

My cat suddenly stopped using the box. What is wrong?

See the vet first, to rule out a medical cause. Then look at what changed: the litter, the cleaner, the location, another animal in the house.

Are scented litters a problem?

Cats generally prefer unscented litter, and a scent the cat dislikes can put it off the box.

Can I wash the box with baking soda?

Yes - the ASPCA suggests baking soda or unscented soap.

Do self-cleaning boxes solve the problem?

They cut down the scooping. The box still has to be emptied and washed, and some cats refuse them.

Final Word

Enough boxes, a shallow layer of unscented litter, a daily scoop and a regular wash. That is the whole system, and it is the one the veterinary sources describe. Mats, steel boxes and automatic boxes are conveniences on top of it.

Cat Litter Types Compared
Pet Odor Removers: Enzyme Cleaners and How to Use Them Last updated: October 2026.