Cats are conservative about bathrooms. Change the box, the litter, or the location and a percentage of cats will simply stop using it — not out of spite, but because the thing they had a reliable routine around has changed. The good news is the failure modes are predictable, and so is the fix.
Rule one: never remove the old box first
The single most common mistake is swapping boxes overnight. Put the new box next to the old one and leave both available for at least a week. Your cat gets to investigate the new one with no pressure and no consequence for ignoring it.
Once you see them using the new box consistently for several days, start reducing the old one — move it a few feet away each day, then remove it. If accidents start, you moved too fast. Go back a step.
Rule two: keep the litter identical
Change one variable at a time. New box, same litter. New litter, same box. Changing both at once is how you end up with a cat who has decided the bathroom is now the laundry basket.
If you're also switching litter, do it by mixing: 25% new litter for a week, then 50%, then 75%, then all new. Cats notice texture underfoot far more than they notice brand.
Rule three: get the size and depth right
The box should be about 1.5 times your cat's body length, nose to tail base. Most commercial boxes are too small for an adult cat, which is why so many cats hang their back end over the edge — they're not being difficult, they physically don't fit.
Depth matters too. Two to three inches of litter is the sweet spot. Less and they can't dig properly; more and it gets unstable underfoot, which many cats dislike.
Covered vs. open
Cats generally prefer open boxes. Covers trap odor inside, which is unpleasant for the animal standing in it, and they eliminate escape routes, which matters in a multi-cat house where one cat may ambush another at the box — adding cat trees and perches nearby gives the more nervous cat somewhere to retreat to.
Covered and enclosed boxes exist mostly for human benefit — smell and appearance. That's a legitimate reason to want one, but introduce it slowly and take the door off for the first two weeks if it has one.
Automatic litter boxes: a longer runway
Self-cleaning boxes are excellent once a cat accepts them, and they take longer to introduce because of the noise and movement. Run it in manual mode — cleaning cycle disabled — for the first week or two so the box is simply a box. Only once your cat is using it reliably should you enable the automatic cycle, and never let it run while they're in the room the first few times.
Skittish cats sometimes never accept one. That's worth knowing before you buy.
Troubleshooting: they've stopped using the box entirely
First, rule out medical. Sudden litter box avoidance in a previously reliable cat is one of the most common early signs of a urinary tract infection, crystals, or a blockage. In male cats a blockage is a genuine emergency. Call the vet before you troubleshoot the box.
Once medical is ruled out:
- Is it clean enough? Scoop daily. Cats have a much lower tolerance for a dirty box than most owners assume.
- How many boxes? The standard guidance is one box per cat, plus one. Two cats means three boxes. This is about resource competition, not volume.
- Where is it? Not next to a washing machine, not in a high-traffic hallway, not somewhere with only one way in. Cats want a quiet spot with sightlines — the same logic behind the safe room in our guide to bringing home a new cat.
- Did you change the litter? Even a formula change from the same brand can trigger it. Scented litters are a frequent culprit — the smell that reads as "fresh" to you reads as "strong chemical" to an animal with fourteen times your olfactory receptors.
- Is something new nearby? A new appliance, a new rug, a moved piece of furniture. Cats notice.
Cleaning up so it doesn't repeat
Regular cleaners don't remove the proteins in cat urine — they just remove the smell you can detect. The cat can still smell it, and a marked spot invites re-marking. Use an enzymatic cleaner specifically, and be generous with it.
A double-layer litter-trapping mat under and in front of the box handles the tracking problem, which is a separate issue but usually the next thing people ask about.
The short version
Introduce slowly, side by side. Change one thing at a time. Size the box properly. Scoop daily. And if a reliable cat suddenly stops, call the vet first — the box is usually not the actual problem.
Everything mentioned here lives in our Home & Cleanup and Cats collections, and if you're setting up for a brand new cat, the Kits & Bundles collection covers the full litter setup in one place.