When a Cat Pees Outside the Litter Box: What to Check

Q: Should I take my cat to the vet first?

Yes. The ASPCA page says the first step is to rule out urine marking and medical problems, and to have your cat checked thoroughly by a veterinarian. Cornell says the same about a cat that is house soiling.

Q: How many litter boxes do I need?

Cornell says to keep as many litter boxes as cats in the house, plus one. A two-cat home needs three boxes.

Q: What is urine marking, and how is it different?

The ASPCA page says a marking cat regularly eliminates in her litter box but also deposits urine in other locations, usually on vertical surfaces, in small amounts. Marking is considered a rule out, so the vet should check it.

Q: How should I clean the spot?

Cornell says the spot must be neutralized, not just deodorized, and says to avoid ammonia or vinegar because they smell like urine. Clean the spot soon after it is soiled.

As an Amazon Associate we earn from qualifying purchases. Details

Short answer: Have a vet rule out medical causes first, then check the box, the spot it sits in, and whether the cat is marking.

The person typing “cat peeing outside litter box” wants to know why the cat is doing it and what to check first. The sources below list the usual causes. They do not diagnose any one cat, and they do not give a fix that works in every home. This page is for information only and is not veterinary advice.

At a glance: box checklist, sourced from ASPCA and Cornell

Check	Guidance	Source
Cleaning frequency	Scoop at least once a day	ASPCA
Number of boxes	One box per cat, plus one extra	ASPCA
Box size	Most cats prefer large boxes they can enter easily	ASPCA
Litter depth	1 to 2 inches	ASPCA
Hoods/liners	Most cats do not like box liners or lids	ASPCA
Box sides	Low sides for kittens and cats with joint pain	Cornell
Box location	Quiet, private, separate from feeding area, accessible 24 hours	Cornell
Multi-cat households	Multiple boxes in multiple locations (spacing not specified)	Cornell
Urine marking rate	10% of neutered males, 5% of neutered females still spray	Cornell
Cleaning product to avoid	No ammonia or vinegar-based cleaners	Cornell

Quick answer

The ASPCA says: “The first step in resolving elimination outside the litter box is to rule out urine marking and medical problems. Have your cat checked thoroughly by a veterinarian.”
Cornell says most cats prefer a spot that is “quiet, private, separate from their feeding area, and easily accessible 24 hours a day.”
Cornell says to “Keep as many litter boxes as cats in the house – plus one.”
Cornell says “Many cats object to foul odors, so clean the box regularly and use a non-scented litter.”

Start with a vet check

Cornell’s house soiling page says a cat that is house soiling should be taken to a veterinarian “for a thorough physical examination and appropriate diagnostic tests.” The page lists medical problems as a common reason a cat stops using the box, including urinary tract inflammation, kidney and thyroid disease, and diabetes. Those are causes the page names, not a diagnosis for your cat.

The ASPCA page gives one sign to report. If a cat “frequently enters her litter box and seems to produce only small amounts of urine,” the page says to see a veterinarian to rule out a urinary tract infection. Any sign of pain, straining or frequent trips to the box is a reason to call the vet now, not after you change the box.

Check the box

Most of the box-side causes in these sources are about comfort and cleanliness. The ASPCA page lists these common reasons a cat may pee outside the box:

The box is not cleaned often or thoroughly enough. The page says cats like clean boxes and should have the litter scooped at least once a day.
There are too few boxes. The page says to have “a litter box for each of your cats, as well as one extra.”
The box is too small. The page says the majority of cats prefer large boxes that they can enter easily.
The litter is too deep. The page says cats usually prefer “one to two inches of litter.”
The box has a hood or a liner. The page says most cats do not like box liners or lids.

Cornell’s house soiling page says some cats refuse a box with urine or feces in it, so the box has to be clean before you judge it.

Low sides matter for some cats. Cornell says “Small kittens and cats with joint pain need a box with low sides.” The ASPCA page says cats with physical limitations may find top-entry boxes or high-sided boxes hard to use.

Check the spot

Cornell’s house soiling page says most cats prefer a location that is “quiet, private, separate from their feeding area, and easily accessible 24 hours a day.” The Choosing and Caring page says a new cat needs “separate food and water dishes, kept far away from the litter box.” The ASPCA page says cats like a spot that is “quiet but not ‘cornered,'” with more than one escape route.

If the cat used to use the box and then stopped, the spot may have changed. Cornell says to try a box “in her ‘preferred’ location,” and then move the box back in small steps: “gradually move the box just a few inches a day.” It also says to “Stop moving the box if she stops using it.”

In a home with more than one cat, Cornell says to “place multiple boxes in multiple locations to give your cat more options.” The sources do not say how far apart the boxes should be.

Check for urine marking

Urine marking looks different from a litter box problem. The ASPCA page says a cat that marks “will regularly eliminate in her litter box, but will also deposit urine in other locations, usually on vertical surfaces.” The amount is usually small, and the page says marking is “considered a rule out,” which means check it before anything else.

Cornell says “Cats that spray are usually unneutered males and, to a lesser extent, unspayed females, but 10% of neutered males and 5% of neutered females also spray.” Neutering does not rule out marking, so a vet should review it.

Clean the soiled spot

Cornell says the spot needs to be neutralized, not just covered. The page says “odors must be neutralized, not just deodorized, to escape a cat’s keen sense of smell.” It also says to avoid “cleaning products containing ammonia or vinegar as they smell like urine and can be irritating.”

If you use a self-cleaning box and the cat starts to pee outside it, the ASPCA page says to “try switching to a traditional type of litter box.” See our guide to self-cleaning cat litter boxes before you buy one.

How we chose

On 2026-10-19 we opened three pages with curl: the Cornell house soiling page, the Cornell Choosing and Caring for Your New Cat page, and the ASPCA Litter Box Problems page. We checked each quote against the page text. We did not rank products for this topic, and this page names no product. This is not a ranking.

What we could not verify

The sources do not say how to tell, for one cat, whether the cause is medical, marking, or a box problem. A vet makes that call.
The sources do not give room sizes or distances for box placement.
The sources do not say how long a cat takes to return to a box after a change.

Checklist

Book a vet visit and tell the vet where and how often the cat pees outside the box.
Count the cats and add one. Cornell says “plus one.”
Check that each box is large, has low enough sides for the cat, and has one to two inches of litter.
Check that each box is in a quiet spot, away from food and water, with more than one way out.
Scoop daily, and clean the soiled spot with a neutralizer rather than ammonia or vinegar.
Note any urine on vertical surfaces. The ASPCA page says that pattern may be marking, and the vet should review it.

Mistakes to avoid

Changing the box before the vet visit. The ASPCA page says the first step is to rule out marking and medical problems.
Cleaning with ammonia or vinegar. Cornell says they “smell like urine.”
Putting the box next to the food bowls. Cornell says the dishes should be kept far from the box.
Using one box for two cats. Cornell says to keep as many boxes as cats, plus one.
Punishing the cat. Cornell says you “should never hit, kick, or scream at a cat,” and that punishment can make the problem worse.

FAQ

Why is my cat peeing outside the litter box?

The sources list several causes: medical problems, a dislike of the box, the litter or the spot, and urine marking. They do not say which one applies to your cat. A vet can help rule out medical causes, and the box checks above can rule out the box and the spot.

Should I take my cat to the vet first?

Yes. The ASPCA page says the first step is to “rule out urine marking and medical problems,” and to “Have your cat checked thoroughly by a veterinarian.” Cornell says the same about a cat that is house soiling.

How many litter boxes do I need?

Cornell says to “Keep as many litter boxes as cats in the house – plus one.” A two-cat home needs three boxes, and the sources do not say which rooms they should be in.

What is urine marking, and how is it different?

The ASPCA page says a marking cat “will regularly eliminate in her litter box, but will also deposit urine in other locations, usually on vertical surfaces,” in small amounts. Marking is “considered a rule out,” so the vet should check it.

How should I clean the spot?

Cornell says the spot must be “neutralized, not just deodorized,” and says to avoid ammonia or vinegar because they “smell like urine.” Clean the spot soon after it is soiled, because cats will return to a spot that still smells of urine.

Bottom line

When a cat pees outside the box, have a vet rule out medical causes and marking first. Then check the box size, the litter depth, the number of boxes and the spot. Clean the soiled area with a neutralizer, and do not punish the cat.

For the rest of the setup, see our guides to litter boxes for small apartments for room planning, self-cleaning cat litter boxes if you want less daily cleaning, the Litter-Robot 4 review for a fully automatic model, and cat trees for small apartments for vertical space away from the box. If you are moving food and water away from the box, see automatic cat feeders and cat water fountains. For play and perching, see interactive toys for indoor cats and window perches.

Sources

Cornell Feline Health Center, Feline Behavior Problems: House Soiling: https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-behavior-problems-house-soiling (opened 2026-10-19). Cited for placement, box count, stairs, moving the box, cleaning, medical causes and the veterinary check.
Cornell Feline Health Center, Choosing and Caring for Your New Cat: https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/choosing-and-caring-your-new-cat (opened 2026-10-19). Cited for box count, low sides, and food and water dishes kept away from the box.
ASPCA, Litter Box Problems: https://www.aspca.org/pet-care/cat-care/common-cat-behavior-issues/litter-box-problems (opened 2026-10-19). Cited for the first-step guidance, urine marking, litter depth, liners, self-cleaning boxes and the veterinary check.

Disclosure: As an Amazon Associate we earn from qualifying purchases. The content is general information, not veterinary advice. Read our affiliate disclosure.