Why does my litter box smell? Causes and fixes that actually work

When people say "my house smells like cat," they usually mean the litter box. The good news: the guidance from veterinary sources is consistent, and most of it costs little or nothing.

1. Scooping frequency is the biggest factor

Ohio State's Indoor Pet Initiative says the box "must be scooped daily and washed weekly with mild dish detergent," and adds: "Odor should not be a problem if the litter box is kept clean." The AAFP/ISFM house-soiling guidelines go further. Unless you can remove soiled litter "at least once every 2 h to avoid odor build up," many commercial boxes are too small.

2. The box may be too small

The AAFP/ISFM guidelines recommend a rectangular box 1.5 times the length of the cat from nose to base of tail. See our size guide.

3. A covered box holds odor in

Cornell notes that "from your cat's point of view, covers hold odors in," and OSU says covered boxes "concentrate odors more than uncovered boxes." See covered vs open.

4. Too few boxes

Cornell, OSU and AAHA all give the rule of thumb "one per cat, plus one." See how many boxes.

5. Masking with fragrance

OSU says many cats "are put off by the odor of scented or deodorant litters," and advises against air fresheners near the box. See scented vs unscented.

When to call the vet

If your cat starts going outside the box, or the box suddenly smells very different, OSU notes the cause could be a disease problem. Ask your vet.