How to stop cat litter smell: go after the bacteria living in the used granules. The fresh waste you scoop is rarely the problem. The seven fixes below start with the cheapest.
Why it helps: less time for bacteria to colonize fresh waste before it is removed.
Pro tip: scoop morning and evening, especially in multi-cat households. Add an odor-control product only after the basic maintenance routine is already consistent.
How to do it:
Why: scented litters mask odor temporarily but make smell worse long-term. The perfume mixes with ammonia, creating a worse combination than either alone.
Options worth starting from:
Simple fixes: place the box near (not blocking) an air vent, use a small fan, keep the bathroom door cracked. Fresh air dilutes ammonia concentration.
Why: plastic develops microscopic scratches that harbor bacteria. After 12 to 18 months, a box can't be fully cleaned, and a new one costs a lot less than the smell it prevents.
How it works: activated carbon can help adsorb ammonia and other odor compounds in the litter bed instead of covering them with perfume. If the litter itself is the weak link, start with our Best Cat Litter for Odor Control instead.
Useful when odor is what forces early full-box changes, even after you are already scooping and cleaning consistently.
Adds another recurring product to the setup, so compare the extra cost against how much litter you actually save in your home.
The smell isn't from fresh waste - it's from bacterial colonies that have colonized your litter granules. Even after you scoop solid waste, these bacteria continue producing ammonia from residual urine, the gas the CDC ATSDR says most people can smell above roughly 5 parts per million.
This is why you can scoop daily and still have smell. You're removing waste, not bacteria.
Nearly everyone who lands here has already bought a second bag of something. Before you buy a third, work out which of the three levers your box is actually short on. Start at the top and stop at the first honest "no".
If no: Fix this first and change nothing else for two weeks. It is free, and no bag and nothing you add to the box makes up for waste that stays in it.
If yes: Good. Move to the next question.
If no: Empty it and scrub it with an enzyme cleaner, corners and seams included. Bacteria live on the plastic, not only in the litter, so fresh litter in a dirty box starts smelling early.
If yes: Good. If the box is more than 12 to 18 months old and scratched, replace it anyway - a scratched box cannot be cleaned.
If no: This is a litter problem, and a bag is the fix. Clumps that crumble leave the smell behind, and perfume on top of ammonia reads worse than ammonia on its own. Our odor board ranks the tested picks on both.
If yes: Good. Keep the cat on it. Changing a litter a cat is happy with is the most expensive way to solve a smell.
If no: Then you are done. Nothing else on this page will pay for itself.
If yes: Now an odor-control layer is worth trying, because it is the only lever left. It goes on top of the routine and the litter, never instead of them, and it will not rescue a box that is not being emptied.
The order matters because the cheap levers are also the certain ones. Scooping and a clean box cost nothing and always help. A different litter costs one bag and helps if the current one is the weak link. Anything you add to the box is the last lever, not the first, and it does not carry a box you are not emptying.
Combine these to keep the box genuinely fresh:
Add litter, cleaning supplies, and any optional additive, then divide by the days in the cycle. Compare that to what you spend today before deciding an additive is worth it.
Activated carbon that goes into the litter you already use, so smell gets its own fix instead of a different bag. In our own use it made the biggest difference to litter-box smell of anything we have tried.
Read our Purrify guide to picking a litter for odor control.
This guide is maintained by the ReviewCatLitter editorial team and tied back to the live odor-control review set, category roundups, and the published methodology.