How Often to Change Cat Litter (and How to Clean the Box)
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A litter box that smells is usually a litter box that needs a full change, not just a scoop. This page explains how often to scoop, how often to replace all of the litter for each type of litter, how to wash the box, and the changes in your cat’s litter habits that mean it is time to call the vet.
The short answer: scoop at least once a day, and empty the box completely, wash it and refill it with fresh litter about once a week. The ASPCA gives that weekly schedule for all boxes. Some clumping clay makers say a full change every three to four weeks is enough if you scoop every day, but more cats, a smaller box or a box that still smells after scooping all mean changing it sooner.
How we wrote this: the advice on this page comes from the ASPCA, the Cornell Feline Health Center, the CDC and litter brands’ own care pages, each linked where it is used. We have not tested these products ourselves. If your cat strains in the box or passes little or no urine, see a vet right away.
How often to change cat litter at a glance
| Task | How often | Source |
|---|---|---|
| Scoop waste and clumps | At least once a day | ASPCA, Cornell |
| Replace all litter and wash the box | About once a week | ASPCA |
| Full change, hard clumping clay with daily scooping | Every 3 to 4 weeks, depending on use | Dr. Elsey’s |
| Full change, crystal litter | Every few weeks to once a month, depending on the number of cats | PetSafe |
| Full change, pine or non-clumping clay | At least once a week | PetSafe |
| Full change, paper litter | Every few days | PetSafe |
Scoop every day
Daily scooping is the one habit every source agrees on. The ASPCA says to scoop at least once a day, and the Cornell Feline Health Center says that with clumping litter you should remove feces and clumps daily and add clean litter as needed. Cats are clean animals, and a dirty box is one of the common reasons a cat starts to go elsewhere in the house.
There is also a health reason. 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 whether someone else should handle the litter box, and wash your hands after every scoop.
A sturdy scoop with the right slot size makes daily scooping faster. A metal scoop such as the DuraScoop Jumbo will not bend or crack the way a thin plastic one can, and a sealed pail like the Litter Genie saves a trip to the outside bin each day.
How often to replace all the litter
Scooping removes most of the waste, but not all of it. Small pieces of urine-soaked litter and feces break off and stay behind, so the litter that is left slowly gets dirtier. Litter maker Dr. Elsey’s explains this even for its own hard-clumping clay and recommends changing all of the litter every three to four weeks, depending on use.
The ASPCA is stricter: once a week, clean all litter boxes and completely replace the litter. Cornell puts it in practical terms: change the litter often enough that it looks and smells dry and clean, and more often the more cats use the box. A good rule is to start with a weekly change and stretch it only if the box still looks and smells clean at the end of the week.
By litter type
Different litters hold waste in different ways, so they last for different lengths of time. Our guide to the types of cat litter compares them in detail. Here is how PetSafe, which makes litter boxes for several litter types, times a full change:
- Clumping clay such as Dr. Elsey’s Ultra or Arm & Hammer Clump & Seal: PetSafe says at least once a week. Dr. Elsey’s says every three to four weeks with daily scooping. Weekly is the safe choice for a busy box.
- Non-clumping clay: needs changing more often than clumping litter, at least once a week, because urine soaks into the litter instead of forming a clump you can remove.
- Crystal (silica) such as Fresh Step Crystal: every few weeks to once a month, depending on how many cats share the box. Stir it daily so the crystals absorb evenly.
- Pine pellets such as Feline Pine: at least once a week. The pellets break down into sawdust as they absorb urine, so sift the sawdust out between changes.
- Corn and other plant litters such as World’s Best: these clump, so treat them like clumping litter. Scoop daily and replace all of it when the box starts to smell between scoops.
- Paper: every few days, since paper pellets hold less before they become soggy.
Signs it is time for a full change
- The box smells soon after you scoop.
- Clumps break apart when you lift them, or the litter looks wet or dark.
- Pellets have turned mostly to sawdust, or crystals have turned yellow.
- The litter is shallower than one to two inches after scooping.
- Your cat sniffs the box and leaves, or starts going just outside it.
How to wash the litter box
Each time you replace all the litter, wash the empty box. The ASPCA suggests warm water and unscented soap, baking soda or no soap at all. Dr. Elsey’s suggests hot water and a mild dish soap. Avoid strong-smelling cleaners: a box that smells of bleach or citrus can put a cat off using it.
- Tip the old litter into a bag and tie it closed.
- Rinse the box, then wash it with warm water and unscented soap or baking soda.
- Rinse well so no soap smell is left, and dry it completely.
- Refill with fresh litter. The ASPCA says most cats like one to two inches rather than three to four.
A box with a smooth, hard surface is easier to keep clean. Plastic scratches over time, and scratches hold smell, so replace a box that still smells after washing. Some designs, such as the Omega Paw Roll ‘n Clean, separate clumps when you roll the box, but they still need a full change and wash.
More cats means more changes
The ASPCA recommends one litter box for each cat plus one extra. Sharing boxes means each one fills faster, so with two or more cats, scoop twice a day if you can and plan on a weekly full change for every box. Spreading the boxes around the home also helps. Our best litter box for multiple cats page covers sizes and layouts, and best cat litter for odor control covers litters that hold up in a busy box.
When litter box changes mean a vet visit
Changes in how your cat uses the box can be the first sign of illness. The Cornell Feline Health Center lists the signs of lower urinary tract disease: difficult or painful urination, going more often, crying out while urinating, blood in the urine and urinating outside the box. Cornell also notes that kidney disease, thyroid disease and diabetes often make cats drink and urinate more, so bigger or more clumps than usual are worth mentioning to your vet.
The most urgent sign is a cat, especially a male, that strains and passes little or no urine. Cornell calls urethral obstruction a true medical emergency: a blocked cat can die within a day or two. Take your cat to a vet at once.
Mistakes to avoid
- Topping up instead of changing: adding fresh litter on top hides the smell for a day but leaves the old waste underneath.
- Too much litter: a deep box wastes litter and many cats prefer one to two inches.
- Scented cleaners and sprays: strong smells can make a cat avoid the box.
- Waiting for a smell: by the time you can smell the box from the next room, your cat has been putting up with it for days.
- Flushing litter: most litters can clog pipes, so bag used litter and put it in the trash. Check the bag before flushing any litter labelled flushable, and check your local rules.
FAQ
How often should you completely change cat litter?
About once a week for most homes, which is the ASPCA’s advice. With a hard-clumping clay litter, one cat and daily scooping, some makers say every three to four weeks is enough. Change it sooner if the box smells after scooping.
How often should you scoop the litter box?
At least once a day, and twice a day with more than one cat. Daily scooping also matters for health: the CDC notes that the Toxoplasma parasite takes one to five days to become infectious after it is shed.
How often should you change litter with two cats?
Give each cat its own box plus one extra, scoop every box daily and replace all the litter about once a week. Shared boxes fill faster, so they may need it even sooner.
How often should you change crystal cat litter?
PetSafe says every few weeks to once a month, depending on how many cats use the box. Scoop solids daily and stir the crystals so they absorb evenly.
Can you just add more litter instead of changing it?
Only to top it up to one to two inches after scooping. Small bits of waste stay behind each time you scoop, so the whole box still needs a full change and wash regularly.