Tidy Cats Designed for Litter-Robot is the litter to buy for a Litter-Robot. Purina made it for the globe, so the clumps set fast and stay whole while it turns, instead of smearing on the liner, and it's one of the two litters Whisker, the maker of the Litter-Robot, names as the best for its boxes. A 22-pound box costs just under $20.
It is scented, though. The scent comes out each time the globe turns, and a cat who walks away from perfumed litter needs an unscented clay instead. If your robot isn't a Litter-Robot, the table after the picks gives the litter each of the other boxes takes.
You own a Litter-Robot, any model, and you want the litter made for it at grocery-store prices.
Skip it if
Your cat sniffs and leaves when a litter smells of anything. Take BoxiePro Bot, which has no fragrance at all.
Purina built it for the Litter-Robot 4 and the models before it, and tuned it for The Perfect Cycle, a setting in the Whisker app. The clumps form hard and fast, so they hold together through the turn and drop into the drawer in one piece, and an odor absorber works in the drawer itself, which is where a robot's smell sits between emptyings.
Whisker's other favorite, its own Lit, is sold by Whisker and not on Amazon, which leaves this one as the maker's pick you can order with the rest of your cat's things. Next to BoxiePro Bot, you pay less by the pound and get a bigger box; what you give up is the unscented litter, which Whisker itself writes that most cats prefer.
Where it falls short
It's scented, and the scent is released every time the globe turns.
Made with the Litter-Robot in mind. CATLINK, for one, prefers an unscented clay in its Open-X.
2Best unscented
2. BoxiePro Bot
Clay made for automatic boxes, with no fragrance: probiotics go after the bacteria that make the smell.
Your cat avoids perfumed litter, or your robot isn't a Litter-Robot.
Skip it if
You buy litter on price. It's the dearest clay of the five by the pound.
For a cat who won't go near a scent, this is the robot litter to buy: Boxie makes it for automatic boxes, with no fragrance, and it's on Whisker's list of litters that work in a Litter-Robot. The grain is fine but firm, made to keep clumps off the drum and dust off the sensors, so it also suits the PetPivot, which asks for a small-grain clay, and the CATLINK Open-X, which takes clay only.
Where it falls short
It comes in a 16-pound bag, so with two cats you're reordering often.
Read more about the BoxiePro BotShow less
Instead of perfume, it carries probiotics, which Boxie puts to work on the bacteria that make the smell rather than covering it up. For a kitten, Boxie's advice is to wait until 12 weeks before any clumping clay, and every robot has its own minimum on top of that.
What owners report
Of the owners who moved to it from Boxie's regular clay, one says the robot stays cleaner, and another sees no difference in a Litter-Robot 4 and minds paying for 16-pound bags.
3Cheapest by the pound
3. Dr. Elsey's Ultra
Plain unscented clay that clumps hard, at the lowest price per pound of the five.
Two or three cats share one robot, and the price per pound decides.
Skip it if
Your box is a PetPivot. It asks for a small-grain clay, and the Ultra's grain is medium.
Dr. Elsey's clay is on the list of litters that work in a Litter-Robot, and the Ultra is the cheapest of the five by the pound, by a wide margin. It has no scent and nothing added, it clumps hard, and in the globe you pour it up to the fill line like any other clay. The best cat litter guide has the rest of what it does in an ordinary box.
Where it falls short
Medium grain, too coarse for the PetPivot's small-grain rule.
Read more about the UltraShow less
It has no odor additive of its own, where the Tidy Cats carries one for the drawer.
4Best plant-based
4. Sustainably Yours Large-Grain
Corn and cassava in a large grain, a plant litter that sifts in a Litter-Robot, with no added scent.
You want a plant litter in a Litter-Robot, or you have a HomerunPet, which takes cassava.
Skip it if
Your box is a PetPivot or a CATLINK Open-X. Both ask for clay.
Most plant litters are on the wrong side of Whisker's list, so this is the one to get if you want corn instead of clay in a Litter-Robot: it's made of corn and cassava only, and Whisker points owners to the large grain to keep tracking down. The bigger grains stay in the box better, and the maker credits the starch in both plants for its firm clumps.
Where it falls short
The priciest clumping litter of the five by the pound, in 10-pound bags.
Read more about the Sustainably YoursShow less
There's no fragrance and no dye, and the light color lets you see a change in the color of your cat's urine, a point Sustainably Yours makes for it.
5For a ScoopFree
5. PetSafe ScoopFree Premium Crystal
Loose silica crystals to refill a ScoopFree's reusable tray, instead of buying the disposable ones.
Your robot is a PetSafe ScoopFree and you refill a reusable tray.
Skip it if
Your robot is a Litter-Robot 4 or an EVO. White crystals throw off their sensors.
A ScoopFree runs on crystals, not clumps, and these are the loose ones to pour into its reusable tray, for less than the disposable trays (the ScoopFree's card gives what each costs a month). The crystals soak up urine and dry out the solids, which the rake sweeps into its covered trap.
Where it falls short
All of it goes out every week, where a clumping litter is only topped up.
Read more about the ScoopFree crystalsShow less
Keep them for the ScoopFree: in a Litter-Robot 4, 5 or EVO, white crystals fool the sensors (the question on crystals, below, says how).
BoxiePro Bot fits every box but the ScoopFree. The Tidy Cats is built for the Litter-Robot, and the Ultra suits the clay boxes except the PetPivot. CATLINK keeps lightweight litter out because it misleads the weight sensor, and the Litter-Robot 4, which weighs each cat too, wants a standard-weight litter.
Litters to keep out of a Litter-Robot
Whisker's do-not-use list has a reason for each one, and the reasons come down to three:
They don't sift. Pellets of pine, wood, paper or pea husk sit on the screen instead of passing through it: Feline Pine, ökocat, Yesterday's News, Catit Pea Husk and Tidy Cats Breeze. Tuft & Paw's long tofu strips do the same.
They don't clump. A non-clumping clay like Skoon soaks up urine and stays in the bed, so the globe never takes it away. Olive pits from Paco and Pepper clump loosely and leave residue on the liner.
They fool the sensors or the drawer. White crystals like PrettyLitter confuse the Litter-Robot 4, 5 and EVO. Catalyst is so fine that clean litter falls into the drawer with the waste, and in a Litter-Robot, World's Best, made of corn, comes with reports of smell, damaged drawer and pinch sensors, mold and bugs. Those reports come from the globe: in an ordinary box, it's the plant litter I'd buy.
Tofu works in a Litter-Robot depending on the brand, its clumping and the size of its pieces; long strips like Tuft & Paw's don't sift. Corn splits too: Arm & Hammer Naturals works, with more frequent full changes, and World's Best is on the do-not-use list. Walnut works only in its clumping version, Naturally Fresh's clumping bags rather than its pellets. For a robot built around plant litter, the HomerunPet takes tofu and cassava by design.
How much litter goes in a Litter-Robot
Up to the fill line inside the globe, or just under it, not to the brim. On the Litter-Robot 4 and 5, the LitterHopper add-on (about $129) holds 13 to 17 cups and tops up the bed on its own, over two weeks for one cat.
The wait before each cycle can be set to 3, 7, 15, 25 or 30 minutes on the Litter-Robot 4, 5 and EVO. With a litter that clumps hard and fast, the 3-minute setting is enough; if clumps still break up in the turn, give it a longer wait.
What to look for in a litter for an automatic box
Clumps that set fast
The robot cycles minutes after your cat leaves. A clump still soft by then smears on the liner.
A grain that suits the screen
Too coarse and it stays on the screen, too fine and clean litter ends up in the drawer.
Nothing that fools the sensors
White crystals, lightweight clay, or a dusty litter that coats the sensors.
Odor control without heavy perfume
The drawer holds a week of waste. An odor absorber helps; a strong scent can send your cat elsewhere.
The robot litters I'd leave on the shelf
Lit Premium Cat Litter
Whisker's own litter, a single-ingredient bentonite clay dried in the sun, and its first pick for the Litter-Robot. It's sold by Whisker on its own site, not on Amazon, and the Tidy Cats is the other litter Whisker names first.
Corn with baking soda, and on Whisker's list of litters that work, but it needs full changes more often, and it's sold as 50 percent lighter than clay, the kind of litter CATLINK keeps out of its weighing box. Sustainably Yours is the plant litter to pick.
A clumping wood litter so fine that clean litter goes through the screen into the drawer with the waste.
Also compared: Tuft & Paw Really Great Cat Litter and PrettyLitter. World's Best Multiple Cat, ökocat Super Soft and Tidy Cats LightWeight Free & Clean are all ranked in the best cat litter.
How I picked
On Whisker's list of litters that work, or made for automatic boxesClumps that set within minutesA grain that siftsScent named on the bagPrice per pound
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Common questions
What litter does the Litter-Robot recommend?+−
Whisker names two first: its own Lit Premium, sold on its site, and Tidy Cats Designed for Litter-Robot, sold in stores and on Amazon. Any clumping clay works too, Dr. Elsey's and Fresh Step among them.
Do you need special cat litter for an automatic litter box?+−
No, but you need the right kind: a litter that clumps, for every robot except the ScoopFree, which runs on crystals. A litter sold for robots, like BoxiePro Bot, just makes it easier to get right in any of them.
Can you use tuft and paw litter in a Litter-Robot?+−
Not the Really Great Cat Litter: its long tofu strips don't sift, and Whisker lists it among the litters not to use. Some other tofu litters with smaller pieces work.
Can you use crystal litter in a Litter-Robot 4?+−
It's not a good idea. Crystals small enough to pass the screen will sift, but white or see-through litter throws off the sensors that read the litter level and the full drawer on the Litter-Robot 4, the 5 and the EVO. Save crystals for a ScoopFree.
The verdict
Turn on The Perfect Cycle
If your robot is a Litter-Robot 4, get the Tidy Cats and switch on The Perfect Cycle in the Whisker app the day the box arrives: that's the setting Purina made the litter for.
