How the checker decides
For each box we compare your answers with the maker's published limits in our comparison data:
- Under the minimum weight or age: not safe in automatic mode. The sensors may not register a light cat, so a cycle could start with the cat inside. Use the box with cleaning off until your cat qualifies.
- No published minimum: we flag it, and treat it as unsafe for cats under 5 lb.
- Over the maximum weight: not a fit. Within 2 lb of the maximum, we warn that it may be tight.
- Big or long cats (15 lb+ or 18 in+ nose to tail base) and an entry under 9 in on either side: a caution. WIRED's 17 lb cat found the PuraMax 2's 7.87 in-tall opening cramped. This is our rule of thumb, not a maker figure.
- More cats than the rating: a caution for one over, unsafe for two or more over. If the maker gives no number and you have three or more cats, we flag it.
- Entrance during the cycle: we flag designs that can close or trap a cat, and note when we couldn't confirm either way.
- Mobility: boxes that sit 10 in or more off the floor get a caution for stiff or senior cats.
Kittens under the minimum should use the box with automatic cleaning off. Check your own cat in the safety checker.
Minimum weights at a glance
| Box | Type | Cat weight | Kittens |
|---|---|---|---|
| Leo's Loo Too | Tilting drum | 1–20 lb | Casa Leo rates it from 1 lb; keep automatic cleaning off and supervise small kittens anyway. |
| Neakasa M1 | Open-top | 2.2–33 lb | Under 2.2 lb: turn off automatic cleaning and use Kitten Mode (Neakasa). |
| ScoopFree SmartSpin | Tilting drum | 2.5–25 lb | Keep it unplugged or auto-clean off until a kitten is at least 2.5 lb and 6 months old (Amazon listing). |
| Litter-Robot 4 | Rotating globe | 3–25 lb | Under 3 lb: Whisker says leave it powered off and start cycles yourself ("semi-automatic" mode) until the kitten weighs 3 lb. |
| Litter-Robot 5 | Rotating globe | 3–30 lb | Under 3 lb: use semi-automatic mode (power off, cycle by hand) until the kitten reaches 3 lb (Whisker). |
| Litter-Robot EVO | Rotating globe | 3–19 lb | Under 3 lb: semi-automatic mode until the kitten reaches 3 lb (Whisker). |
| Purobot Ultra | Tilting drum | 3.3–22 lb | PETKIT recommends it for cats 6+ months old and at least 3.3 lb. |
| Purobot Max Pro 2 | Tilting drum | 3.3–22 lb | PETKIT: cats over 3.3 lb and older than 6 months. |
| PuraMax 2 | Tilting drum | 3.3–22 lb | PETKIT's FAQ gives 3.3 lb (1.5 kg) as the minimum for automatic mode. |
| Lesure Open-Top | Open-top | 3.3–18 lb | Not for kittens under 6 months (Amazon listing). |
| Furbulous Self-Packing | Enclosed scoop | 3.3–22 lb | Listing says cats over 3.3 lb; supervise small cats. |
| ScoopFree Crystal Smart | Rake + crystal tray | not published | PetSafe's ScoopFree guidance: keep it unplugged and scoop by hand until a kitten is 6 months old. |
| ELS PET Orbitie | Tilting drum | up to 21 lb | No minimum weight published that we could confirm; don't run it automatically for kittens. |
| ScoopFree Classic | Rake + crystal tray | up to 15 lb | Keep it unplugged and scoop by hand until a kitten is 6 months old (PetSafe). |
A worked example
Say you have a 4-month-old kitten that weighs 3.5 lb, and it will share the box with one adult cat. Enter 3.5 lb, 4 months and 2 cats. No box comes back as a clean fit. The Litter-Robots, the PuraMax 2, the Neakasa M1 and Leo's Loo Too clear their weight minimums but get a caution because the kitten is under 6 months; the Litter-Robot EVO gets a second flag for sitting within 1 lb of its 3 lb minimum on weight sensors alone. The Purobots, the SmartSpin, both ScoopFree Crystal boxes and the Lesure are marked not safe in automatic mode, because their makers set a 6-month minimum age, and so is the ELS PET Orbitie, because no minimum weight is published. The tool also reminds you that two cats call for three boxes. The practical answer: run any box with automatic cleaning off for a few more weeks, and keep a plain box out.
For the full background, read are self-cleaning litter boxes safe? and our kitten guide.
Frequently asked questions
What is the minimum weight for a self-cleaning litter box?
It depends on the model. Whisker's Litter-Robot 4, 5 and EVO need a cat of at least 3 lb for automatic mode, PETKIT's PuraMax 2 and Purobot models 3.3 lb, PetSafe's SmartSpin 2.5 lb and 6 months, and Neakasa's M1 2.2 lb. Below the minimum, the weight sensors may not notice the cat, so use the box with automatic cleaning off.
Can kittens use a self-cleaning litter box?
They can use the box, but most makers say not in automatic mode until the kitten passes a weight or age minimum. Whisker calls this semi-automatic mode: leave the robot off and start cycles yourself. Neakasa has a Kitten Mode, and PetSafe says to keep ScoopFree units unplugged until a kitten is six months old.
Are self-cleaning litter boxes dangerous for cats?
Well-designed boxes have several sensors and keep the entrance open during the cycle, so a cat can always step out. The documented death we know of involved a cheap box whose door closed on a cat's neck. WIRED won't recommend boxes that close completely while cleaning, and neither do we.
How many cats can share one automatic litter box?
Only a few makers publish a number: Whisker rates the Litter-Robot 4 for up to four cats, the Litter-Robot 5 for five and the EVO for two. Vets still recommend one litter box per cat plus one, so a single automatic box shouldn't be the only box in a multi-cat home.
Is this checker a substitute for the manual?
No. It applies each maker's published limits and named reviewers' findings to your answers. Always read the manual, supervise the first cycles and talk to your vet if your cat avoids the box or has health or mobility problems.