The short answer
Self-cleaning boxes use weight sensors to know a cat is inside, so makers set a minimum cat weight for automatic mode: about 3 lb for the Litter-Robot 4 and 3.3 lb for PETKIT's PuraMax 2 and Neakasa's M1 Plus. Below that, use the box with cleaning switched to manual or a kitten mode.
Stated minimums
| Box | Maker statement |
|---|---|
| Litter-Robot 4 | Each cat at least 3 lb (1.4 kg) |
| PETKIT PuraMax 2 | 3.3–22 lb; not for pets under 6 months |
| Neakasa M1 Plus | 3.3–33 lb; Kitten Mode below 3.3 lb |
| WARCAT 90L | 2.2–24.2 lb |
| Smarty Pear Leo's Loo Too | 1–20 lb |
Kitten modes
Some boxes add a mode that stops automatic rotation entirely: Neakasa M1 Plus and Furrykiddy both offer one. Clean manually from the app until your kitten is heavy enough.
SafetyNever leave a kitten under the minimum weight with automatic cycling on.
Senior and small cats
The same weight limits apply to small adult cats. Low entries help seniors: the Meowant SC09 Plus has an 8.27 in entrance and PetSafe's SmartSpin sits 12 in off the ground.
Products mentioned
Questions readers ask
Can a kitten use a Litter-Robot?
Whisker states each cat must weigh at least 3 lb for automatic mode; use manual cleaning before then.
Which box takes the lightest cats?
Smarty Pear states 1–20 lb for Leo's Loo Too.