Rotating drum~$699Whisker
Four years on, this is still the reference point everything else in the category gets measured against. Three curtain lasers across the bezel and a scale in the base decide when a cat has left, and anti-pinch sensors on both sides of the drawer chute stop and reverse the globe if something is in the way. Whisker rates it for cats from 3 to 25 lb and up to four of them, and it runs on ordinary clay clumping litter.
Approx. price
~$699
maker's store, not a live price
Best for: Two or three average cats in a home that already uses clay clumping litter
Whisker says the sensor detects cats from 3 lb. At the usual rate of about a pound a month, that means leaving automatic cleaning off until roughly 3 months. Below the threshold, a kitten may not register at all, and the box could start a cycle with it inside.
Detection: weight, infrared / radar. The maker states anti-pinch protection on the moving part, by sensor or by design.
How minimum weights work, and what to do below themThe maker publishes no drawer volume, so the days cannot be worked out. Its own claim is up to 8 days for one cat.
The two lists above are drawn from the maker’s own pages, manuals and prices, not from owner reports. Where owner discussion has been read it appears in its own section below, so the two are never mistaken for each other.
For most owners the Litter-Robot 4 does what it promises: the scooping stops, the drawer gets emptied roughly weekly, and the house stops smelling of litter. The complaints that do come up tend to trace back to setup, such as too little litter, a short cycle delay or a litter that smears, and to the minority of cats whose aim misses the litter bed.
The mechanism is simple, and owners who run several units for years say it holds up. When it does go wrong the patterns are recognisable: cycles repeatedly interrupted, a drawer-full sensor that misreads, and smell creeping back when urine gets under or onto the liner. A small number of owners in 2023 reported the box cycling with a cat inside. Whisker asked each of them for details, and the LR4's pinch sensors on the waste chute are a separate protection that owners have tested with objects.
It suits most average cats and households of up to about four, especially where someone is happy to keep the litter at the fill line and deep clean every few months. Owners of side-peeing or very tall cats, and people who want zero maintenance, are the ones who end up disappointed; the LR5's taller globe and PETKIT's cheaper drums are the usual alternatives people weigh it against.
Owners typically empty the drawer about once a week, top up litter (or let a LitterHopper do it) and deep clean every few months. Some never deep clean; others with messy cats wipe it down weekly. It removes scooping, not all maintenance.
Owners trace it to cycles being interrupted so the drawer stays exposed, litter below the fill line, a soft-clumping litter, or urine hitting the liner. Fixing those usually helps, and Whisker has replaced units where the smell persisted.
It is designed not to, using curtain lasers and a weight scale. A few owners reported it happening in 2023 and Whisker asked each for their serial number. The chute also has pinch sensors that stop and reverse the globe if something is in the way.
Usually a litter that clumps softly or a cycle delay too short for the clump to set. Owners lengthen the delay to 15 minutes or more, keep litter at the fill line and use a hard-clumping clay.
No. The robot works fully without it. The membership mainly adds longer history and recorded video features, which owners of the LR4 argued about when it launched in 2025.
Owners fill the litter to the line, add Whisker's fence or a DIY splash guard, and some switch to a taller globe such as the LR5. Cats that stand to pee are the case the LR4 handles worst.
Rotating drum
Best for: Large multi-cat homes that want visit-level tracking without a camera
Rotating drum
Best for: One or two average-size cats in an apartment
Rotating drum
Best for: Multi-cat homes where telling similar-weight cats apart matters