Rotating drum~$599Whisker
Whisker's entry model shrinks the globe to fit a 20.6-by-24.3-inch spot and drops the curtain lasers: its own FAQ says it relies on weight sensors to know a cat is inside. The trade shows up in the ratings, which stop at two cats and 19 lb, with a 14.5-inch interior height that Whisker itself says is tight for especially tall cats.
Approx. price
~$599
maker's store, not a live price
Best for: One or two average-size cats in an apartment
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. The maker does not state any anti-pinch protection.
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 7 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.
The EVO is the newest and smallest Litter-Robot, and owner discussion of it is thinner than for the LR4 or LR5. What does exist is dominated by one hardware complaint: a waste drawer that several owners cannot get to close flush, which some tie to smell escaping between cycles.
Beyond the drawer, reports are the familiar mix for a new product: one unit that would not finish onboarding, one that shed a part in its first fortnight, an app that kept showing the drawer as nearly full after it had been emptied. One owner went as far as calling it the worst purchase they had made after dealing with smeared waste daily. Others simply report their cats using it more than an older LR4 in the same home.
One or two cats up to its 19 lb rating, in a small space, is the brief it was designed for. Given the drawer reports, owners who have room for the LR4's larger footprint often recommend it instead, especially since the LR4 is frequently discounted to a similar price.
Several owners report the same thing. Some contacted Whisker and received a replacement drawer or base, though at least one found that did not solve it. Contact support within the return window if it will not sit flush.
Some owners think so and blame the drawer gap; one comparing directly with a relative's LR4 said the EVO needed much more cleaning to stay acceptable.
Whisker says kittens from 3 lb can use it automatically. One owner found it would not track a kitten of about 6.5 lb, so check the history in the app during the first weeks.
The EVO is smaller, 20.6 by 24.3 inches against the LR4's 22 by 27, but owners who can fit the LR4 often prefer it because of the EVO drawer reports and because the LR4 is regularly discounted to a similar price.
Rotating drum
Best for: Two or three average cats in a home that already uses clay clumping litter
Rotating drum
Best for: Large multi-cat homes that want visit-level tracking without a camera
Rotating drum
Best for: Multi-cat homes where telling similar-weight cats apart matters