Last updated: November 1, 2026
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The Litter-Robot 4 costs about twice as much as the PETKIT Purobot Max 3 and the PETKIT PuraMax 2 costs less still, so the choice is mostly about price and cat size. The Litter-Robot 4 takes cats up to 25 pounds and serves up to four. PETKIT lists the Max 3 for cats from 3.3 to 22 pounds.
Check the Litter-Robot 4 price on Amazon
Comparison table
| Feature | Litter-Robot 4 | PETKIT Purobot Max 3 | PETKIT PuraMax 2 |
|---|---|---|---|
| Amazon price | $699.00 | $369.99 | $299.99 |
| Mechanism | Rotating globe with sifting | Rotating drum, 76 L | Rotating drum, 76 L |
| Cat weight | 3 to 25 pounds | 3.3 to 22 pounds, 6 months and older | From 3.3 pounds, maximum conflicts between 17.6 and 22 pounds |
| Cats suited | Up to 4 | Not stated | Not stated; one box per cat plus one is advised |
| Waste drawer | Volume not stated; empty about every 7 to 10 days | 7 L side bin; up to 15 days for one cat | 7 L sealed bin; up to 15 days for one cat |
| Litter | Clumping clay; some silica; no tofu or non-clumping | Clumping clay, tofu, mixed; no crystal or non-clumping | Most clumping litters; no crystal or non-clumping |
| App | Optional; runs from a control panel without it | Optional; top panel covers the basics | Optional for the clean cycle; scheduling and logs need it |
| Battery backup | Sold separately, 24 to 48 hours of reserve power | Not stated | Not stated |
| Paid service | Whisker+ is optional | None for the device | None mentioned |
| Odor filter | Carbon filter every 2 to 4 weeks | N50 cartridge about every 30 days, $19.99 for 3 | N50 cartridge about every 30 days, $19.99 for 3 |
| Warranty | 1 year, 3 years with a $129 extension per Whisker | 2 years on US purchases through PETKIT or authorized distributors | 2 years per PETKIT’s warranty page; the manual says 1 year |
Prices are the Amazon listing prices on November 1, 2026, and they change often. Specifications come from Whisker and PETKIT pages and manuals, with figures left out where sources disagree.
Choose the Litter-Robot 4 for large cats or several cats
Whisker lists a 3 to 25 pound cat range and a limit of four cats. Laser and weight sensors watch the globe, and the app shows a 7-day visit and weight history per cat. Whisker+ adds longer history and trends for a fee, and Whisker states the app is not required for the machine to run. A backup battery kit is sold separately. The standard warranty is 1 year and covers accidental damage, power surges and mechanical failure, and an extended 3-year plan costs $129 if bought in the first year.
The recurring complaints in published reviews are the $699 price and a globe interior that is tight for large cats. Reviewers also note ongoing carbon filter costs. Whisker lists a 90-day in-home trial, and the buyer pays return shipping.
Choose the PETKIT Purobot Max 3 for a lower price with tofu litter
The Purobot Max 3 uses a 76 liter drum and a 7 liter side-mounted waste bin. PETKIT lists 12 anti-pinch sensors and an odor system with a replaceable N50 cartridge. It supports tofu and mixed litters, which the Litter-Robot does not. The PETKIT lists a 2-year warranty for US purchases through its own store or authorized distributors, and says third-party sellers such as Amazon follow their own return policy, so check the warranty terms on the Amazon listing.
One published review of this model was found. It notes that deep cleaning is fiddly, that the box has no camera, and that the running cost of cartridges and liners adds up.
PETKIT Purobot Max 3 on Amazon
Choose the PETKIT PuraMax 2 for the lowest price
The PuraMax 2 has the same 76 liter drum and 7 liter sealed bin and costs $299.99 on Amazon. It runs its clean cycle without the app, while scheduling, logs and alerts need it. PETKIT’s documents give maximum cat weights of 17.6, 18 and 22 pounds, so a cat near that range needs a check with PETKIT support first.
Two or more reviews report that it is bulky, hard to deep clean, does not take crystal litter, and is unsuited to kittens under about 6 months.
What none of these do
None of the three works with crystal or non-clumping litter in every version, and none replaces a vet visit, because the weight readings are not a medical measure. A cat that avoids a rotating globe or drum may refuse all three. Whisker and PETKIT both ask that the machine be set on a hard, level floor.
A box with a camera is a different product. PETKIT sells the Purobot Max Pro 2 with an AI camera at $494.99 on Amazon, and this page did not compare it. A Tom’s Guide review of that model found the interior cramped for two 15 pound cats. Feeders with a camera are in the feeder guide.
How this page was put together
Each specification comes from manufacturer pages and manuals or from published reviews, as the Editorial Policy describes. Where sources disagree, the page names the conflict. Commission rates do not set the order of the picks.