Litter-Robot 4 vs. PETKIT Purobot
The two automatic litter boxes people compare most, judged for a two-cat house from the limits their makers publish. Only one of the two brands publishes enough to be judged, and that is most of the answer.
For a two-cat house, the Whisker Litter-Robot 4. Whisker publishes the figures a buyer needs to check: 4 cats, a 3 lb to 25 lb weight range, 8 days of waste capacity for one cat, clumping litter, no subscription required. Against this house's 2 cats at 8 to 14 lb it clears every limit, at $699 list ($699 on Amazon when checked).
The PETKIT Purobot Max Pro 2 costs less at $400 on Amazon, and PETKIT does not publish a cat weight range or a cat count for it, so this page cannot judge it against the house. The PETKIT Purobot Ultra does publish: 3.3 lb to 22 lb and 20 days of capacity, at $900 list. If you want PETKIT, that is the one whose limits you can check.
The Amazon links on this page are affiliate links: if you buy through one we may earn a commission, at no extra cost to you. It does not change which units are picked. How that works.
| Model | Cats, up to | Cat weight, from | Cat weight, to | Drawer lasts, one cat | Entry height | Litter | Warranty | Fit | Price | |
|---|---|---|---|---|---|---|---|---|---|---|
| Our pick | Whisker Litter-Robot 4 | 4 | 3 lb | 25 lb | 8 days | 15.8 in | clumping | 1 year | Clears the published limits | $699 at Amazon |
| Not judged here | PETKIT Purobot Max Pro 2 | not captured | not captured | not captured | not captured | not captured | not captured | 2 years | Maker does not publish the limit | $400 at Amazon |
Who this is for
Read on if it is down to a Litter-Robot 4 or a PETKIT Purobot and you want what each maker actually publishes about cat weight, capacity and litter, judged for two cats. The three-way page adds the Neakasa M1 Plus.
Against the same house
The house is two cats, the heaviest 14 lb and the lightest 8 lb, on clumping litter. Whisker answers all of that in writing for the Litter-Robot 4: cats from 3 lb to 25 lb, up to 4 of them, on clumping litter. Both cats sit inside every one of those limits. PETKIT publishes a weight range for the Purobot Ultra and none for the PETKIT Purobot Max Pro 2, and a cat count for neither, so the PETKIT side reads unknown rather than fails.
Adjust to your house. Change the numbers and this box re-judges the models compared here against your house, with the same rules and the same maker figures. The picks and tables above stay on the page’s own house.
Our pickWhisker Litter-Robot 4
The reference: every limit published, every one cleared
$699 at Amazon, September 20, 20264 cats, up to3 lb cat weight, from25 lb cat weight, to8 days drawer lasts, one cat
Whisker rates the Litter-Robot 4 for cats from 3 lb to 25 lb and for up to 4 cats, on clumping litter, with a drawer rated at 8 days for a single cat and no subscription before it will cycle. It is the only unit on this page whose maker fills in every column, down to where it goes: 22 in by 27 in, 29.5 in tall, an entry 15.8 in off the floor. It lists at $699 and was $699 on Amazon when checked.
Price as of September 20, 2026; the listing we verified as the bare unit. Sold by Spreetail when we checked; we could not confirm whether that seller is an authorized dealer for the maker's warranty, so check before you buy.
Living with it
Whisker's instructions set the rhythm: the first fill goes to just under the raised fill line, the globe needs a full wash only every month or few, and carbon filters and odor-trap packs get changed every few weeks. Owners report this machine tends to fail early if it fails at all; some say it stopped rotating or cycling inside the first two months, and Whisker's fix was a replacement power adapter rather than a new unit.
- Consumables
- Replace carbon filter/OdorTrap every 2-4 weeks whisker.com
- What consumables cost
- Consumables Kickstart Kit: $80 (reg. $115) whisker.com
- Subscription
- Whisker+ add-on renews at $7.99/month whisker.com
- Set-up
- Fill litter just below the raised fill line, about 8-10 lb or roughly a gallon litter-robot.com
- Maintenance
- Wash the globe roughly every 1-3 months litter-robot.com
- Warranty
- 90-day in-home trial on top of the warranty whisker.com
- Known issue
- White/translucent litter confuses the level sensor whisker.com
What long-term reviewers and owners report, each line cited to its published source; not our own testing.
- Independent testing measured the Litter-Robot 4's cycle noise at about 37 decibels, roughly whisper-quiet. cats.com
- A recurring owner complaint is early reliability failures, with units that stop rotating or cycling within one to two months of purchase. cats.com
- Owners flag the waste drawer liners as a recurring cost and a durability weak point: one reports needing a second replacement because of tears. cats.com
- Despite the complaints, owners who stick with the Litter-Robot 4 say they wouldn't return to a manual litter tray. catster.com
What independent testers found
We do not test units ourselves. These are figures and verdicts published by named testers, with the maker’s claim beside them where the tester gave it; where a tester relays owners’ reports rather than a measurement, the row says so.
| What | Finding | Tester |
|---|---|---|
| Cycle time | 3-30 minutes, adjustable cycle timer | Cats.com |
| Noise | About 37 dB measured during cycling | Cats.com |
| Noted | Testers noticed no litter box odor unless the waste drawer itself was open | Cats.com |
- Catster gave the Litter-Robot 4 a 4.6 out of 5 rating. (4.6/5 rating) Catster
- Cats.com rates the Litter-Robot 4 as likely the best self-cleaning, automatic litter box on the market. Cats.com
What you give up
Price, and the shorter base warranty: 1 year against 2 years from PETKIT. The drum asks a cat to walk into an enclosed chamber and step over a rim 15.8 in up, higher than the PETKIT Purobot Ultra's 10.4 in.
Figures from whisker.com; recall screen: no published CPSC recall names this exact model (screened 2026-09-17) (how we screen, CPSC).
Not judged herePETKIT Purobot Max Pro 2
The PETKIT: cheaper, and unjudged because PETKIT publishes no limits for it
$400 at Amazon, September 20, 2026
The PETKIT Purobot Max Pro 2 was $400 on Amazon against a $550 list when checked, with a 2 years warranty. PETKIT's page for it states no cat weight range and no cat count, so this page cannot judge it against two cats at 8 to 14 lb; it reads unknown, which is a blank, not a failure. The PETKIT Purobot Ultra is the PETKIT that does publish: 3.3 lb to 22 lb, 20 days of capacity, clumping litter, at $900 list.
Price as of September 20, 2026; the listing we verified as the bare unit. Sold by PETKIT-US, the maker's own storefront, when we checked.
Living with it
PETKIT's manual is where the running costs hide. The waste bin takes PETKIT's own bags rather than a generic liner, a standing cost the list price does not include. The camera is the part with a subscription attached: full video playback needs PETKIT's Care+ tier, and outside the camera's scheduled hours it records nothing.
- Consumables
- Must use PETKIT's specialized trash bag petkit.com (manual)
- What consumables cost
- PETKIT sells fitted trash bags for this box (recurring purchase) petkit.com
- Subscription
- Care+ subscription needed for full video; non-refundable petkit.com (manual)
- Set-up
- Maintenance Mode rotates the cylinder opening upward to refill litter petkit.com (manual)
- Maintenance
- Manual: regularly clean or replace specific listed parts petkit.com (manual)
- Warranty
- Dishwasher cleaning voids the warranty petkit.com
- Known issue
- Litter granules capped at 12mm long, 3mm diameter petkit.com (manual)
- Camera and data
- Camera off-schedule = no recording, only a 5-min live view petkit.com (manual)
What you give up
Any way to check it against your cats from PETKIT's own figures. If that matters, buy the Ultra, whose limits are published, or the Litter-Robot.
Figures from petkit.com; recall screen: no published CPSC recall names this exact model (screened 2026-09-17) (how we screen, CPSC).
The 3 Litter-Robot 4 and PETKIT Purobot models compared here, against that house
| Model | Verdict | What decided it |
|---|---|---|
| Whisker Litter-Robot 4 | Clears the published limits | cat weight limit is 25 lb; you need 14 lb whisker.com; minimum cat weight is 3 lb whisker.com; rated for up to 4 cats whisker.com; works with clumping litter whisker.com |
| PETKIT Purobot Max Pro 2 | Maker does not publish the limit | the maker does not publish a cat weight range; the maker does not say how many cats it is rated for; the maker does not say which litter it takes |
| PETKIT Purobot Ultra | Maker does not publish the limit | the maker does not say how many cats it is rated for |
Side by side, from the makers’ own documents
“Not captured” means the maker’s page we captured does not state it: a gap in our record, not a zero, and never filled from a sibling model. “No verified listing” means no Amazon listing for the bare unit passed our identity check yet. A price marked “list” is the maker’s list price, shown where no listing passed; a bare price is what the verified Amazon listing showed when we checked.
| Model | Cats, up to | Cat weight, from | Cat weight, to | Drawer lasts, one cat | Waste drawer | Litter | Subscription required | Warranty | Price |
|---|---|---|---|---|---|---|---|---|---|
| Whisker Litter-Robot 4 | 4 | 3 lb | 25 lb | 8 days | not captured | clumping | no | 1 year | $699 |
| PETKIT Purobot Max Pro 2 | not captured | not captured | not captured | not captured | not captured | not captured | not captured | 2 years | $400 list $550 |
 PETKIT Purobot Ultra | not captured | 3.3 lb | 22 lb | 20 days | not captured | clumping | no | 2 years | $800 list $900 |
Buying it right
A search for any of these models returns bundles, last year’s model under a similar name and, often, the same unit under two listings at different prices. We link only a listing whose own title and model number match the bare unit. Check the seller is the maker or Amazon itself, and that the model number on the box matches the one on this page.
Whisker Litter-Robot 4
- The listing we verified: “Whisker Litter-Robot 4, White - Automatic”, $699 when checked. Brand and full model name in the listing's own title; no bundle, variant or accessory marker. Its own model number reads LR4-0101-00-US; the maker's is LR4-0301-00-US.
- “Whisker Litter-Robot 4 Supply Bundle, Black”, $749: a bundle or a kit, not the bare unit this page judges. Its own model number reads LR4-0301-00-CA.
- “Whisker Litter-Robot 4 Supply & Accessory Bundle, Black - Automatic”, $799: An accessory or part listing ('accessory'), not the unit. Its own model number reads LR4-0301-00-CA.
- “Whisker Litter-Robot 4 with Step & Fence, Black - Automatic”, $699: a bundle or a kit, not the bare unit this page judges; it was the same price as the listing we link when checked. Its own model number reads LR4-0301-00-CA.
PETKIT Purobot Max Pro 2
- The listing we verified: “PETKIT Purobot Max Pro2 Automatic Cat Litter Box with 210° AI-Camera (PUROBOT MAX 3)”, $400 when checked. Brand and full model name in the listing's own title; no bundle, variant or accessory marker.
- “PETKIT Purobot Max Pro 2 AI-Camera Self Cleaning Cat Litter Box Odor-Free”, $550: Listing is the '2 AI' variant, a different product from the 'Purobot Max Pro 2' in our record.
- “PETKIT Purobot Max 3 Automatic Litter Box Large Opening Odor Control Safety”, $400: a different model that a search for this one returns.
- “PETKIT New Cat Litter Pad Max for PURAMAX 2 and Purobot Max Pro Automatic Self-Cleaning Cat Litter Box, High Performance Leakproof Litter Mat, Waterproof, Anti-Stick, Scratch-Resistant Cylinder Pad”, $40: An accessory or part listing ('litter mat'), not the unit.
- “PETKIT N50 Odor Eliminator 2.0 Exclusive for PuraMax and PuraMax 2 Self-Cleaning Cat Litter Box, Automatic Cat Toilet Box Smell Control Remover (Pack of 3)”, $20: An accessory or part listing ('pack of'), not the unit.
What this page can’t promise
Side by side means side by side on what the makers publish. An empty cell is neither a failing grade nor a pass: the PETKIT Purobot Max Pro 2 may suit more cats than this house has, but PETKIT does not say so anywhere we can quote.
Nothing here was tested by us: the measured figures and review scores belong to the testers named beside them, and the complaints are owners' reports. Prices move; both units were selling under list when checked.
A drawer figure is a maker's number for one cat of its own chosen size on its own chosen litter, and the page cannot know your cats, your litter or how much of the day they are home.
Questions people ask
Is the Litter-Robot 4 or the PETKIT better for two cats?
The Whisker Litter-Robot 4, because Whisker publishes a 4-cat rating and a 3 lb to 25 lb weight range that this house sits inside. PETKIT publishes neither for the Purobot Max Pro 2, so it cannot be judged.
Does either one need a subscription?
The Whisker Litter-Robot 4 does not; Whisker states that it cycles with no subscription. On the PETKIT Purobot Max Pro 2 the box itself does not, but PETKIT's manual puts full video playback from its camera behind the paid Care+ tier, and the waste bin takes PETKIT's own bags rather than a generic liner.
Which holds more waste?
Of the units with a published figure, the PETKIT Purobot Ultra at 20 days for one cat against the Whisker Litter-Robot 4's 8 days. Both figures are the makers' single-cat claims.
Other houses we judged
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- Small yardThe best robot lawn mower for a small yard
A small suburban lawn, a gentle grade, and a couple of beds to steer around. Almost every robot mower we track clears a yard this size, so the question stops being which one is big enough and starts being which one is worth what it costs.
- Inground poolThe best robotic pool cleaner for an inground pool
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An above-ground pool 24 feet across, on a soft liner, with a wall you can reach over. The maker's own pool-type rating decides this page before anything else gets a say: it rules out 5 of the 13 cleaners judged here on its own.
- Three catsThe best automatic litter box for multiple cats
3 cats, one of them big and one of them small, and one box that has to serve all of them. Two published limits decide it: the number of cats the maker rates the box for, and the weight range its sensors were built around.
- ComparedLitter-Robot 4 vs. PETKIT vs. Neakasa
Litter-Robot 4, PETKIT Purobot Max Pro 2 and Neakasa M1 Plus against one two-cat house, on the limits their makers publish. Only one can be judged.
- Pet hair, hard floorsThe best robot vacuum for pet hair on hard floors
A shedding dog or two cats, hard floors through most of the house, low thresholds between the rooms, and a wish that the bin emptied itself. Two robot vacuums come out of that house as picks, judged from the limits their makers publish rather than from a lab's dust-pickup score.
- GuideMeasure before you buy
Every home robot is sold against a limit, and every maker calls that limit something different on its spec page. Here is how to get your own numbers first.
- GuideApps, subscriptions and what stops working offline
Every one of these machines still moves without the internet. What you lose is the map, the schedule, the history and, on some of them, the reason you paid extra.
- GuideRecalls and battery safety for home robots
Five recalls cover every robotic pool cleaner, mower, vacuum and litter box sold in the United States since 2020, and every one of them was about heat.
Whisker Litter-Robot 4Our pick
$699 at Amazon