Litter-Robot 4 vs PETKIT Purobot Max Pro 2: Which Self-Cleaning Box Fits Your Cats?

Short answer: For most homes, the Whisker Litter-Robot 4 is the safer pick: it takes heavier cats (up to 25 pounds), has a much larger entry, and its globe design doesn't depend on a camera or a subscription. Pick the PETKIT Purobot Max Pro 2 instead if you want camera-based visit records, per-cat face recognition and 5 GHz Wi-Fi at a lower list price, and every cat in the house weighs under 22 pounds.

These two sit near the top of their makers' lineups and are often cross-shopped. Both rotate to sift clumps out of clean litter and both log visits in an app. They differ in who they fit, what they record, and what you keep buying.

Which PETKIT model we compared

On October 13, 2026, PETKIT's US store listed four Purobot models: the Max Pro 2, Max 3, Ultra and Crystal Duo. The original Purobot Max Pro has been replaced by the Max Pro 2, which PETKIT says has a 43% larger entry. We chose the Max Pro 2 because, like the Litter-Robot 4, it is an enclosed rotating box with a sealed waste compartment. The Ultra adds automatic bagging at a higher price tier, and the Max 3 is a camera-free model in a lower one. We mention both where they change the answer.

Side-by-side decision table

What to look for

Five factors decide this matchup more than any feature list:

1. Your heaviest cat's weight. The Litter-Robot 4 goes to 25 pounds, the Max Pro 2 to 22.
2. The litter you want to use. Whisker wants clumping clay; PETKIT also takes tofu and mixed litter.
3. How much you want recorded. Weight logs are free on both; video and stool flags need the PETKIT camera.
4. Your Wi-Fi. The Litter-Robot 4 needs a 2.4 GHz network; the Max Pro 2 also joins 5 GHz.
5. What you'll keep buying. Filters or deodorizers, bags and an optional plan on both.

How they clean

The Litter-Robot 4 turns its whole globe after a cat leaves, letting clean litter pass through a screen while clumps drop into a drawer below. The cycle starts a few minutes after the cat exits, you can stretch the delay to 30 minutes for a skittish cat, and Whisker's QuietSift design is meant to keep the motor quiet.

The Max Pro 2 turns a drum. Clumps go into an 8-liter side bin, where a drawstring bag lets you tie off and lift out the waste without touching it. It ships with two sifters, one for larger tofu or mixed particles and one for fine clay. PETKIT advises against litter pieces longer than about half an inch.

Fit: cat size, entry and space

This is the biggest practical difference. The Litter-Robot 4 accepts cats up to 25 pounds through a 15.75-inch square opening with 16.5 inches of interior headroom. The Max Pro 2 stops at 22 pounds, and its entry is about 10.5 inches across. Tom's Guide (December 2025) liked the Max Pro 2 overall but wished the interior were roomier so its cats could turn around more easily.

On the other hand, the Max Pro 2 is about six inches shorter than the Litter-Robot 4. If a low shelf or windowsill sits above the spot you have in mind, measure both.

Litter and waste

Whisker recommends clumping clay. It warns against plant-based, wood pellet, newspaper and non-clumping litters, and says white or translucent litter can throw off its litter-level and drawer-full readings. That rules out many tofu and pine litters people like.

PETKIT accepts clumping clay, tofu and mixed litters. If you want the urine pH feature, Tom's Guide notes it relies on PETKIT's own tofu-mixed litter.

On emptying, PETKIT quotes up to 17 days for one cat; Whisker quotes about 8 days for the Litter-Robot 4. Sources don't line up neatly here: Tom's Guide described the Max Pro 2's 8-liter bin as small next to rival boxes. Whisker doesn't publish the drawer's volume, so treat both figures as single-cat estimates and expect to empty more often with each extra cat.

Safety sensors and placement

Whisker uses laser and weight sensors to detect a cat entering and leaving, and the globe won't cycle while a cat is inside. Kittens must weigh at least 3 pounds for automatic mode; below that, Whisker recommends a supervised semi-automatic routine. Whisker's Amazon listing also says not to push the unit against a wall or into a corner.

PETKIT lists 12 sensors on the Max Pro 2, including proximity and weight sensing, and an anti-pinch design that keeps the entry open while the drum turns. PETKIT doesn't recommend it for kittens or cats under 3.3 pounds; in mixed-age homes, its Kitten Protection Mode turns off automatic and scheduled cleaning. It must sit on a hard, level floor, since carpet can interfere with the sensors.

App, camera and subscriptions

Litter-Robot 4. The free Whisker app shows real-time litter and drawer levels, a 7-day view of visits and weights, and remote controls. Cats are identified by weight, which The Irish Times review (October 2026) found harder when two cats are a similar size. Whisker+ is optional, sold monthly or yearly with a 30-day free trial, and adds up to two years of history, trend reports and daily recaps. Whisker says features that were free stay free without it.

Purobot Max Pro 2. The camera records each visit, identifies cats by face plus weight, and flags stool changes and yowling. Tom's Guide found these health features in the free plan. PETKIT Care+ is optional and extends video history (PETKIT cites 30 days; Tom's Guide describes a lower Basic tier with 7 days of highlights). You can set camera hours or turn the camera off in the app, and the box keeps cleaning on its preset schedule if Wi-Fi drops.

Neither box's health data is a diagnosis. It's a record you can bring to your veterinarian.

Noise

Whisker doesn't publish a decibel figure for the Litter-Robot 4, but independent reviewers, including Reviewed and The Irish Times, describe it as very quiet in use. PETKIT claims 35 dB for the Max Pro 2 on its own site, while its Amazon listing says 35–45 dB. We couldn't find an independent measurement for either.

Warranty and support

Whisker includes one year of WhiskerCare. A three-year plan costs extra (it's included in most Whisker bundles) and covers accidental damage, power surges and breakdowns, with free shipping both ways and no deductibles. Reviewed listed the short standard warranty as a con.

PETKIT gives the Max Pro 2 a two-year limited warranty in the US for purchases from PETKIT or authorized distributors. PETKIT chooses whether to replace parts, replace the unit or refund, return shipping may fall on the customer depending on the case, and wear on consumable parts isn't covered. Purchases from third-party sellers follow that seller's return policy.

Real ongoing cost

At list price on each maker's site when we checked, the Litter-Robot 4 sat in a higher price tier than the Max Pro 2. Over a few years, consumables and an optional plan can narrow or widen that gap, so price out a year of filters, bags and litter for your number of cats. Check Whisker+ and the PETKIT app for current plan terms.

Pick the Litter-Robot 4 if…

• Any cat is over 22 pounds, or you have a large breed that is still growing.
• Your cat is wary of small openings or enclosed spaces.
• You already use clumping clay litter and don't want a camera in the litter box.
• You want the option of an extended warranty that covers accidental damage.
• You'd like to add automatic litter refills later with the LitterHopper.

Litter-Robot 4 at Whisker

Pick the PETKIT Purobot Max Pro 2 if…

• You have several similar-size cats and want each visit tied to the right cat.
• You want video and stool records to share with your veterinarian.
• You prefer tofu or mixed litter.
• Your home network is 5 GHz or you want a longer standard warranty.
• Every cat is between 3.3 and 22 pounds.

Max Pro 2 at PETKIT

Consider something else if…

• Your cats are very large or you have five: Whisker's Litter-Robot 5 is rated for up to five cats from 3 to 30 pounds.
• You like PETKIT but don't want a camera: the Purobot Max 3 has the same 3.3–22 pound range, weight-only cat ID, 2.4 GHz Wi-Fi and a 7 L bin, in a lower price tier.
• You want no bag handling at all: the Purobot Ultra seals and replaces its own bags, but needs PETKIT's proprietary refill rings.

How we chose

This comparison is based on Whisker's and PETKIT's product pages, FAQs, warranty policies and subscription terms, PETKIT's 2026 lineup guide, independent reviews from Tom's Guide, The Irish Times and Reviewed, and ASPCA guidance. PawCog has not used, examined or evaluated either litter box in person. Where sources disagree, we note it and give the manufacturer's figure.

FAQ

Is the Litter-Robot 4 still sold now that the Litter-Robot 5 is out?

Yes. As of October 13, 2026, Whisker still lists the Litter-Robot 4 alongside the Litter-Robot 5, 5 Pro and EVO, and it remains on Amazon.

Can a Maine Coon use the PETKIT Purobot Max Pro 2?

Only if it weighs 22 pounds or less, PETKIT's upper limit. The entry is about 10.5 inches wide. For bigger cats, the Litter-Robot 4 (25 pounds) or Litter-Robot 5 (30 pounds) leave more margin.

Does the Max Pro 2 camera need a subscription?

No. Tom's Guide found that stool monitoring, yowling detection and urine pH tracking are included in PETKIT's free plan, along with some cloud video storage. PETKIT Care+ is optional and mainly extends how long video history is kept.

Can I use regular trash bags in either box?

The Irish Times reports that generic bags fit the Litter-Robot 4's drawer. PETKIT says standard bags can work in the Max Pro 2, but some are too thick or the wrong size for its drawstring system, so it recommends its own bags.

Will one self-cleaning box be enough for my cats?

Whisker rates the Litter-Robot 4 for up to four cats. The ASPCA's general guideline is one litter box per cat plus one extra, so if your cats are particular or one starts going outside the box, add a second box and talk to your veterinarian.

Sources

• Litter-Robot 4 product page, Whisker (checked 2026-10-13)
• Litter-Robot 4 vs. EVO comparison, Whisker (checked 2026-10-13)
• Whisker+ membership terms, Whisker (checked 2026-10-13)
• Purobot Max Pro 2 product page and FAQ, PETKIT (checked 2026-10-13)
• 2026 PETKIT automatic litter box buying guide, PETKIT (checked 2026-10-13)
• Limited Warranty Policy, PETKIT (checked 2026-10-13)
• Petkit Purobot Max Pro 2 review, Tom's Guide (checked 2026-10-13)
• Litter Robot 4 review, The Irish Times (checked 2026-10-13)
• Litter-Robot 4 review, Reviewed (checked 2026-10-13)
• Litter Box Problems, ASPCA (checked 2026-10-13)