PETKIT Purobot Ultra vs Litter-Robot 4: which should you buy?

Why the Litter-Robot 4 wins

• More cats. Whisker rates it for up to 4 cats. PETKIT gives no cat count for the Ultra, so we judge it for one.
• Bigger cats, bigger door. Cats up to 25 lb, against 22 lb. The door is 15.75 × 15.75 in; the Ultra’s is 9.84 × 8.54 in (PETKIT).
• Cheaper to buy, and a tester rated the Ultra lower. It costs $101 less. Cats.com scored the Ultra 3.8 of 5 and called it “not worth the hefty price tag” (Cats.com).

Buy the Purobot Ultra instead if you have one cat and want a camera and less emptying: it bags its own waste, goes up to 20 days between emptying instead of 8, and its refills cost less. $800 at Amazon, checked November 2, 2026.

Where they differ

Bold marks the better number. Every figure is the maker’s own, except the Litter-Robot 4’s noise, which a tester measured.

The same on both: clumping litter, a free app, and the box cleans itself a few minutes after your cat leaves. Neither needs a subscription to work.

Sources, read October 7, 2026: Whisker’s Litter-Robot 4 page and comparison chart (cameras), the Cats.com noise test, PETKIT’s Purobot Ultra page and warranty policy.

The Ultra is 1.06 in narrower and 5.41 in shorter, but 5.2 in deeper. PETKIT also asks for 1.97 in of space from walls (PETKIT). The Litter-Robot 4’s door is 15.75 in across; the Ultra’s is 9.84 in wide and 8.54 in tall.

Which one do the makers rate for your cats?

Whisker rates the Litter-Robot 4 for up to 4 cats. PETKIT gives no cat count for the Ultra. Its camera can tell up to 15 cats apart (PETKIT), but that is a camera feature, not a rating for how many cats the box can serve.

More cats fill either box faster than the one-cat figures. Whisker says two average cats usually means emptying the Litter-Robot 4 about twice a week (Whisker).

What each costs to own

The Ultra costs $101 more to buy, but its refills cost about $122–$239 less a year. Over 3 years, with one cat, the Ultra comes out about $265–$615 cheaper.

How we got these. Every part each maker says to replace, at the maker’s schedule and the price we could check. Litter-Robot 4: an OdorTrap pack and a carbon filter every 2–4 weeks (Whisker); OdorTrap at Whisker’s store price, $30 for 6 (Whisker, read November 2, 2026); filters at Whisker’s $30 for 6 (Whisker); one $12-for-10 liner each time you empty, about every 8 days (Whisker, price). Cheaper third-party bags exist. Purobot Ultra: one refill ring packs about 10 bags of up to 20 days each (PETKIT), at $49.99 for 4 on Amazon; PETKIT says only its own rings work (PETKIT). One N60 odor piece lasts 45–60 days (PETKIT), $19.99 for 3 (PETKIT).

Not counted: litter, more cats (both use more), and the optional apps. Whisker+ is $7.99 a month or $79.90 a year (Whisker). PETKIT’s product page does not list a price for Care+. Our other pages count only the OdorTrap packs for the Litter-Robot 4 and only the rings for the Ultra; on that basis the 3-year totals are $895–$1,090 and $868.

Who should buy which

Buy the Litter-Robot 4 if

• You have 2 to 4 cats. Whisker rates it for 4; PETKIT gives no count for the Ultra.
• A cat weighs over 22 lb. Whisker rates the 4 to 25 lb and says it works for large breeds like Maine Coons (Whisker).
• Your cat is big, old or wary of small doors. The 4’s door is 15.75 × 15.75 in; the Ultra’s is 9.84 × 8.54 in.
• You want to spend less up front. It is $101 less at Amazon.
• The box must sit on carpet. PETKIT says the Ultra must not (PETKIT). Whisker sells a Carpet Tray for the 4 on carpet 3 mm or thicker (Whisker).

Buy the Purobot Ultra if

• You have one cat of 3.3–22 lb.
• You want to empty it less and never touch a bag. It seals the bag and fits a new one itself, and goes up to 20 days with one cat (PETKIT). PETKIT says to empty it sooner in hot, humid weather (PETKIT).
• You want a camera on the box: 1080p video and photos of each visit (PETKIT). Saved video beyond the same day needs PETKIT Care+ (PETKIT, Cats.com).
• You want lower running costs and a 2-year warranty. The 4 has 1 year; Whisker sells 3 years for $129 (Whisker). PETKIT’s 2 years covers US units bought on or after January 1, 2025 (PETKIT).
• Your WiFi is 5 GHz only. The 4 needs 2.4 GHz (Whisker).

What testers found

We do not test litter boxes. These are named testers’ findings.

• Purobot Ultra: Cats.com bought one and used it for over six weeks (Cats.com). It scored 3.8 of 5 overall (Cats.com) and 4.5 of 5 for odor (Cats.com). The face matching mixed up two cats that “look nothing alike” (Cats.com). Once the bag refill stopped because it took a full bag nearby for a cat (Cats.com). Its verdict: “not worth the hefty price tag” (Cats.com).
• Litter-Robot 4: Cats.com tested it for months (Cats.com). Its testers noticed no odor unless the drawer was open (Cats.com), but called the 14 in litter bed small (Cats.com). TechnoMeow’s tester saw sensors misfire after a few months (TechnoMeow). Engadget saw uneven sifting and sensor glitches (Engadget).

Safety and recalls

Both stop when a cat is inside. Whisker: lasers, weight sensors and anti-obstruction checks. PETKIT: 20 sensors; the drum stops when a cat comes near. Our screen of the CPSC recall database (November 2, 2026) found no recall naming either box. How we screen.

Questions buyers ask

Sources

PETKIT’s and Whisker’s pages and the reviews read between October 1 and October 7, 2026. Amazon prices and listings checked November 2, 2026. These are the makers’ figures and named testers’ findings, not our tests. How we work.

What we checked and what we did not

• Checked: every maker figure on this page against the maker’s own page on October 7, 2026, and both Amazon listings by model (prices from Amazon’s product data, checked November 2, 2026).
• Not checked: we did not test either box. PETKIT’s noise figure is its own claim. PETKIT does not publish a cat count or a Care+ price. Amazon prices change; check the current price before you buy.

Next: Litter-Robot 4 · Purobot Ultra · best automatic litter box, every brand · multiple cats · which Litter-Robot · which PETKIT