# Litter-Robot 4 vs PETKIT PuraMax 2: Which to Buy > Litter-Robot 4 vs PETKIT PuraMax 2: weight limits, entry size, sensors, litter, app and five-year running costs, plus who should buy which and a middle pick. - Source: https://selfcleaninglitterboxguide.com/posts/litter-robot-4-vs-petkit-puramax-2/ - Markdown version: https://selfcleaninglitterboxguide.com/posts/litter-robot-4-vs-petkit-puramax-2.md - Last updated: 2026-11-12 --- - [Home](https://selfcleaninglitterboxguide.com/) - [Guides](https://selfcleaninglitterboxguide.com/guides/) - Litter-Robot 4 vs PETKIT PuraMax 2: Is the Extra $300 Worth It? Head-to-head # Litter-Robot 4 vs PETKIT PuraMax 2: Is the Extra $300 Worth It? Updated November 12, 2026 By [Self-Cleaning Litter Box Guide Editorial Team](https://selfcleaninglitterboxguide.com/about/) [How we research](https://selfcleaninglitterboxguide.com/how-we-research/) Prices are approximate and change often, so check the current price before you buy. ## Key takeaways - The **Litter-Robot 4** is the stronger machine: rated for up to four cats from 3 to 25 lb, a 15.75 × 15.75 in entry, laser and weight sensors and the app reviewers like most. It costs about $699–749. - The **PETKIT PuraMax 2** costs about $390–400 and keeps its entrance open while the drum turns, but its entry is small. WIRED's 17-lb cat found it cramped. - Both pass the most important safety check: **neither closes the entrance during a cycle**. Minimums are 3 lb (Whisker) and 3.3 lb (PETKIT); smaller kittens need automatic mode off. - With our default assumptions, five years with one cat costs about **$1,580 for the LR4** and **$990 for the PuraMax 2**, box included. - If your cat is big but your budget isn't, the **Purobot Max Pro 2** (about $500–550) has a 43% larger entry than earlier PETKIT boxes and was WIRED's favorite. ## Our top picks - 1![Whisker Litter-Robot 4](https://selfcleaninglitterboxguide.com/_astro/whisker-litter-robot-4.CZhanV3w_12M27U.webp)Best for big cats and up to four cats: laser and weight sensors, 15.75 in entry, about $699–749[Whisker Litter-Robot 4](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/)Rotating globe · 3–25 lb · up to 4 cats8.7**$$$**$PremiumPrice tier: Premium[Check price on Amazon](https://www.amazon.com/dp/B0BH6MD3DJ?tag=selfcleaninglitterboxguide.com-20) - 2Best value for average-size cats: entrance stays open while cycling, about $390–400[PETKIT PuraMax 2](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-puramax-2/)Tilting drum · 3.3–22 lb · cats: not stated8.5**$$**$$Mid-rangePrice tier: Mid-range[Check price](https://www.amazon.com/dp/B0DFYF2D7D?tag=selfcleaninglitterboxguide.com-20) - 3![PETKIT Purobot Max Pro 2](https://selfcleaninglitterboxguide.com/_astro/petkit-purobot-max-pro-2.tJpodhLt_Zt19WQ.webp)The in-between pick: 43% larger PETKIT entry plus a camera, about $500–550[PETKIT Purobot Max Pro 2](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-purobot-max-pro-2/)Tilting drum · 3.3–22 lb · cats: not stated8.6**$$**$$Mid-rangePrice tier: Mid-range[Check price](https://www.amazon.com/dp/B0DFYLFFG1?tag=selfcleaninglitterboxguide.com-20) ### On this page 12 sections - [Litter-Robot 4 vs PuraMax 2 specs](#litter-robot-4-vs-puramax-2-specs) - [Entry size decides it for big cats](#entry-size-decides-it-for-big-cats) - [Safety: both keep the entrance open](#safety-both-keep-the-entrance-open) - [Multi-cat homes](#multi-cat-homes) - [Litter and odor](#litter-and-odor) - [App and daily use](#app-and-daily-use) - [Long-term reliability](#long-term-reliability) - [Running costs](#running-costs) - [The in-between option: Purobot Max Pro 2](#the-in-between-option-purobot-max-pro-2) - [Who should buy which](#who-should-buy-which) - [Verdict](#verdict) - [FAQ](#faq) ## Before you choose - [Litter-Robot Alternatives That Are Worth It (and Two to Skip)](https://selfcleaninglitterboxguide.com/posts/litter-robot-alternatives/) - [The 8 Best Self-Cleaning Litter Boxes of 2026, Ranked for Safety and Value](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-boxes-2026/) - [The Best Self-Cleaning Litter Box for Large Cats in 2026](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-box-for-large-cats/) The [Litter-Robot 4](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/) is the better machine, and the [PETKIT PuraMax 2](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-puramax-2/) is the better value for most homes with one or two average-size cats. The Litter-Robot 4 costs about $699–749 and is built for bigger cats and bigger households. The PuraMax 2 costs about $390–400, keeps its entrance open while it cleans, and gives up entry size, app polish and a cats-per-unit rating to get there. We haven’t tested either box ourselves. This comparison uses maker specs from Whisker and PETKIT, Amazon listing text and hands-on reviews from WIRED, Tom’s Guide and Cats.com, and we name the outlet wherever a test result appears. Prices are typical street prices from dated sources, not live Amazon prices, so check today’s price before you buy. ## Litter-Robot 4 vs PuraMax 2 specs | | [Litter-Robot 4](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/) | [PETKIT PuraMax 2](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-puramax-2/) | | --- | --- | --- | | Typical price | About $699–749 | About $390–400 | | Cat weight (maker) | 3–25 lb | 3.3–22 lb in PETKIT’s FAQ (WIRED lists 3.5–18 lb) | | Cats per unit | Up to 4 (Whisker) | No number given | | Entry | 15.75 × 15.75 in | 10.04 × 7.87 in (PETKIT); WIRED measured 7.87 × 8.85 in | | Footprint | 22 × 27 in, about 29.5 in tall | 24.4 × 21.2 in, 21.7 in tall | | Sensors | Laser curtain plus weight sensors | 11 sensors, including proximity and weight | | Entry stays open while cycling | Yes | Yes (anti-pinch design, per PETKIT) | | Litter | Clumping clay; white or translucent litter can confuse the level sensor | Clay, tofu, mixed or bentonite; not crystal | | Waste bin | As rarely as once every 8 days (Whisker) | 7 L, up to 15 days for one cat (PETKIT lab claim) | | App | Whisker app; tracks visits, weight, litter level and drawer | PETKIT app; no litter-level sensor, ads (WIRED) | | Wi-Fi | Wi-Fi | 2.4 GHz | | Warranty | 1-year WhiskerCare; 3-year extended plan available | 2-year coverage in the Amazon listing title | The [comparison chart](https://selfcleaninglitterboxguide.com/litter-boxes/) has the same specs for every box we cover. ## Entry size decides it for big cats The biggest physical difference is the doorway. The Litter-Robot 4’s entry is 15.75 in square, with 16.5 in of headroom inside, according to Whisker. PETKIT gives the PuraMax 2’s entrance as 255 × 200 mm, about 10 × 7.9 in, and WIRED measured 7.87 × 8.85 in. That gap shows up in testing. WIRED’s 17-lb cat found the PuraMax 2’s opening cramped. PETKIT’s FAQ rates the box for cats from 3.3 to 22 lb, but PETKIT’s own buying guide says up to 18 lb, and WIRED lists 3.5 to 18 lb. When a maker’s figures disagree, use the lower one. We’d treat about 15 lb as the comfortable ceiling for the PuraMax 2. The Litter-Robot 4 is rated for 3 to 25 lb, and Tom’s Guide notes an elevated step and an interior night light. If your cat is long-bodied or over 15 lb, enter their weight in the [safety checker](https://selfcleaninglitterboxguide.com/tools/cat-safety-checker/#weight=17&model=petkit-puramax-2) before choosing, and read our [large-cat guide](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-box-for-large-cats/). Which cat weights each box allows (lb) Maker ranges for automatic mode. Below the left end, the sensors may not notice your cat; hatched bars have no published minimum. Hooded globe / drum Open-top Rake / other [Leo's Loo Too 1–20](https://selfcleaninglitterboxguide.com/litter-boxes/casa-leo-leos-loo-too/)[Neakasa M1 2.2–33](https://selfcleaninglitterboxguide.com/litter-boxes/neakasa-m1/)[ScoopFree SmartSpin 2.5–25](https://selfcleaninglitterboxguide.com/litter-boxes/petsafe-scoopfree-smartspin/)[Litter-Robot 5 3–30](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-5/)[Litter-Robot 4 3–25](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/)[Litter-Robot EVO 3–19](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-evo/)[Purobot Ultra 3.3–22](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-purobot-ultra/)[Purobot Max Pro 2 3.3–22](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-purobot-max-pro-2/)[PuraMax 2 3.3–22](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-puramax-2/)[Furbulous Self-Packing 3.3–22](https://selfcleaninglitterboxguide.com/litter-boxes/furbulous-self-packing/)[Lesure Open-Top 3.3–18](https://selfcleaninglitterboxguide.com/litter-boxes/lesure-open-top/)[ELS PET Orbitie ?–21](https://selfcleaninglitterboxguide.com/litter-boxes/els-pet-orbitie/)[ScoopFree Classic ?–15](https://selfcleaninglitterboxguide.com/litter-boxes/petsafe-scoopfree-crystal-classic/)[ScoopFree Crystal Smart ?–?](https://selfcleaninglitterboxguide.com/litter-boxes/petsafe-scoopfree-crystal-smart/) 05101520253035 Kittens under the minimum should use the box with automatic cleaning off. Check your own cat in the [safety checker](https://selfcleaninglitterboxguide.com/tools/cat-safety-checker/). ## Safety: both keep the entrance open This is where the two are closest. The Litter-Robot 4 is one of WIRED’s picks, and WIRED only recommends boxes that stay open during cycling. PETKIT says the PuraMax 2’s anti-pinch design keeps the entrance open as the drum rotates, and Cats.com confirms the drum doesn’t turn fully. The sensors differ. Whisker pairs a laser curtain with weight sensors, so the globe has two independent ways to notice a cat. PETKIT lists 11 xSecure sensors, including proximity and weight. Both stop the cycle when a cat is detected. Placement matters with weight sensors. Cats.com’s tester turned the PuraMax 2’s auto-scoop off when it sat on carpet, because the weight sensor became inaccurate. Put either box on a hard, level floor. ### Kittens and small cats - **Litter-Robot 4:** Whisker says a kitten under 3 lb should use the box powered off, with cycles started by hand, until it reaches 3 lb. - **PuraMax 2:** PETKIT gives 3.3 lb as the minimum for automatic mode. Either way, keep a regular box out until the kitten is over the minimum and using the robot reliably. Our [kitten guide](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-box-for-kittens/) and [safety explainer](https://selfcleaninglitterboxguide.com/posts/are-self-cleaning-litter-boxes-safe/) cover the details. ## Multi-cat homes Whisker rates the Litter-Robot 4 for up to four cats. PETKIT sells the PuraMax 2 as a multi-cat box but gives no number. For three or four cats, that rating is worth paying for. Tom’s Guide found the LR4’s app tells cats apart by weight, which helps when you want to know who is using the box. PETKIT’s bag listing suggests changing bags twice a week for two average-size cats, so plan for frequent emptying with more. Even with a robot, don’t drop to one box for a crowd. The AAFP’s guidance for regular boxes is one per cat plus one, and WIRED suggests keeping the old box out during the switch. Our [box calculator](https://selfcleaninglitterboxguide.com/tools/how-many-litter-boxes/#cats=3&auto=1) and the [multi-cat guide](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-box-for-multiple-cats/) go further. ## Litter and odor The Litter-Robot 4 wants standard-weight clumping clay. Whisker notes that white or translucent litter can confuse the litter-level sensor. A clay litter such as [Dr. Elsey’s Ultra](https://www.amazon.com/dp/B0009X29WK?tag=selfcleaninglitterboxguide.com-20) is a common choice. Odor control is a sealed drawer with a carbon filter, plus optional OdorTrap packs, and Whisker suggests replacing both every 2–4 weeks. The PuraMax 2 is more flexible. WIRED says it handles clay, tofu, mixed and bentonite litters, but not crystal. It uses triple odor control, and WIRED found it smelled neutral or even good. The box ships with an N50 odor eliminator and 20 bags, according to the Amazon listing, and an N50 refill lasts about a month. If you want tofu litter, the PuraMax 2 is the easier fit. See our [litter guide](https://selfcleaninglitterboxguide.com/posts/best-litter-for-self-cleaning-litter-boxes/) and the [accessories page](https://selfcleaninglitterboxguide.com/accessories/) for refills. ## App and daily use WIRED likes Whisker’s app. It tracks visits and weight and warns when litter is low or the drawer is full. The optional LitterHopper ($129 at Whisker) refills litter automatically, which is why WIRED names the LR4 its pick for litter refilling. The PuraMax 2 has no litter-level sensor, so you check and top up by hand. WIRED found PETKIT’s app crowded with ads and sometimes buggy. It needs 2.4 GHz Wi-Fi. PETKIT claims 35 dB in operation. ## Long-term reliability The Litter-Robot 4 has the longer test record, and it isn’t spotless: - **WIRED:** after nearly two years, its unit sometimes sensed “ghost cats” and reported a full drawer when it was half full. The LitterHopper intermittently stopped working in the long-term test. - **Tom’s Guide:** used for more than a year and still holding up, but it sometimes squeaked while cleaning, so it needs regular maintenance. It could also still cycle when the app said the bin was full. Cats.com rated the PuraMax 2 3.8 out of 5 and found the empty-all-litter function struggled. On warranty, the PuraMax 2’s Amazon listing title advertises 2-year coverage, while a PETKIT article says 1 year, so confirm the terms on the listing. Whisker gives 1 year of WhiskerCare and sells a 3-year extended plan. Our [troubleshooting guide](https://selfcleaninglitterboxguide.com/posts/automatic-litter-box-troubleshooting/) covers ghost-cat and drawer-full errors. ## Running costs Neither box is expensive to run, but the Litter-Robot 4 costs more each month. These are our default assumptions, not measured figures: about 10 lb of clumping litter per cat per month at Dr. Elsey’s Chewy price ($0.57 a pound), plus the maker’s consumables. | One cat, default assumptions | Litter-Robot 4 | PuraMax 2 | | --- | --- | --- | | Consumables | Liners ($25 for 25) and one $5 carbon filter a month | About 4.3 bags a month at a $1 stand-in price | | Per year with litter | About $177 | About $121 | | Five years, box included | About $1,580 | About $990 | | Five years, two cats | About $2,470 | About $1,600 | We couldn’t confirm PETKIT’s own bag price, so the PuraMax 2 figure uses Whisker’s $1-per-liner price as a stand-in. Third-party packs are usually cheaper. Optional OdorTrap packs and N50 refills are excluded. Put your own numbers into the [cost calculator](https://selfcleaninglitterboxguide.com/tools/litter-box-cost-calculator/#cats=2&years=5). Five-year cost for 1 cat Lowest typical box price + maker-priced liners, filters or trays + clumping litter (10 lb per cat per month at $0.57/lb). Optional extras excluded. Hooded globe / drum Open-top Rake / other [ScoopFree SmartSpin $780](https://selfcleaninglitterboxguide.com/litter-boxes/petsafe-scoopfree-smartspin/)[Lesure Open-Top $850](https://selfcleaninglitterboxguide.com/litter-boxes/lesure-open-top/)[ELS PET Orbitie $860](https://selfcleaninglitterboxguide.com/litter-boxes/els-pet-orbitie/)[Furbulous Self-Packing $920](https://selfcleaninglitterboxguide.com/litter-boxes/furbulous-self-packing/)[Neakasa M1 $960](https://selfcleaninglitterboxguide.com/litter-boxes/neakasa-m1/)[PuraMax 2 $990](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-puramax-2/)[Purobot Max Pro 2 $1.1k](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-purobot-max-pro-2/)[Leo's Loo Too $1.2k](https://selfcleaninglitterboxguide.com/litter-boxes/casa-leo-leos-loo-too/)[Litter-Robot EVO $1.5k](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-evo/)[ScoopFree Classic $1.6k](https://selfcleaninglitterboxguide.com/litter-boxes/petsafe-scoopfree-crystal-classic/)[Litter-Robot 4 $1.6k](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/)[ScoopFree Crystal Smart $1.7k](https://selfcleaninglitterboxguide.com/litter-boxes/petsafe-scoopfree-crystal-smart/)[Litter-Robot 5 $1.7k](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-5/)[Purobot Ultra $1.8k](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-purobot-ultra/) 05001k1.5k2k Crystal-tray boxes include litter in the tray price. Change any assumption in the [cost calculator](https://selfcleaninglitterboxguide.com/tools/litter-box-cost-calculator/). Supplies, if you go either way: [Whisker liners](https://www.amazon.com/dp/B0F3QTK9ZT?tag=selfcleaninglitterboxguide.com-20), [LR4 carbon filters](https://www.amazon.com/dp/B0BMNB1C7K?tag=selfcleaninglitterboxguide.com-20), [PETKIT bags](https://www.amazon.com/dp/B0DK3KDMW1?tag=selfcleaninglitterboxguide.com-20) and the [N50 three-pack](https://www.amazon.com/dp/B0D8429H9Y?tag=selfcleaninglitterboxguide.com-20). ## The in-between option: Purobot Max Pro 2 If you like PETKIT’s price but your cat is too big for the PuraMax 2, look at the [Purobot Max Pro 2](https://selfcleaninglitterboxguide.com/litter-boxes/petkit-purobot-max-pro-2/). It is WIRED’s current favorite. Its entrance is 10.51 × 10.74 in, which PETKIT says is 43% larger than the previous generation, and WIRED’s 17-lb cat used it easily. It adds a 1080p, 210° camera that recognizes cats and records visits. PETKIT claims an 8 L bin that lasts up to 17 days for one cat, and it supports 2.4 and 5 GHz Wi-Fi. The weight range is 3.3–22 lb, the same as the PuraMax 2. The trade-offs: the entry sits about 10 in off the floor, a step up for stiff senior cats. WIRED found the app still crowded with ads, and for some testers cat ID got confused after the free Care+ trial ended. At about $500–550, it still costs well under a Litter-Robot 4. [Check the Purobot Max Pro 2 price](https://www.amazon.com/dp/B0DFYLFFG1?tag=selfcleaninglitterboxguide.com-20). ## Who should buy which | Your situation | Buy | | --- | --- | | One or two cats under about 15 lb, budget matters | [PuraMax 2](https://www.amazon.com/dp/B0DFYF2D7D?tag=selfcleaninglitterboxguide.com-20) | | You want tofu or mixed litter | PuraMax 2 | | Cat over 15 lb, or long-bodied | [Litter-Robot 4](https://www.amazon.com/dp/B0BH6MD3DJ?tag=selfcleaninglitterboxguide.com-20) or Purobot Max Pro 2 | | Three or four cats | Litter-Robot 4 | | You want automatic litter refilling | Litter-Robot 4 with the LitterHopper | | You want a camera on every visit | [Purobot Max Pro 2](https://www.amazon.com/dp/B0DFYLFFG1?tag=selfcleaninglitterboxguide.com-20) | | Kitten under 3 lb | Either, with automatic mode off until it’s big enough | Not sure? The [litter box matcher](https://selfcleaninglitterboxguide.com/tools/litter-box-matcher/#cats=2&budget=600) takes your cats and budget and narrows the list. If neither fits, our [Litter-Robot alternatives](https://selfcleaninglitterboxguide.com/posts/litter-robot-alternatives/) guide covers open-top and crystal-tray options, and [Litter-Robot 5 vs 4 vs EVO](https://selfcleaninglitterboxguide.com/posts/litter-robot-5-vs-litter-robot-4-vs-evo/) compares the Whisker range. ## Verdict Buy the PETKIT PuraMax 2 if you have one or two average-size cats and want the best value among well-reviewed boxes. It keeps its entrance open, handles more litter types and costs about half as much. Accept topping up litter by hand and a cluttered app. Buy the Litter-Robot 4 if you have a big cat, three or four cats, or you want the best app and automatic refilling. It has the larger entry, a laser curtain on top of weight sensors and Whisker’s support behind it. Budget for upkeep as it ages. If you sit between the two, the Purobot Max Pro 2 gives big cats room to move for about $200 less than a Litter-Robot 4. Whichever you pick, [check today’s Litter-Robot 4 price](https://www.amazon.com/dp/B0BH6MD3DJ?tag=selfcleaninglitterboxguide.com-20) or [PuraMax 2 price](https://www.amazon.com/dp/B0DFYF2D7D?tag=selfcleaninglitterboxguide.com-20), keep your old box out during the switch, and follow our [transition guide](https://selfcleaninglitterboxguide.com/posts/how-to-transition-cat-to-automatic-litter-box/). ## Don't guess. Calculate. - [🐾 Safety checker](https://selfcleaninglitterboxguide.com/tools/cat-safety-checker/): which boxes fit your cat - [💵 Cost calculator](https://selfcleaninglitterboxguide.com/tools/litter-box-cost-calculator/): 1-, 3- and 5-year totals - [🎯 Litter box matcher](https://selfcleaninglitterboxguide.com/tools/litter-box-matcher/): ranked for your home - [📊 Compare every box](https://selfcleaninglitterboxguide.com/litter-boxes/): sortable spec table ## Frequently asked questions ### Is the Litter-Robot 4 better than the PETKIT PuraMax 2? It is the more capable box. Whisker rates the Litter-Robot 4 for up to four cats from 3 to 25 lb, its entry is 15.75 × 15.75 in, and it combines a laser curtain with weight sensors. The PuraMax 2 is about half the price and keeps its entrance open while cycling, so for one or two average-size cats it is the better value. WIRED calls the PuraMax 2 the best option for most people and the LR4 the best pick if you want automatic litter refilling. ### Can a large cat use the PETKIT PuraMax 2? PETKIT's FAQ says 3.3 to 22 lb, but PETKIT's own buying guide says up to 18 lb and WIRED lists 3.5 to 18 lb. The entry is about 10 × 7.9 in by PETKIT's measurements, and WIRED's 17-lb cat found it cramped. For a cat over about 15 lb, the Litter-Robot 4 or the Purobot Max Pro 2 is the safer fit. ### Do the Litter-Robot 4 and PuraMax 2 stay open while cleaning? Yes. The Litter-Robot 4 is one of WIRED's picks, and WIRED only recommends boxes that stay open during cycling. PETKIT says the PuraMax 2's anti-pinch design keeps the entrance open during rotation, and Cats.com confirms the drum doesn't turn fully. ### Which is cheaper to run, the Litter-Robot 4 or the PuraMax 2? On our default assumptions the PuraMax 2 is cheaper: about $121 a year for one cat in bags and litter against about $177 for the Litter-Robot 4's liners, carbon filters and litter. PETKIT's bag price is our stand-in, so enter your own prices in the cost calculator. ### Can kittens use either box? Not in automatic mode until they reach the minimum weight. Whisker says to leave the Litter-Robot 4 powered off and cycle it yourself until a kitten weighs 3 lb. PETKIT gives 3.3 lb as the PuraMax 2's minimum for automatic mode. Keep a regular box available in the meantime. ## Sources - [Whisker: Litter-Robot 4](https://www.litter-robot.com/litter-robot-4.html) · checked 2026-11-12 — 3–25 lb cats, up to 4 cats, 15.75 × 15.75 in entry, 22 × 27 in footprint, laser and weight sensors, kittens under 3 lb in semi-automatic mode, carbon filter and OdorTrap every 2–4 weeks, $699. - [PETKIT: PuraMax 2](https://www.petkit.com/products/petkit-puramax-2) · checked 2026-11-12 — 3.3–22 lb in the FAQ, 200 mm entrance height, 7 L bin up to 15 days for one cat (lab), 35 dB, 11 xSecure sensors, anti-pinch design keeps the entrance open during rotation. - [PETKIT: Purobot Max Pro 2](https://www.petkit.com/products/purobot-max-pro-2-automatic-cat-litter-box-with-ai-camera) · checked 2026-11-12 — Entrance 10.51 × 10.74 in (43% wider), 3.3–22 lb, 8 L bin up to 17 days, 12 safety sensors, 1080p 210° camera. - [WIRED: The Best Automatic Litter Boxes](https://www.wired.com/gallery/best-automatic-cat-litter-boxes/) · checked 2026-11-12 — PuraMax 2 best for most people ($390 Amazon; 17-lb cat found it cramped; no litter-level sensor; ad-crowded app); Purobot Max Pro 2 new favorite; LR4 best with litter refilling, ghost-cat errors after about two years. - [Cats.com: PETKIT PuraMax 2 review](https://cats.com/petkit-puramax-2-automatic-litter-box-review) · checked 2026-11-12 — Rated 3.8/5; entrance always open and drum doesn't turn fully; tester turned auto-scoop off on carpet because the weight sensor became inaccurate. - [Tom's Guide: I asked cats to test these robotic litter boxes](https://www.tomsguide.com/home/smart-home/my-cats-have-tested-these-robotic-litter-boxes-for-months-heres-the-one-they-use-the-most) · checked 2026-11-12 — Litter-Robot 4 used for more than a year and still holding up; sometimes squeaks, so maintenance is needed; app tells cats apart by weight. - [Whisker: Litter-Robot waste drawer liners](https://www.litter-robot.com/litter-robot-waste-drawer-liners.html) · checked 2026-11-12 — Liners cost $25 for 25. - [Whisker: Litter-Robot 4 carbon filters](https://www.litter-robot.com/litter-robot-4-carbon-filters.html) · checked 2026-11-12 — Carbon filters cost $30 for 6; Whisker says one filter per cat. - [Amazon: PETKIT PuraMax 2 listing](https://www.amazon.com/dp/B0DFYF2D7D?tag=selfcleaninglitterboxguide.com-20) · checked 2026-11-12 — Listing title advertises 2-year coverage; 3.3–22 lb; waste bin up to 15 days; 2.4 GHz Wi-Fi; includes N50 2.0 and 20 bags. ## Get new guides by e-mail One short e-mail when Self-Cleaning Litter Box Guide publishes a new guide. No spam, no sharing your address, and you can unsubscribe in one click. E-mail address New posts only · Unsubscribe anytime · [Privacy](https://selfcleaninglitterboxguide.com/privacy/) Our #1 pick Best for big cats and up to four cats: laser and weight sensors, 15.75 in entry, about $699–749 ![Whisker Litter-Robot 4](https://selfcleaninglitterboxguide.com/_astro/whisker-litter-robot-4.CZhanV3w_VBSjy.webp) ### [Whisker Litter-Robot 4](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/) 8.7 - Rotating globe - 3–25 lb - Up to 4 cats - Entry stays open Multi-cat homes (up to four cats) and big cats that want the best-supported, most-copied design on the market. $$$$ Premium Price tier: Premium typical street price; check Amazon for today's [Check price on Amazon](https://www.amazon.com/dp/B0BH6MD3DJ?tag=selfcleaninglitterboxguide.com-20)[Read the full review](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/) [🐾 Safe for your cat? Check weight limits, kitten rules and cats per box in 20 seconds.](https://selfcleaninglitterboxguide.com/tools/cat-safety-checker/)[💵 What will it really cost? Liners, trays and litter over five years, model by model.](https://selfcleaninglitterboxguide.com/tools/litter-box-cost-calculator/) ## Keep reading [Alternatives ### Litter-Robot Alternatives That Are Worth It (and Two to Skip) The Litter-Robot alternatives worth buying in 2026: PETKIT PuraMax 2 and Max Pro 2, Neakasa M1, Lesure and ScoopFree, plus two designs we'd skip, and why. Updated Nov 12, 2026](https://selfcleaninglitterboxguide.com/posts/litter-robot-alternatives/)[Top picks ### The 8 Best Self-Cleaning Litter Boxes of 2026, Ranked for Safety and Value The best self-cleaning litter boxes of 2026, ranked: Litter-Robot 4, PETKIT PuraMax 2, Purobot Max Pro 2, Neakasa M1 and more, with safety and cost notes. Updated Nov 12, 2026](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-boxes-2026/)[Large cats ### The Best Self-Cleaning Litter Box for Large Cats in 2026 The best self-cleaning litter boxes for big cats, compared on what matters: maker weight limits, entry size, interior height, step-up height and open tops. Updated Nov 12, 2026](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-box-for-large-cats/) Best for big cats and up to four cats: laser and weight sensors, 15.75 in entry, about $699–749 Litter-Robot 4 $$$$ Premium Price tier: Premium [Check price](https://www.amazon.com/dp/B0BH6MD3DJ?tag=selfcleaninglitterboxguide.com-20)