Whisker Litter-Robot 4 vs PETKIT Purobot Max 3
The Whisker Litter-Robot 4 detects lighter cats: 3 lb against 3.3 lb for the PETKIT Purobot Max 3, which matters most in a home with a kitten on the way. For a large cat, the Whisker Litter-Robot 4 is rated to 25 lb and the PETKIT Purobot Max 3 to 22. Every other published figure for both is in the table, with the rows where they differ tinted.
Whisker
Whisker Litter-Robot 4
~$699
Four years on, this is still the reference point everything else in the category gets measured against.
Best for: Two or three average cats in a home that already uses clay clumping litter
The maker publishes no drawer volume, so the days cannot be worked out. Its own claim is up to 8 days for one cat.
PETKIT
PETKIT Purobot Max 3
~$400
PETKIT's third-generation drum, and the model its US store now redirects to from the old PuraMax 2 page.
Best for: One or two cats under 22 lb, especially older cats that struggle with a high step
- 1 cat
- ~10
- days
- 2 cats
- ~5
- days
- 3 cats
- ~3
- days
| Specification | Whisker Litter-Robot 4 | PETKIT Purobot Max 3 |
|---|---|---|
| Approx. price | ~$699 | ~$400 |
| Type | Rotating drum | Rotating drum |
| Kitten gate | Automate from ~3 lb / ~3 months | Automate from ~3.3 lb / ~6 months |
| Min. detection weight | 3 lb | 3.3 lb |
| Maker's minimum age | not published | 6 months |
| Max. cat weight | 25 lb | 22 lb |
| Big-cat fit | Rated for large breeds (to 25 lb) | Rated to 22 lb — short of the heaviest large breeds |
| Entry opening | 15.75 × 15.75 in | 10.51 × 10.74 in |
| Entry step | 6.9 in off the floor | 8.03 in off the floor |
| Interior height | 16.5 in | not published |
| Footprint | 22 × 27 in × 29.5 in tall | 24.4 × 21.2 in × 21.7 in tall |
| Drawer volume | not published | 7 L |
| Days between emptying | not published | ~10 / 5 / 3 days for 1 / 2 / 3 cats |
| Maker's drawer claim | Up to 8 days, one cat | Up to 15 days, one cat |
| Cats supported | Up to 4 | not published |
| Litter system | Clumping litter | Clumping litter |
| Litters listed | clumping clay | clumping clay, tofu, mixed |
| Litters to avoid | tofu, clumping wood/pine, non-clumping, paper, pellets, silica crystal | non-clumping |
| Weight sensor | Yes | Yes |
| Anti-pinch protection | Stated by the maker | Stated by the maker |
| Infrared / radar | Yes | Yes |
| Camera | No | No |
| Wi-Fi app | Yes | Yes |
| Running cost | No required consumable | No required consumable |
| Bags / liners | Standard trash bag or Whisker's custom-fit drawer liners | PETKIT automatic litter box trash bags ($29.99 for 5 rolls) |
| Warranty | 1 year | 2 years |
| First listed | 2022 | 2026 |
Whisker Litter-Robot 4: what it gives up
- Whisker publishes no drawer volume, only an 'about every 8 days for one cat' estimate
- Needs 2.4 GHz Wi-Fi; 5 GHz networks are not supported
- Plant-based, pine, pellet and white crystal litters are all on the do-not-use list
- At 22 by 27 inches it wants a floor spot bigger than most ordinary boxes
PETKIT Purobot Max 3: what it gives up
- Two conflicting noise figures on the maker's own page
- 22 lb ceiling
- A 7-litre bin is a litre smaller than the Max Pro 2's
- Joins 2.4 GHz Wi-Fi only
Full pages: Whisker Litter-Robot 4 · PETKIT Purobot Max 3