Whisker Litter-Robot 4 vs Whisker Litter-Robot EVO

Both makers say their sensor detects cats from 3 lb, so the kitten threshold does not separate them. For a large cat, the Whisker Litter-Robot 4 is rated to 25 lb and the Whisker Litter-Robot EVO to 19. Every other published figure for both is in the table, with the rows where they differ tinted.

Whisker Litter-Robot 4 self-cleaning litter box

Whisker

Whisker Litter-Robot 4

Automate from ~3 lb / ~3 monthsAnti-pinch protection

~$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

Days between emptying

The maker publishes no drawer volume, so the days cannot be worked out. Its own claim is up to 8 days for one cat.

Whisker Litter-Robot EVO self-cleaning litter box

Whisker

Whisker Litter-Robot EVO

Automate from ~3 lb / ~3 months

~$599

Whisker's entry model shrinks the globe to fit a 20.6-by-24.3-inch spot and drops the curtain lasers: its own FAQ says it relies on weight sensors to know a cat is inside.

Best for: One or two average-size cats in an apartment

Days between emptying

The maker publishes no drawer volume, so the days cannot be worked out. Its own claim is up to 7 days for one cat.

Specification comparison of the Whisker Litter-Robot 4 and the Whisker Litter-Robot EVO
SpecificationWhisker Litter-Robot 4Whisker Litter-Robot EVO
Approx. price~$699~$599
TypeRotating drumRotating drum
Kitten gateAutomate from ~3 lb / ~3 monthsAutomate from ~3 lb / ~3 months
Min. detection weight3 lb3 lb
Max. cat weight25 lb19 lb
Big-cat fitRated for large breeds (to 25 lb)Small to medium cats (to 19 lb)
Entry opening15.75 × 15.75 in14.85 × 14.85 in
Entry step6.9 in off the floor5.6 in off the floor
Interior height16.5 in14.5 in
Footprint22 × 27 in × 29.5 in tall20.6 × 24.3 in × 27.6 in tall
Maker's drawer claimUp to 8 days, one catUp to 7 days, one cat
Cats supportedUp to 4Up to 2
Litter systemClumping litterClumping litter
Litters listedclumping clayclumping clay
Litters to avoidtofu, clumping wood/pine, non-clumping, paper, pellets, silica crystaltofu, clumping wood/pine, non-clumping, paper, pellets, silica crystal
Weight sensorYesYes
Anti-pinch protectionStated by the makerNot stated by the maker
Infrared / radarYesNo
CameraNoNo
Wi-Fi appYesYes
Running costNo required consumableNo required consumable
Bags / linersStandard trash bag or Whisker's custom-fit drawer linersWhisker custom-fit drawer liners ($25 for 25)
Warranty1 year1 year
First listed20222025

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

Whisker Litter-Robot EVO: what it gives up

  • Weight is the only detection method Whisker describes; there are no curtain lasers
  • 19 lb ceiling and 14.5-inch interior rule out the largest cats
  • Rated for two cats at most
  • Shortest emptying estimate of the Whisker range, about seven days for one cat
  • 2.4 GHz Wi-Fi only

Full pages: Whisker Litter-Robot 4 · Whisker Litter-Robot EVO