Litter-Robot 4 Review: $100 Above the EVO, $100 Below the 5

What the $100 up to the Litter-Robot 5 adds

On Whisker's comparison table the $799 Litter-Robot 5 is rated for five cats at 3-30 lb, where the 4 is rated for four at 3-25 lb. The 5's interior globe is 17.5 inches tall against the 4's 16.5. Its drawer is quoted at about 10 days for one cat against eight, and it weighs 28.7 lb empty against 24. The 5 Pro matches the 5 on capacity, drawer interval and globe height, puts 29.6 lb on the scale against 28.7, and charges another $100 for an integrated pair of cameras, which the Pro's page describes as dual 1080p cameras with night vision and facial recognition unlocked through a Whisker+ membership.

WasteID is the sensor row the table checks on the 5 and the 5 Pro and leaves blank on the 4; the only other row split the same way is Bezel Guard. Whisker's 5 page says WasteID distinguishes urine from feces, which is what the targeted odor handling and the routine monitoring are built on. All four list an LED control panel and status lights, and the table leaves the color LCD unchecked on the 4 alone, where the 5, the 5 Pro and the cheaper EVO show a screen. So the extra $100 buys WasteID and a color screen, an inch more globe height, a fifth cat and five more pounds of weight allowance.

What the $100 down to the EVO gives up, and what it keeps

Every dimension Whisker publishes shrinks on the $599 EVO. Footprint drops to 20.6 by 24.3 inches from 22 by 27. Exterior height falls to 27.6 inches from 29.5, the opening to 14.85 inches from 15.75, the interior globe to 14.5 inches from 16.5, and the step to 5.6 inches from 6.9. It weighs 21.5 lb, which is 2.5 lb less to move when you clean behind it.

Sensing is where the saving shows. The table bills the EVO's waste level sensing as "only notifies when full" against "monitors any level" on the 4, and it leaves the EVO unchecked for LitterLevel, for LitterHopper and OdorTrap Holder support, for the scratch-resistant globe liner and for the adjustable night light. Its drawer is quoted at about seven days for one cat against eight. Two rows run against that grain. The EVO lists a built-in carpet tray where the 4 needs the $30 add-on, and the EVO is quoted as usable on "any type of flooring". Whisker also limits EVO sales and shipping to the US and Canada.

Which cat ends up in which box

Weight sorts most households before anything else does. The EVO stops at 19 lb and two cats. The 4 reaches 25 lb and four. The 5 and the 5 Pro reach 30 lb and five. A cat over 19 lb rules out the smallest machine on paper, and so does a third cat, which leaves the 4 as the cheapest box that will hold either.

Step height is the second filter, and it runs against price. The EVO asks a cat to clear 5.6 inches, the 4 asks for 6.9 and the 5 asks for 7, so a senior cat with a shallow jump may find the cheapest of the three the easiest to enter. Door width runs the opposite direction, at 14.85 inches on the EVO against 15.75 on the rest. All four share the same 3 lb floor for automatic use, and under it Whisker asks for a supervised routine rather than a setting.

The bill after the box

The running costs are small and they recur. On 2026-09-25 Whisker listed ten waste drawer liners at $12, a 2-pack of carbon filters at $12, a 3-pack of OdorTrap packs at $15 and a 20 lb bag of GreatLitter at $30. The 4's page says to change the liner whenever the drawer is emptied and to refresh the carbon filter and the OdorTrap pack at two weeks to a month; the carbon filter page tightens that to monthly. Whisker quotes one cat at about eight days between empties, so a single-cat home is looking at roughly four liner changes a month, about $4.80 of bags.

The larger line items hide in the options. The Litter-Robot 4 LitterHopper is $129, and it needs a firmware update through the app before it will dispense. Ordering it with the robot moves the configuration from $699 to $828. The Carpet Tray is $30, Color Bezels are posted at $35 and the LitterTrap Mat is $50. The 3-year WhiskerCare plan is a further $129.

The app works without the subscription. The 4's page says a 7-day view of visits and individual cat weights comes with the machine, and Whisker's FAQ says SmartScale identification and weight tracking stay free without a membership. Whisker+ is optional at $7.99 a month or $79.90 a year after a 30-day trial, and it stretches history out to two years.

The carpet, the kitten, and the litter list

The placement caveat is easy to miss because it hides under a question about carpet rather than one about weight. SmartScale, the scale that assigns a weight to each cat, is "most accurate on a firm surface, not carpeting", and Whisker asks for the $30 Carpet Tray on carpet 3 mm or thicker or on uneven flooring. The 5, the 5 Pro and the EVO all list that tray as built in, and the 4 is the only one of the four that does not. The box runs either way. What suffers without the tray is the per-cat weight the app reports, which is one of the reasons to buy this machine at all.

Kittens carry a similar catch. Whisker puts the automatic-mode floor at 3 lb. Below that, the instruction is to leave the robot powered off, wait about seven minutes after a visit for the waste to clump, switch it on to run a single cycle, then switch it off again, and repeat until the kitten reaches 3 lb. Whisker calls it semi-automatic mode, and it is a routine you perform rather than a setting you choose.

Litter narrows further than the feature card's "use any clumping cat litter" suggests. Clumping clay is the recommendation, and GreatLitter is Whisker's own example of it. Silica beads and crystals can work when they pass the screen, but translucent or white crystal litter can throw off the litter level and drawer-full readings on the 4, so Whisker does not recommend it. Plant-based litter, non-clumping or loose-clumping litter, newspaper pellets and wood pellets are all on the do-not-use list. Whisker's acclimation figure of "over 95% of cats", drawn from stated reasons for returns over one year, is the maker's number and not a forecast for your cat.

Warranty, trial, and the cost of changing your mind

WhiskerCare covers every robot for one year at no cost, and the list is wider than a defect warranty: accidental damage, power surges, mechanical and electrical breakdowns and software support, with free shipping both ways and no deductible. The terms page adds natural disasters. The 3-year extension is $129 on the 4, $149 on the 5 and the 5 Pro, and $99 on the EVO.

The in-home trial runs 90 days from receipt and refunds what you paid rather than the round trip, and it covers only robots bought directly through Whisker.com, Litter-Robot.com or Litterbox.com; a unit bought elsewhere goes back through whoever sold it. Amazon had the Black 4 at the same $699 on 2026-09-25, sold by Spreetail, with returns handled by Amazon for 30 days. Return shipping is yours. Whisker will supply a FedEx label for a $60 deduction, a unit sent back dirty can cost another $75, and a return without an RMA number is disposed of instead of refunded. Litter is not refundable, and opened litter mats are not returnable either, so the $50 LitterTrap Mat is a decision that stops being reversible once the box is open.

One price detail sits on the color picker. Black over Black and White over White are the $699 builds, and Whisker flagged both as shipping in one to three days. Put a Black base under a White bezel, or either base under the Lilac, Fuchsia, Mint, Marble, Woodgrain and Grey stone bezels, and the same machine is $734.