Litter-Robot EVO vs 4: Which One to Buy

Price and what you actually pay in year one

The gap is $100 at checkout and about $106 over the first year. EVO: "As low as $599," no struck-through list price (litter-robot.com, 10/09/2026 and 10/14/2026). Litter-Robot 4: "As low as $699," no list price shown, on the same dates. Shipping is free for both except AK, HI, and PR; sales tax varies by state and is not in our totals. Neither needs a subscription: Whisker+ is optional, $7.99/month after a 30-day trial or $79.90/year, one plan for both.

Consumables are the same parts: Waste Drawer Liners 25 for $25, carbon filters 2 for $12, one filter lasting "approximately 1 month" (EVO manual p. 31; Litter-Robot 4 manual p. 30). The liner interval is where Whisker disagrees with itself. EVO: "up to 7 days" on the page, "Empty drawer every 8 days" in the use-and-care article, "once per week is usually sufficient" in manual p. 17. Litter-Robot 4: "as low as once every 8 days" on the page, "once per week" for one cat in manual p. 36. Using the 8-day figure for the EVO and the manual's week for the 4: about $119 a year against about $125, litter excluded because any clumping clay works in both. First year, before tax: about $718 for the EVO, about $824 for the 4. Price-first buyer: the EVO.

Waste drawer and odor control: claimed vs measured

Whisker rates the 4 for up to four and the EVO "for one to two cats"; neither page prints drawer volume. Litter-Robot 4: "as low as once every 8 days" (page); yourbestdigs.com (Bryan Vu, updated 07/11/2023, one cat, wheat litter) was "notified of a full waste drawer about once every 7-10 days for one cat." EVO: "up to 7 days" (page), "every 8 days" (use-and-care); not independently measured. The litter charge explains the ratings: "approximately 0.8 gallons (3L)" in the EVO (manual p. 11) against about 4 L in the 4 (manual p. 12).

Noise: Whisker prints no decibels, only "QuietSift." For the 4, yourbestdigs.com measured 40–55 dBA average and about 59 dBA peak at about 20 inches with a sound level meter (ambient 38 dBA). EVO: not independently measured; technomeow.com (02/25/2026) calls the cycles "nearly silent," vetstreet.com (Maranda Elswick, DVM, 01/16/2026, two cats, beta firmware) "much quieter than prior models," neither with a meter. More than two cats: the 4. One cat: either, and the EVO is $100 cheaper.

Cat weight, kittens and the entry

The EVO is rated 3–19 lb; the 4 is 3–25 lb on its page, and Whisker's own sources disagree on that ceiling. EVO manual p. 37: "The Litter-Robot EVO is suitable for cats that weigh between 3 and 19 pounds"; under 3 lb, semi-automatic mode. Litter-Robot 4 manual p. 5, in metric: "Always be sure any cat or kitten in your household that might use the Litter-Robot weighs at least 1.36 kg"; p. 34: "We do not recommend that kittens or cats that weigh less than 1.36 kg use the Litter-Robot in the unattended Automatic Mode." Whisker's support FAQ says "No, Litter-Robot 4 does not have a weight limit."

Entry: EVO 14.85 x 14.85 in, "Floor to globe 10.75"" (manual p. 7), interior height 14.5 in. Litter-Robot 4: 15.75 x 15.75 in, floor to entryway about 12 in (30.5 cm) with a step in the box (manual p. 10), interior height 16.5 in. A cat over 19 lb: the 4. A tight bathroom: the EVO, 1.4 in narrower and 2.7 in shallower (20.6 x 24.3 in against 22 x 27 in).

App, Whisker+ and what works offline

Same Whisker app, 4.8 of 5 over 148K App Store ratings as of 10/09/2026. SmartScale identification and weight tracking "stay free on the EVO, 4, 5, and 5 Pro" (Whisker+ page). Both need 2.4 GHz Wi-Fi. Offline, Whisker's FAQ says, without naming a model, "The Whisker app is not required for Litter-Robot to function—Litter-Robot will still work as a self-cleaning litter box even without WiFi" (litter-robot.com/faq.html, 10/14/2026); only the 4's manual documents a Wi-Fi switch. The EVO has an LCD screen and buttons (manual p. 20) and a semi-automatic mode from the power button, but no manual line about running without Wi-Fi.

Whisker calls the EVO "a more compact, streamlined version of the LR4": no LitterHopper option, no litter-level sensing. Detection differs: the 4 "uses laser and weight sensor technology" (curtain sensors plus weight sensors, manual p. 21); the EVO page names "weight sensors," its manual p. 38 adds "optical sensors." Both pause on added weight mid-cycle, with a 7-minute default delay adjustable to 30. A litter-level readout or the LitterHopper: the 4.

Consumables and compatibility

Monthly parts fit both; add-on hardware mostly does not (litter-robot.com, 10/09/2026).

The holder conflict is Whisker against Whisker: the holder page says "Not compatible with Litter-Robot 3 or EVO," the EVO manual says the holder "snaps right into the Litter-Robot EVO filter cover," and Whisker's OdorTrap installation guide sides with the page: "We do not recommend using the OdorTrap Holder with Litter-Robot EVO" (all three read 10/14/2026). Full list: Litter-Robot accessories.

Warranty and returns

Both include one year of WhiskerCare, covering "Accidental damage, material/workmanship defects, power surges" (legal page). The 3-year plan splits them: $99 for the EVO, $129 for the 4, purchasable within the first year. Returns are a 90-day in-home trial on litter-robot.com orders: you pay return shipping or take the prepaid label with $60 deducted, a "$75 cleaning fee" applies to unclean units, and the refund lands "within 7-10 business days" after receipt. Retail purchases go back through the retailer. Cheapest long-term coverage: the EVO.

What owners complain about

Not enough owner reviews read yet for either: 8 for the EVO (3 App Store, 5 Trustpilot, the latter about the seller) and 43 for the 4 (18 and 17 posts in two thecatsite threads, 3 App Store, 5 Trustpilot). r/litterrobot and Chewy were unreachable on 10/09/2026; we don't count reviews on Whisker's site (EVO 4.7 of 5 over 52; the 4, 4.5 over 14,096).

Litter-Robot 4 sample: customer support 4 mentions, sensor errors 3, app or Wi-Fi 2, cat refusing the box 2. thecatsite, 09/09/2026: "It does have problems with now and then randomly going offline." Praise is about service, Trustpilot, 09/20/2026: "Customer service under extended warranty has been amazing." EVO: one reviewer-level complaint, technomeow.com, 02/25/2026: "If you already have the EVO and are getting a ton of position fault errors, update the firmware." With 8 EVO reviews read, there is no EVO complaint pattern to report yet.

Safety and recalls

No recall found for either: the saferproducts.gov recall API returned nothing for "Whisker," "Litter-Robot," or "litter box" on 10/14/2026, and cpsc.gov/Recalls returned nothing related for the same terms on 10/09/2026. The 4 is "a Class 1 Laser Product in accordance with IEC 60825-1:2014" (manual p. 39) because of its curtain sensors; the EVO relies on weight and, per its manual, optical sensing. Both manuals keep cats under 3 lb (1.36 kg) out of unattended automatic mode.