Litter-Robot 4 Review 2026 — Is It Worth $699?

With one cat, the waste drawer needs emptying every 7-10 days. With two cats, every 5-7 days. With four cats, every 2-3 days.

Yes — the combination of the carbon filter, sealed waste drawer, and automatic sifting (waste doesn't sit exposed) provides the best odor control we've analyzed in any litter box.

Most clumping clay litters work well — Arm & Hammer Clump & Seal, Dr. Elsey's, and World's Best all sift cleanly. But compatibility is more limited than owners expect, and three problems come up repeatedly: (1) Non-clumping litters fail entirely — the sifting mechanism needs solid clumps to separate waste, so pine, paper pellets, and non-clumping clay don't work. (2) Coarse granules jam the sifting screen — large wood pellets and coarse crystals get trapped and can't pass through. (3) Humid climates undermine odor control — in hot, damp environments the carbon filter saturates faster, so you'll change filters more often. Stick to fine-to-medium clumping litter (clay, corn, walnut, or grass) for reliable performance.

Avoid all non-clumping litter, pine pellets, paper pellets, tofu litter with oversized granules, and coarse crystal litter. These either fail to clump (so waste isn't separated) or are too coarse to pass through the sifting screen (causing jams). Whisker sells its own litter, but any fine-grain clumping clay or natural clumping litter works — you don't need the branded product.