The math
- Total = box price + (consumables + litter) × 12 × years.
- Box price is the lowest typical street price on each review page (dated sources), not a live Amazon price.
- Consumables use each maker's own prices where we could confirm them, at the usage rate the maker suggests. Where a brand's bag price couldn't be confirmed, we use Whisker's $1-per-liner price as a stand-in, which you can change.
- Litter = pounds per cat per month × price per pound × cats. Crystal-tray boxes skip this line because the tray includes the litter.
- Manual box = setup cost + the same litter, plus bags if you tick that box.
Where the consumable prices come from
| Profile | Item | Unit price | Basis |
|---|---|---|---|
| Whisker Litter-Robot | Waste drawer liners | $1.00 | Whisker: 25 liners for $25. Whisker says the drawer may need emptying as rarely as every 8 days; we assume about 4 liners per cat per month. |
| Carbon filter | $5.00 | Whisker: 6 filters for $30, "1 filter = 1 cat", replace every 2–4 weeks; we use one per cat per month. | |
| OdorTrap packs (optional) | $5.00 | Whisker: 6 packs for $30, replace every 2–4 weeks; optional. | |
| Whisker Litter-Robot 5 (Whisker+) | Waste drawer liners | $1.00 | Whisker: 25 liners for $25; about 4 per cat per month (our assumption from Whisker's 8-day figure). |
| Carbon filter | $5.00 | Whisker: 6 for $30, replace every 2–4 weeks. | |
| Whisker+ subscription (optional) | $6.67 | WIRED: about $80 a year; needed for WasteID and reliable cat ID. | |
| PETKIT PuraMax / Purobot | Waste bags | $1.00 (stand-in) | PETKIT's listing suggests changing bags twice a week for two cats (about 4.3 per cat per month). We couldn't confirm PETKIT's bag price, so we use Whisker's $1-per-liner price as a stand-in; third-party 120-packs are usually cheaper. |
| Odor-eliminator refill (optional) | $6.67 | Stand-in: WIRED cites $20 for three of PETKIT's Purobot Ultra odor refills; we couldn't confirm the N50 price. One N50 lasts about a month (Amazon listing). | |
| PETKIT Purobot Ultra | Auto-bag rings | $1.00 (stand-in) | Bag-ring price not confirmed; Whisker's $1-per-liner price used as a stand-in at PETKIT's suggested change rate. |
| Odor-eliminator refill | $6.67 | WIRED: $20 for three refills; about one a month. | |
| PetSafe ScoopFree Crystal | Disposable crystal tray | $24.50 | PetSafe: 3 trays for $73.49 (Nov 12, 2026). PetSafe says one tray lasts about a month for one cat; a Chewy answer gives 10–15 days for two cats. |
| PetSafe ScoopFree SmartSpin | SmartSpin liners | $0.72 | Amazon listing: 25 liners, $17.99 list. PetSafe: the 6 L drawer holds up to two weeks for one cat. |
| Standard drawstring bags | Waste bags | $1.00 (stand-in) | Stand-in: Whisker's $1-per-liner price at about one bag per cat per week. Third-party 120-packs are usually cheaper; enter your own price. |
Litter default: Dr. Elsey's Ultra unscented, 40 lb for $22.99 at Chewy (Nov 2026). The 10 lb per cat per month figure is our planning assumption, not a measurement. Weigh what you actually buy in a month and enter it.
Crystal-tray boxes include litter in the tray price. Change any assumption in the cost calculator.
A worked example
Two cats, five years, default litter. A PETKIT PuraMax 2 starts at about $390. Its bags at the stand-in price come to about $8.60 a month (4.3 bags per cat), and litter for two cats at 10 lb each is about $11.50 a month. Over 60 months that's roughly $1,200 of bags and litter, so about $1,600 all in. A Litter-Robot 4 at $699 adds liners and carbon filters at Whisker's prices (about $18 a month for two cats) plus the same litter, for about $2,470. A ScoopFree Classic costs only about $100 up front, but two trays a month at about $24.50 each come to roughly $2,940 over five years plus the box, more than either. A manual box with the same litter is about $690.
The takeaway: the cheapest box to buy is often not the cheapest to own, and crystal-tray running costs scale fast with more cats. For the bigger picture, read are self-cleaning litter boxes worth it?