Litter & Litter Tech
Litter-Robot 4 vs PetSafe ScoopFree
The sticker prices are miles apart and they are the wrong number to start with. What separates these two is the consumable, and it runs the other way.
Affiliate disclosure: we earn a commission if you buy through our links, at no extra cost to you. It never changes which product we rank first — here is how we're funded.
Everyone in this category says they tested twenty litter boxes. We have not tested any, and we say so. What we do instead: compile the published specs, read the manuals, and do the arithmetic on what this gear costs to run and how it behaves once there is more than one cat using it. Every spec is linked to the document it came from. Prices are checked daily — last verified September 25, 2026. Here is exactly how we pick.
One of these costs several times what the other does. Look only at that and you will buy the wrong one, because the cheaper machine is the one with a subscription attached.
Two different machines
The Litter-Robot 4 is a sealed globe that rotates after a visit, sifting clumps through a screen into a drawer below. It runs on ordinary clumping litter, which you top up.
The ScoopFree Crystal Smart is a flat tray with a rake that sweeps waste into a covered compartment at one end. It runs on PetSafe crystal litter, supplied in pre-filled disposable trays that you throw away whole.
Everything below follows from that difference. Our automatic box roundup ranks the whole field, and our Litter-Robot 4 against 5 page covers the in-family upgrade.
What each one publishes
| Specification | Litter-Robot 4 | ScoopFree Crystal Smart |
|---|---|---|
| Mechanism | Rotating globe, sifted into a drawer | Raking tray, waste swept to one end |
| Litter | Any clumping litter | ScoopFree crystal litter only |
| Footprint / height | 22" W x 27" D x 29.5" H | 27.6" x 19.1" x 6.2" uncovered; 15.6" H front-entry |
| Entry | 15.75" x 15.75" opening | Open tray, or a front-entry hood |
| Cat weight range | 3 to 25 lb | Not published |
| Consumable | Ordinary clumping litter | Disposable trays; up to one month for one cat |
| Multi-cat guidance | No published cat-count rating | PetSafe: "your mileage may vary" |
| Power | 15 V DC, 400-1000 mA (6-15 W) | Plug-in; wattage not published |
| Empty weight | 24 lb | Not published |
| Warranty | 1 year; 3-year plan optional | See PetSafe |
Manufacturers' published figures. Blank cells are blanks in the maker's own specification, not gaps in our research.
The consumable is the product
ScoopFree trays. PetSafe publishes a tray life of up to one month for a single cat, and lists trays at $73.49 for a three-pack. Twelve trays a year is four packs: about $294 -- more, for one cat, than the machine itself costs at the price we have seen it sell for.
Litter-Robot 4 electricity. Whisker publishes a 6 to 15 W supply. Running at the 15 W ceiling all year at the EIA residential average of 18.34 cents per kWh is $24.10, and the real figure is lower because the motor only runs in bursts.
The Litter-Robot still needs litter, and that is a genuine cost -- but it is ordinary clumping litter bought at whatever price you like, in a category where our litter comparisons show real choice. The ScoopFree tray has exactly one supplier.
Both buttons on this page show today’s live price where we have verified one within 48 hours, which is the only price we will quote for the machines themselves. The tray arithmetic above uses PetSafe’s published list price, and the loose crystal refills are the cheaper way to feed a ScoopFree if you are willing to fill a tray yourself -- PetSafe publishes 8 lb lasting up to two months for one cat.
What each asks of the cat
The Litter-Robot 4 asks a cat to step up and walk into an enclosed globe through a 15.75 inch square opening. Most cats accept it; some never do. The Ohio State Indoor Pet Initiative reports that cats generally prefer large, uncovered boxes, which is a point against any enclosed design.
The ScoopFree is closer to that preference in its uncovered form: a flat open tray 6.2 inches tall, with a front-entry hood available if you want containment instead. It is also the lower machine by a long way, which matters under a shelf.
The specification the ScoopFree does not publish is a cat weight range. Whisker publishes 3 to 25 lb for the Litter-Robot 4. For a large cat, that blank is the whole argument -- our large-cat automatic page ranks the category on exactly this.
With more than one cat
Neither maker publishes a cat-count rating for these two models. What PetSafe does say is that the one-month tray life applies to a single cat and that beyond that your mileage may vary, which is honest and also the end of the cost argument: two cats means roughly twice the trays, and the $294 doubles with them.
- One cat: the ScoopFree is viable, and cheapest on day one.
- Two cats: the tray cost roughly doubles while the Litter-Robot’s electricity does not move.
- Three or more: one automatic box of either kind recreates the queue it was bought to remove. Our box count page and multi-cat automatic page both land on the same answer: buy boxes before you buy machines.
Which to buy
- Lowest price today, one cat, short horizon: the ScoopFree. It is the cheaper machine and it works.
- Keeping it for years: the Litter-Robot 4. The purchase gap closes as trays accumulate; our running costs page shows the crossover.
- A large cat: the Litter-Robot 4, on the published weight range the ScoopFree lacks.
- A cat that refuses enclosed boxes: the ScoopFree uncovered, or an open-top automatic box -- our Litter-Robot against Neakasa M1 page covers that design.
- Not sure an automatic box is worth it at all: our worth-it page does that arithmetic before any of this matters.
The gear discussed here
Specs are the manufacturer's own, linked to the page they came from. Prices come from a live daily check; where we have no verified price we say so rather than print a stale one.
Whisker Litter-Robot 4
Whisker · Automatic litter box · Our score 8.1/10
Reference link This one sells direct and we earn nothing on it. We link it anyway because it belongs in the comparison. How we're funded.
The biggest entryway and the largest published cat-weight range of the enclosed units, and the only one whose maker publishes an actual power-supply spec you can cost out.
Published specs
| Entryway | 15.75" x 15.75" |
|---|---|
| Footprint / height | 22" W x 27" D x 29.5" H |
| Weight, empty | 24 lb |
| Cat weight range | 3-25 lb |
| Power supply | 15 V DC, 400-1000 mA (6-15 W) |
| Warranty | 1 year, 3-year plan optional |
| Globe / drawer capacity | Not published by Whisker |
Source: Whisker -- Litter-Robot 4 product page and power supply spec article
Whisker's own spec sheet accepts a 15 V supply between 0.4 A and 1.0 A. Take the 1.0 A ceiling: 15 W x 24 h x 365 = 131.4 kWh, x $0.1834 = $24.10. That assumes the motor runs flat out every hour of the year, which it does not -- so the real figure is well below this. The consumables are the actual cost.
What the specs favor
- Largest published entryway of the enclosed units here, at 15.75 inches square
- Whisker publishes a real power-supply rating, so running cost is computable
- Cat weight range published as 3-25 lb
- Three-year extended warranty available at purchase
What they don't
- Whisker does not publish globe or waste-drawer capacity, which is the number that actually decides how often you empty it with three cats
- Waste drawer liners are a proprietary consumable at $25 per 25-pack
- Carbon filter is a separate monthly consumable
- Sells mainly direct, so there is no reliable Amazon price to track
You have five cats. Whisker rates the newer Litter-Robot 5 for up to five and this one carries no published cat-count rating at all -- buying the older unit for a bigger household is guessing.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
PetSafe ScoopFree Crystal Smart
PetSafe · Automatic litter box · Our score 6.2/10
#ad Price as of September 25, 2026. Prices move; we check daily. How we're funded.
The cheapest automatic box here at $269.99 and by a wide margin the most expensive to run, because the disposable tray is the entire consumable model.
Published specs
| Dimensions, uncovered | 27.6" x 19.1" x 6.2" |
|---|---|
| Dimensions, front-entry | 27.6" x 19.1" x 15.6" |
| Litter | ScoopFree crystal litter only |
| Tray life | Up to one month for a single cat (PetSafe) |
| Tray price | $73.49 per 3-pack (PetSafe list) |
| Power | Plug-in; wattage not published |
| Multi-cat guidance | PetSafe: "your mileage may vary" |
Source: PetSafe -- ScoopFree Crystal Smart product page and tray 3-pack listing
PetSafe lists the 3-pack at $73.49, so $24.50 a tray, and says one tray covers one cat for up to a month. Twelve trays a year is $294 -- more than the $269.99 box. With three cats the tray fills three times as fast, which is roughly $880 a year on the same arithmetic.
What the specs favor
- Lowest purchase price of the automatic boxes here
- Largest floor area of the automatic boxes at 27.6 x 19.1 inches
- Available uncovered, which is the shape cats prefer
- No scooping and no litter handling at all
What they don't
- Locked to PetSafe's own crystal litter -- no substitution
- Disposable trays cost more per year than the box costs to buy
- PetSafe publishes no wattage, so electricity cannot be computed
- PetSafe declines to give multi-cat guidance beyond 'mileage may vary'
You have more than one cat. The tray is the product, and with three cats the tray arithmetic runs to roughly $880 a year -- three or four times what a clumping-litter automatic box costs to feed.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
PetSafe ScoopFree Premium Crystal Litter
PetSafe · Crystal litter · Our score 7.6/10
#ad Price as of September 25, 2026. Prices move; we check daily. How we're funded.
The only substrate here whose maker publishes a direct weight-for-weight replacement ratio against clay, and it is 5 to 1.
Published specs
| Material | Silica gel crystals |
|---|---|
| Bag sizes | 4.3 lb, 8 lb, 10 lb |
| Published duration | 8 lb lasts up to 2 months for one cat |
| Replacement ratio | 8 lb replaces 40 lb of traditional clay clumping litter |
| Dust | 99 percent dust-free |
| Mechanism | Absorbs urine, dries solid waste |
| Clumping | No |
PetSafe publishes that an 8 lb bag replaces 40 lb of traditional clay clumping litter. That is a 5 to 1 weight ratio for the same duration, and it is the clearest published argument for crystal: the difference is 32 lb you do not carry from a car to a flat every two months.
What the specs favor
- Publishes an explicit replacement ratio against clay, which no other substrate here does
- 99 percent dust-free on the maker's own figure
- Very light to carry for the coverage it gives
- Solid waste dries rather than sitting wet
What they don't
- Does not clump, so urine is absorbed into the bed rather than lifted out
- Crystals are sharp underfoot and some cats refuse them outright
- Not flushable and not biodegradable
- The published duration figure is for one cat only
You have more than one cat and want to scoop urine out. Crystal absorbs rather than clumps, so multi-cat volume saturates the bed on a schedule you cannot see.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Common questions
Which is cheaper, the Litter-Robot 4 or the ScoopFree?
Can you use normal cat litter in a ScoopFree?
Is the Litter-Robot 4 worth three times the price?
Which one is better for multiple cats?
Which suits a large cat?
Sources
- Whisker -- Litter-Robot 4 product page and power supply spec article
- PetSafe -- ScoopFree Crystal Smart product page and tray 3-pack listing
- PetSafe -- ScoopFree Premium Crystal Litter product page (8 lb bag, up to 2 months for one cat, 99 percent dust-free, replaces 40 lb of clay)
- Ohio State University Indoor Pet Initiative -- Litter Boxes
Read next
- Best Automatic Litter Boxes (2026)
The head-term roundup, ranked on published capacity and consumable model rather than app features.
- What an Automatic Litter Box Actually Costs to Run
The full year-one and year-two running cost of every major automatic litter box, computed from published prices with the arithmetic shown.
- Litter-Robot 4 vs Litter-Robot 5
The $100 difference explained from Whisker's own spec sheets, with a clear verdict by household size.
- Are Automatic Litter Boxes Worth It?
Break-even arithmetic against ordinary boxes, worked from published prices, with a clear answer for one, two and three cat households.
- Best Budget Automatic Litter Boxes (2026)
Three-year cost of ownership computed from published prices -- which reverses the sticker-price ranking entirely.