Walk into any pet shop and you'll find litter boxes in essentially one size: small. The boxes sold as "standard" are designed to fit neatly in a cupboard corner, not to accommodate a cat's actual body. This disconnect between what cats need and what's sold is one of the most overlooked daily discomforts in cat ownership.
The One-Size Rule
The minimum size rule is straightforward: the litter box should be at least one and a half times the length of your cat, from nose to base of tail. For an average adult cat of 46cm (18 inches), that means a box at least 69cm (27 inches) long. Most standard litter boxes sold in shops are around 50cm. They're simply too small.
Go bigger. A storage box from a hardware store, a concrete mixing tray, or a large under-bed storage container all make better litter boxes than anything marketed specifically as a litter box. The extra space lets your cat turn around freely, dig without kicking litter out, and position themselves comfortably — all things they can't do properly in a cramped box.
What Happens When the Box Is Too Small
A too-small box creates specific, recognisable problems. Cats may stand with their rear ends hanging over the edge, depositing waste directly on the floor. Digging becomes exaggerated and messy because there's nowhere to move. Some cats stop covering their waste entirely — not out of defiance, but because there's simply no room to scratch effectively.
Over time, chronic discomfort in the litter box contributes to avoidance behaviours. If your cat has started going beside the box rather than inside it, and medical causes have been ruled out, the box itself is often the reason.
Depth Matters as Much as Length
Litter depth is frequently discussed, but box depth — how tall the sides are — matters equally. High-sided boxes reduce kicking litter out onto the floor, which is one of the biggest tracking complaints owners have. But high sides can make it hard for older cats or those with joint issues to climb in. The solution isn't a low box — it's a covered entry cutout or a box with at least one low entry side.
For senior cats, look for a box where the entry threshold is no more than 10cm off the ground. For kittens and small cats, the same applies. A box that's easy to enter but has high sides elsewhere gives you the best of both worlds.
Does Shape Matter?
Rectangular boxes outperform hooded dome-style boxes in one key area: usable interior space. The curved interior of a dome reduces the actual floor area without reducing the external footprint. A simple rectangular open tray gives your cat the most usable space for the same amount of floor space. Check price on Chewy →
How Many Boxes Does Size Affect?
In a multi-cat household, the size rule applies to every box. But oversized boxes also serve another function: they reduce competition. A confident cat will use the largest box available. That leaves smaller boxes for more anxious cats who may feel threatened in tight spaces. Sizing up is a low-effort way to reduce tension between cats without changing anything else in the environment.
Budget options work perfectly well. A 80-litre Sterilite storage box costs a fraction of a branded litter pan and gives most adult cats all the room they need. Cut a low entry hole in one side, and you've built a better litter box than anything in the pet shop for under ten euros.
The Bottom Line
Your cat's litter box is probably too small. That's not an insult to you — it's the fault of an industry that prioritises shelf space over feline anatomy. Measure your cat, double that length, and buy a box that size or larger. The difference in your cat's comfort — and in how cleanly the box is maintained — is noticeable within days. View on Amazon →