Litter Boxes for Large Cats: How Big Is Big Enough?

A litter box for a large cat should be about 1.5 times the cat’s length from nose to base of tail, according to veterinary guidance from the Feline Veterinary Medical Association and International Cat Care. For a 20-inch Maine Coon, that means a box around 30 inches long.

“In general, bigger is better and many commercial litter boxes are too small,” says the Feline Veterinary Medical Association (FelineVMA, the new name of the American Association of Feline Practitioners) in its client guide on house soiling. The same guidance goes back to the 2014 AAFP and ISFM house-soiling guidelines, which name the litter box as one of two first steps in any house-soiling problem.

How to measure your cat for a litter box

Measure from the tip of the nose to the base of the tail, not to the tail tip. A relaxed cat lying on its side is easiest. Then multiply by 1.5:

These are worked examples, our arithmetic: each row multiplies an example length by the 1.5 factor from FelineVMA and International Cat Care, and the result is an estimate of the minimum. FelineVMA notes that many commercial boxes are too small, so check the inside length in the listing, not the outside size. Width matters too: a big cat needs room to turn around and dig.

Storage bins and mixing trays

FelineVMA names “concrete mixing trays or storage containers” as suitable alternatives. They are often the easiest way to get a 30-inch box. Two adjustments make a bin work:

• Cut a low entry on one side if the cat is older or stiff. FelineVMA says older cats “need a low entry,” and to check for sharp edges.
• Keep the lid off, or place it behind the box to protect the wall, as FelineVMA suggests.

Extra large and high-sided litter boxes

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Open, covered or top entry?

Open boxes are the safe default. Cornell Feline Health Center says “most cats prefer simple boxes without hoods,” and the AAFP’s Claw Friendly toolkit recommends uncovered boxes. International Cat Care adds a point that matters for big cats: “Large breed cats in particular may find smaller hooded trays challenging to use,” because they cannot position themselves or dig easily.

Top-entry boxes ask the cat to jump in and out through the lid. For a young, agile cat that may be fine. For a heavy or older cat, or one with stiff hips, a low-sided open box is kinder; see heart and hip health in large breeds.

How many boxes, and where?

FelineVMA’s rule is “one litter box for each cat, plus one extra box, in multiple locations around your home.” Boxes placed side by side do not count, because the cat “considers boxes close to each other one large litter box.” Other placement advice from the same guide:

• Quiet, private spots, away from food and water.
• Not in busy corridors or corners where another pet can block the way out.
• One on each level of a multi-level home, and for an older cat, one where it spends most of its time.

Litter, depth and cleaning

FelineVMA says “most cats prefer soft, unscented, clumping litters” and that many dislike scented litter, deodorizers and liners. International Cat Care cites research showing cats prefer a litter depth of about 3 cm, a little over an inch.

On cleaning, FelineVMA says to remove waste at least once a day and wash the box every one to four weeks with soap and hot water only. International Cat Care goes further and suggests scooping at least twice a day. A big cat produces more waste, so a bigger box also needs more litter and more frequent topping up.

What about self-cleaning boxes?

Automatic boxes save scooping, but fit is the question for a big cat: each maker states its own weight range and entry size, and International Cat Care notes that many are small and that their movement can startle cats. See self-cleaning litter boxes for large cats for the makers’ stated limits. For the rest of the gear a big cat outgrows, start at the supplies hub.