What size litter box does my cat need?

Working out the size

Measure the cat nose to tail base, excluding the tail, then multiply by one and a half. A 16-inch cat wants roughly 24 inches of internal length. The cat needs room to turn around, dig before, and cover after, all without touching the sides.

• Length is the number that matters. Width and depth follow from a sensibly proportioned box.
• Sides around six inches high contain digging without becoming a climb.
• For kittens, seniors and arthritic cats, one low entry point matters more than overall height. A cut-down section on one side solves this.
• Large breeds such as Maine Coons and Norwegian Forest Cats routinely exceed every box sold as extra-large.

Why a storage tub is often better

A plain under-bed storage container gives more internal length than most purpose-made boxes, costs less, and has higher sides for enthusiastic diggers. Cut a low entry into one end with a hacksaw and sand the edge smooth. This is the single most effective cheap fix for a cat who has started going just outside the box.

How much litter to put in

• Two to three inches for clumping litter. Deeper wastes litter and does not improve anything; shallower means clumps stick to the base.
• Keep the depth consistent, since cats notice the change and some object to it.
• Top up after scooping rather than waiting for a full change, so the level does not drift down over a week.
• Unscented is the safer default. Fragrance is added for the owner and is a common reason a cat quietly stops using a box.