A litter box for small spaces should be compact — but not cramped. One of the most common mistakes owners make is grabbing the smallest box on the shelf simply because space is tight. If your cat can't turn around, dig properly, or get in and out comfortably, they'll start avoiding it.
The box needs to suit the size of your cat, not just the size of your bathroom. If it's too small, you'll end up with litter scattered around the outside, misses beside the box, or a cat that goes looking for a better spot.
For smaller apartments, corner boxes, high-sided models, covered options, or furniture-integrated solutions where the box sits inside a cabinet can all work well. Just don't sacrifice your cat's comfort for the sake of appearances.