What is the best air purifier for cat litter smell in a small apartment?

Best pick for cat litter smell in a small apartment: Coway Airmega AP-1512HH Mighty. It is a strong all-around choice because it combines true HEPA filtration for dander/dust with an activated-carbon odor filter, has good room coverage for many apartments, and is compact enough for a bedroom or living area near—but not directly beside—the litter box.

If odor control is the top priority, choose Winix 5500-2 instead: its washable carbon filter is a better fit for recurring pet and litter-box odors. If the apartment is very small or you want the simplest budget option, Levoit Core 300S is easier to place, but its odor control depends heavily on using the pet/odor-focused replacement filter.

Important: no air purifier will fully solve litter smell if the source is strong. For best results, scoop daily, use low-dust clumping litter, keep the purifier a few feet from the litter box with clear airflow, and replace carbon filters on schedule.