The best smart air purifiers of 2025: Expert tested and reviewed

An important consideration for air purifiers is filter replacement. Some models require regular replacements of expensive filters, which could cost hundreds of dollars per year. 

Before you purchase a model, look into what type of replacement filters you’ll need, how much they cost, and whether you can afford to replace them as required. Otherwise, choosing not to replace filters as recommended could reduce the air purifier’s efficiency. After all, they capture and trap harmful particles, such as mold spores and bacteria. 

Some air purifiers feature washable filters, which make maintenance easier. However, the most effective air purifiers include HEPA filtration and carbon filters, which must be replaced. The manufacturer’s requirements are in the manual.

Some modern purifiers have an indicator light that warns you when to replace the filters. As a rule of thumb, plan on replacing carbon air filters every three months and other filters every six months.