Filter cost explained
A purifier that costs $150 with a $50 filter rated for six months costs $100 a year in filters. Over five years that is $500, more than three times the sticker price. Two units with the same CADR and the same price can differ by hundreds of dollars in total cost.
How we calculate it
- Annual filter cost = replacement price × 12 ÷ rated filter life in months, using the manufacturer's own filter and life rating.
- Filter cost per 100 CADR normalizes that figure so a 400-CADR unit isn't penalized for needing a bigger filter than a 130-CADR unit.
- Five-year cost of ownership = purchase price + 5 × annual filter cost. We show it on every model page.
Power is not included in the ownership figure because it depends on your electricity rate and how many hours you run the unit. We score it separately as CADR per watt.
What shortens filter life
Rated life assumes typical indoor air. Pets, cooking, smoking or wildfire season will clog a filter faster. A washable prefilter catches hair and lint before they reach the HEPA layer and can stretch its life, which is why we give it a feature point.
Filters you can't replace
Some units sell on a "no filter change" promise. The math only works if the filter genuinely lasts; we record the manufacturer's rated life and let the cost formula speak.
See the cheapest purifiers to run.