As an Amazon Associate I earn from qualifying purchases. Links to Amazon on this page are affiliate links.

That air purifier will not clean 1,500 square feet

Most boxes quote the area a purifier can filter once per hour. Allergy and smoke guidance is built on about five air changes per hour. Divide the number on the box by 4.8 and you get the room it can really keep clean.

Check any purifier in 10 seconds

Guides

• The 5 best air purifiers, matched to real room size

  Air purifiers matched to the room they can really clean at 4.8 air changes per hour: small bedroom, bedroom, living room, large room.

• What room will it really clean?

  Enter the coverage claim or CADR from any air purifier and get the room size it can clean at 4.8 air changes per hour.

• Why the room size on the box is about five times too big

  What 'covers 1,500 sq ft' really means, how CADR works, and the two-thirds rule for sizing an air purifier.

• What it really takes to run an air purifier every day

  What it takes to run an air purifier all day: filter schedules, electricity math and noise tradeoffs.