CADR explained
Clean Air Delivery Rate is the volume of filtered air a purifier delivers per minute, in cubic feet per minute. It is measured in a sealed test chamber by the Association of Home Appliance Manufacturers (AHAM) under ANSI/AHAM AC-1, with three separate figures for smoke, dust and pollen.
Why we rank on smoke CADR
Smoke particles are the smallest of the three, roughly 0.1 to 1 micron, which is also the range of wildfire smoke, cooking fumes and most of what makes indoor air unhealthy. Dust and pollen are larger and easier to catch, so their CADR figures are almost always higher. A unit with a strong smoke CADR will handle the other two.
Sizing a room
AHAM's rule of thumb: smoke CADR should be at least two-thirds of the room's floor area in square feet, assuming an 8-foot ceiling. That gives roughly 4.8 air changes per hour, enough for allergy and smoke relief.
- 150 sq ft bedroom → about 100 CADR
- 300 sq ft living room → about 200 CADR
- 500 sq ft open area → about 330 CADR
Manufacturers often quote a much larger room size based on one air change per hour. That is the number on the box; the AHAM number is the one we show on every page.
Certified vs claimed
An AHAM Verifide listing means an independent lab measured the CADR. A manufacturer-claimed CADR is self-reported. Both appear in our catalog, but certified units score higher on the certification component of our formula, and the model page says which kind of figure it has.
What CADR does not tell you
CADR says nothing about gases and odors, which need activated carbon. It also says nothing about noise, which is why we show rated sound levels and rank quieter units higher within each room-size class.