Key takeaways
- Match the clean air delivery rate (CADR) to your room: EPA's table works out to about two-thirds of the room's square footage.
- Avoid ozone generators; no federal agency has approved them for occupied spaces.
- ENERGY STAR certification means lower running costs, not better cleaning.
Size it with CADR
CADR, the clean air delivery rate, is the figure designed to help you match a portable air cleaner to a room. A higher CADR moves more filtered air. The EPA publishes minimum CADR values for particles by room size.[1]
| Room area (sq ft) | Minimum CADR (cfm) |
|---|---|
| 100 | 65 |
| 200 | 130 |
| 300 | 195 |
| 400 | 260 |
| 500 | 325 |
| 600 | 390 |
Filters and what to skip
Portable units often reach high CADRs by using HEPA filters. Filters need to be replaced on schedule to keep performing, so check the cost and availability of replacements before you buy.[1]
If your home has central heating and air conditioning, the EPA suggests using a MERV 13 filter, or the highest rating your system can handle.[1]
What the ENERGY STAR label means here
ENERGY STAR measures efficiency, not cleaning power. Certified room air cleaners are more than 50% more energy-efficient than standard models, which the program estimates can save about $18 to $40 a year depending on size. Certified models must also keep measured ozone at or below 50 parts per billion.[2,3]
Air purifier checklist
- CADR at least about 2/3 of the room's square feet
- HEPA filter, with affordable replacements
- No intentional ozone generation
- ENERGY STAR certified for lower running costs
- Quiet enough at the speed you'll actually use
Sources
Every figure in this guide comes from the official sources below. We summarize them in our own words; check the source for the full guidance.
- 1Guide to Air Cleaners in the HomeU.S. Environmental Protection Agency
- 2Air CleanersENERGY STAR (U.S. EPA)
- 3Room Air Cleaners: Key Product CriteriaENERGY STAR (U.S. EPA)
This guide is general consumer information, not medical, legal or professional advice. Always follow the manufacturer’s instructions for your product. See our editorial policy and affiliate disclosure.
