AIR QUALITY · BUYING GUIDE
How to compare air purifiers
Match the purifier to the room, then compare the airflow, noise and filter costs behind the headline claims.
The short answer
Compare clean-air delivery and room coverage on the same basis. Then check noise at a useful fan setting and the exact replacement filter you will need.
Compare air purifiersFive checks before you choose
| Compare | Look for | Avoid assuming |
|---|---|---|
| Clean-air delivery | CADR in cfm or m³/h, with the pollutant identified. | Smoke, dust and pollen scores are identical. |
| Room coverage | Area, ceiling height and air-change rate together. | Every square-foot claim uses the same test basis. |
| Noise | Fan setting and measurement conditions. | The lowest noise figure accompanies maximum airflow. |
| Replacement filters | Exact model compatibility, pack size and replacement guidance. | A filter price is an annual running cost. |
| Practical fit | Dimensions, placement instructions and controls you need. | An app or sensor solves a room-size mismatch. |
See AHAM's explanation of CADR and the EPA's consumer guide.
Room coverage needs an air-change rate
AHAM Verifide's suggested room size is based on 4.8 air changes per hour. A coverage claim at one air change per hour describes a much slower cleaning rate. Compare like with like. A recirculating purifier filters indoor air; it does not provide fresh outdoor air. Source: AHAM air-change guidance.
One purifier, two room-size numbers
Levoit lists the Core 300S-P for 1,051 ft² at 1 ACH or 219 ft² at 4.8 ACH. The product has not changed; the coverage assumption has. Its published CADR is 141 cfm. Source: Levoit product specifications.
AHAM's general rule of thumb is a smoke CADR of at least two-thirds of room area in square feet, with a larger unit needed above an eight-foot ceiling. Its wildfire-smoke recommendation is higher. Check its guidance for your use case. Read AHAM's sizing guidance.
Pair noise with the setting you will use
EPA notes that lower fan speeds filter less air. A quiet sleep setting may be appealing, but you also need enough cleaning performance at that setting. Compare published noise ranges or tests performed under matching conditions. Source: EPA guidance.
For example, Levoit lists a 22–50 dB range for the Core 300S-P. The lower number alone is not evidence that it delivers its headline CADR at 22 dB. Source: Levoit specifications.
Price the replacement filter, not just the machine
Record the exact filter SKU, pack quantity, dated price and manufacturer's replacement guidance. EPA notes that overloaded filters work poorly and need replacement. Source: EPA filter guidance.
These are example inputs, not a quote or a replacement recommendation. Actual intervals depend on the product and use. Electricity is additional.
Before buying, check whether the filter is readily available and whether the quoted price covers a single filter or a multipack. Keep any unverified recurring cost marked as unknown.
Keep the product's limits in view
A purifier supplements pollutant-source control and ventilation. It cannot remove every pollutant. CADR measures particle removal, not gas removal; an odor claim needs separate evidence. Read the EPA's explanation of filtration limits.
The Home Briefing compares published specifications. We do not present these comparisons as hands-on laboratory tests or evidence of a medical benefit.