This Harvard Healthy Buildings Portable Air Cleaner Sizing tool (PACS) was developed by the Harvard Healthy Buildings program to help people select an appropriately-sized portable air cleaner for indoor spaces. Users input their “clean air” target (measured in units of equivalent air changes per hour, or ACHe) and information about the size of the room. The calculator returns the “clean air delivery rate” (CADR) the user should look for from the air cleaner manufacturer. The tool can also be used in the reverse. The user inputs the CADR on a portable air cleaner they have or are considering, and the calculator returns the room size.
Limitations: Portable air cleaning is only one of several methods for reducing the concentration of airborne particles indoors, including those from the respiratory tract that may contain infectious viruses or bacteria or those from outdoor or indoor pollution. For more information on portable air cleaners, please review our report on PACs for infectious disease reduction or our wildfire advisory.
Determine the air cleaner(s) required in a room to reach a target equivalent air exchange rate (eACH).
Find the largest room acceptable for a given clean air delivery rate (CADR), to reach a target equivalent air exchange rate (eACH).
Target equivalent air exchanges per hour
 |
Ideal (6 ACH) |  |
Excellent (5-6 ACH) |  |
Good (4-5 ACH) |  |
Minimum (3-4 ACH) |  |
Low (< 3 ACH) |
|
Ideal (6 ACH) | |
Excellent (5-6 ACH) | |
Good (4-5 ACH) |
|
Minimum (3-4 ACH) | |
Low (< 3 ACH) |
Configure the settings and then click the button below to calculate.
Calculating...
| Total Target CADR: | 0 |
| CADR from Room Ventilation: | 0 |
To meet the target eACH:
The ventilation of the room is 1 ACH higher than the target eACH level without any additional air cleaners.
The height of this room may not be appropriate for human habitation.
