Fondsites Tools
Clean Air Society
Air Purifier Sizing Calculator
Turn room dimensions and target air changes into a practical CADR estimate.
This calculator helps you size a portable air cleaner for one room or zone. It favors conservative room math over broad marketing claims.
Use the result as a starting point, then consider noise, filter cost, placement, and whether the purifier will actually run long enough.
Interactive Tool
Air Purifier Sizing Calculator
Change the inputs and the result updates in your browser. Results are not saved, shared, or added to the URL.
Result
Adjust the fields to calculate a result.
How to use this tool
- Enter the room length, width, and ceiling height.
- Choose the target use case: everyday dust and pollen, smoke day, bedroom overnight, or large open area.
- Compare the recommended CADR with the purifier’s smoke CADR or particle CADR.
What the result means
CADR is a particle-cleaning airflow estimate. It does not mean a purifier removes every pollutant or solves moisture, carbon monoxide, radon, or source problems.
Higher fan speeds usually clean more air but make more noise. A quieter unit that runs continuously can be more useful than a loud unit that stays off.
Assumptions and limitations
CADR is treated as cubic feet per minute and the room is treated as a simple volume.
Open floor plans, high ceilings, blocked airflow, and strong sources may need more CADR or multiple units.