Appliances & Utilities calculator
What Air Purifier Size Do I Need?
Use room length, room width, room height to find minimum cadr.
Enter your measurements
What Air Purifier Size Do I Need uses room length, room width, room height and the other configured measurements to return minimum cadr with a formula written specifically for this tool.
- Room length — Required
- Room width — Required
- Room height — Required
- Target clean air changes/hour — Required
Minimum CADR
Enter the measurements above to calculate minimum cadr.
How the calculation works
V17 calculation: roomVolume=roomLength×roomWidth×roomHeight; requiredCADR=roomVolume×targetAirChanges/3600. The result is reported as Minimum CADR.
Worked example
Example: Room length = 450 cm; Room width = 360 cm; Room height = 240 cm; Target clean air changes/hour = 6. Result: Required CADR = 64.8 L/s; Room Volume = 38880 L.
Before you decide
The result is only as accurate as the measurements entered. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what air purifier size do i need, the limiting result on this page is minimum cadr.
Direct measurement/geometry calculation. No external reference is required for the arithmetic itself; the result is derived only from the user-entered measurements and the formula stored in calculationLogicJson.
Frequently asked questions
What does the Air Purifier Size calculator tell me?
It returns minimum cadr from the measurements entered on this page. The calculation is specific to air purifier size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for air purifier size?
Measure room length, room width, room height, target clean air changes/hour. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the minimum cadr?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned minimum cadr while allowing for the clearances, tolerances or ratings shown by its manufacturer.