Air Purifier CADR Estimator
This estimator converts room volume and a selected clean-air changes-per-hour target into a clean-air delivery rate. It can help compare product specifications without replacing indoor-air advice.
How to use this calculator
- Use a CADR specification stated for the pollutant and operating mode you care about.
- Check that the input values use the same units and reporting period before comparing scenarios.
- Change one assumption at a time to see which input drives the result.
Formula and method
Required CADR (m³/h) = room floor area × ceiling height × target air changes per hour.
- Room volume = 78 m³; required clean-air delivery = 78 × 5 = 390 m³/h.
- Room conditions, pollutant type, filter performance, noise settings, doors, ventilation and manufacturer test methods affect performance. This is not a medical assessment or a guarantee of contaminant removal.
Worked examples
Worked example
A 30 m² room with a 2.6 m ceiling and a target of 5 changes per hour.
Room volume = 78 m³; required clean-air delivery = 78 × 5 = 390 m³/h.
The target corresponds to a CADR of about 390 m³/h.
Understanding the result
The target corresponds to a CADR of about 390 m³/h.
Room conditions, pollutant type, filter performance, noise settings, doors, ventilation and manufacturer test methods affect performance. This is not a medical assessment or a guarantee of contaminant removal.
Important notes
Use a CADR specification stated for the pollutant and operating mode you care about.
The displayed result uses the entered assumptions; validate important estimates against source measurements, specifications or qualified guidance.
Frequently asked questions
Does the number of air changes prove air quality?
No. It is a flow-volume estimate and does not measure pollutants or real-room mixing.
Can I combine multiple units?
A simple sum is an approximation; placement, mixing and manufacturer specifications still matter.
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Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.