CADR, filters and room size: choosing an air purifier
What to compare in an air purifier’s documentation, and why room size alone is not enough.
What to check in the documentation
Look for verified CADR, the measurement method, recommended area and operating mode. An area figure without ceiling height and air change rate does not give the full picture.
Room area and air changes
For an initial comparison, use area = CADR / (ceiling height × air changes per hour). The appropriate air change rate depends on the task and conditions; this is not medical advice.
Replacement filters
Before buying, check replacement part numbers, prices and availability. Replacement intervals depend on the instructions and usage. The word HEPA alone does not verify the performance of the whole system.
Everyday comfort
Check noise in the mode you will use, display brightness, placement and ease of maintenance. Leave the clearance around air intakes specified in the instructions.