Multi-unit sizing
How Many Air Purifiers Do I Need?
Enter the room volume, target air changes per hour and one purifier's CADR. The calculator returns the minimum number of units and the ACH they would deliver together.
What the calculator is doing
Required clean-air flow in CFM = room area × ceiling height × target ACH ÷ 60. The result is divided by the CADR of one purifier and rounded up to a whole unit.
Why multiple units can make sense
One large purifier is not always the best distribution strategy in long, divided or open-plan spaces. Multiple units can place clean-air delivery closer to occupied zones, though closed doors still limit cross-room cleaning.
AHAM recommends tobacco-smoke CADR of at least two-thirds of room area as a simple sizing rule, and notes that higher ceilings call for a larger unit.