What CADR Does Your Room Actually Need?
What CADR does your room actually need?
Most coverage claims on the box are calculated at 1–2 air changes per hour. For allergy control, you need 5. Here's the math.
CADR: Clean Air Delivery Rate. It is how much filtered air a purifier produces per hour, measured in cubic metres (m³/h) or cubic feet per minute (CFM).
But CADR alone doesn't tell you whether a purifier is right for your room. The number that actually matters is ACH: Air Changes per Hour: how many times per hour the purifier processes all the air in your space. For meaningful allergy control, that minimum is 5 ACH.
Adjust your room dimensions and target ACH below. The required CADR updates in real time.
What CADR do you actually need?
For this space, you need a purifier with a CADR of approximately:
575 m³/hFor reference: many purifiers marketed for "large rooms" deliver 200–300 m³/h. A CADR of 380–420 m³/h comfortably covers a typical 40–50 m² Canadian living area at 5 ACH.
If a brand quotes coverage area without saying at how many ACH it was calculated, assume the number is low and the purifier will be perpetually behind on a real day in a real home.
We make a HEPA H13 purifier designed for Canadian homes
True H13 filtration, published CADR at 5 ACH, ozone-free ioniser, replacement filters, sub-30 dB Sleep Mode.