Air Purifier Coverage
Find the room size an air purifier can serve at the right air changes.
About Air Purifier Coverage
A purifier needs a clean-air delivery rate equal to the room volume times the desired air changes per hour. Comparing that to the CADR rating checks adequacy. An undersized purifier cleans too slowly to help with allergens or smoke, so matching CADR to room size is essential.
Formula
Air Purifier Coverage
Required CADR = room volume x air changes / 60
- ACH
- Air changes per hour, a measure of cleaning speed
Worked example
With the default values below, Air Purifier Coverage returns Room Volume of 2,000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Room areaminimum 0 sq ft
- 250 sq ft
- Ceiling heightminimum 0 ft
- 8 ft
- Air changes/hourminimum 0.1 ACH
- 4 ACH
- Purifier CADRminimum 0 cfm
- 300 cfm
Results
- Room Volume
- 2,000 cu ft
- Required CADR
- 133.3 cfm
- Area This CADR Covers
- 563 sq ft
- Is It Adequate?
- Adequate for this room
Step by step
- 1Values used
- 2Air Purifier Coverage
- 3Room Volume= 2,000 cu ft
- 4Required CADR= 133.3 cfm
- 5Area This CADR Covers= 563 sq ft
- 6Is It Adequate?= Adequate for this room
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Air Purifier Coverage calculated?
Required CADR = room volume x air changes / 60 A purifier needs a clean-air delivery rate equal to the room volume times the desired air changes per hour. Comparing that to the CADR rating checks adequacy.
Why does Air Purifier Coverage matter?
An undersized purifier cleans too slowly to help with allergens or smoke, so matching CADR to room size is essential.
What values do I need to enter?
This calculator takes 4 inputs: Room area, Ceiling height, Air changes/hour, Purifier CADR. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.