Room Air Cleaner CADR Calculator
Compare an air cleaner’s particle CADR with the volume of the room it serves.
Your room air cleaning inputs
Ideal well-mixed particle-removal scenario.
Room air cleaning report
250 m³/hour · CADR for chosen equivalent ACH
Room volume 50 m³; ideal well-mixed model
Full result table
| Ideal elapsed min | Initial particle fraction % |
|---|---|
| 0 | 100 |
| 10 | 43.459821 |
| 20 | 18.88756 |
| 30 | 8.2085 |
| 40 | 3.567399 |
| 50 | 1.550385 |
| 60 | 0.673795 |
| 70 | 0.29283 |
| 80 | 0.127263 |
| 90 | 0.055308 |
| 100 | 0.024037 |
| 110 | 0.010446 |
| 120 | 0.00454 |
Ideal well-mixed particle-removal scenario. CADR is pollutant-specific and depends on operating speed. This does not measure outdoor ventilation, remove all gases or predict infection probability. Clearance times assume no continuing source and effective mixing.
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How to use Room Air Cleaner CADR Calculator
- Compare an air cleaner’s particle CADR with the volume of the room it serves.
- The chosen ACH is an explicit design comparison, not a prescribed personal protection target.
- The actual CADR divided by room volume gives an equivalent particle-removal air-change rate.
Worked example
A 5 ×4 ×2.5 m room is 50 m³. At a chosen five equivalent ACH, required CADR is 250 m³/hour.
Formula, accuracy & limitations
Room volume = length × width × height. Required equivalent clean-air flow = volume × chosen ACH. Actual equivalent ACH = CADR(m³/hour)/volume. Convert cfm with 1 cfm = 1.69901079552 m³/hour. Ideal 99% decay time = ln(100)/ACH hours.
Ideal well-mixed particle-removal scenario. CADR is pollutant-specific and depends on operating speed. This does not measure outdoor ventilation, remove all gases or predict infection probability. Clearance times assume no continuing source and effective mixing.
The primary result is rounded to two decimal places. Calculation tables show up to four and supporting metrics up to six. Very small nonzero values use scientific notation. Display rounding is not fed back into the arithmetic.
Official source and method context ↗Size the actual connected space
Compare an air cleaner’s particle CADR with the volume of the room it serves. Measure length, width and ceiling height in metres; open connected areas may need to be treated as part of the space. A floor-area claim based on a standard ceiling should not be silently applied to a high-ceiling room.
Keep the selected air-change assumption visible
The chosen ACH is an explicit design comparison, not a prescribed personal protection target. Multiplying it by volume gives equivalent clean-air flow in cubic metres per hour. A cleaner’s fan airflow is not automatically its CADR because filtration effectiveness also matters.
Distinguish filtration from outdoor ventilation
The actual CADR divided by room volume gives an equivalent particle-removal air-change rate. It does not tell you the outdoor-air flow, remove carbon dioxide or establish gas removal. The report therefore keeps room filtration separate from the CO₂ decay ventilation tool.
Treat a decay time as an ideal model
The ideal 99% time assumes clean-air delivery remains constant, the room is effectively mixed and no new particles are emitted. Furnishings, placement and ongoing sources can change real performance. No calculated time is a guarantee that a room is infection-free.
Frequently asked questions
Can I enter fan airflow instead of CADR?
Airflow and effective clean-air delivery are different. Use the relevant pollutant CADR at the operating setting.
Does this measure outdoor air?
Equivalent filtered-air changes are not an outdoor ventilation measurement.
Is the clearance time guaranteed?
It is an ideal no-source, well-mixed model and not a certification of room safety.
Why include ceiling height?
The calculation uses room volume, so two rooms with the same floor area can require different flows.
