Enter a finite, positive room area and ceiling height.
Check model-specific procurement evidence · Request a CADR and noise-data review
Values are rounded up to whole units. Send your area, ceiling height, selected ACH, destination market and noise limit with the RFQ. Ask for CADR and noise at the same fan speed; a maximum-speed CADR does not describe sleep-mode performance.
After sizing, place it right: keep the intake and outlet unobstructed and follow the selected model's clearance instructions — see where to place an air purifier.
How the calculation works
The calculator uses room volume and your selected target. The AHAM area rule is a separate reference for standard-height rooms, not a minimum automatically enforced by every option above.
1. AHAM two-thirds rule
The Association of Home Appliance Manufacturers (AHAM) publishes the CADR standard and recommends that a purifier's CADR in CFM be at least two-thirds of the room's floor area in square feet, assuming a standard 8 ft ceiling. A 300 ft² room therefore wants a CADR of at least 200 CFM. See AHAM air filtration guidance. For wildfire smoke, AHAM gives a higher reference: smoke CADR in CFM equal to room area in ft². Particle sizing does not establish gas removal.
2. Air changes per hour (ACH)
The more flexible method sizes by how many times per hour you want the room's full air volume filtered:
Required CADR (m³/h) = room area × ceiling height × target ACH
(then divide by 1.699 to convert m³/h to CFM)
At an 8 ft ceiling, (2/3 × area × 60) / (area × 8) = 5 ACH. That equivalence changes with ceiling height. The 2, 4 and 6 ACH options are comparison scenarios, not AHAM recommendations for specific illnesses or buildings.
Worked example: the same room at different targets
A 20 m² room with a 2.4 m ceiling has a volume of 48 m³. At 4 ACH the requirement is 192 m³/h (about 113 CFM before rounding); at 5 ACH it is 240 m³/h (about 141 CFM). Raising the ceiling to 3 m raises the 4 ACH requirement to 240 m³/h. These are calculations, not measured LYL model specifications.
What this tool cannot decide: it does not predict infection risk, symptom improvement, VOC control or compliance with healthcare ventilation requirements. For gas pollutants, request pollutant-specific removal and capacity evidence. A particle CADR calculation does not replace ventilation or source control.
Sources: AHAM Verifide — CADR directory; US EPA — air cleaners in the home. Conversion: 1 CFM = 1.699 m³/h.
What the result means for an OEM order
If you are sourcing a private-label line, the calculated CADR tells you the particle CADR target for each room scenario. Product shape alone does not establish that a model meets it:
- Small rooms / desktop SKUs (bedrooms, offices): lower CADR, compact bodies — see desktop OEM.
- Living rooms / mid–large spaces: higher-airflow towers — see tower OEM.
- Halls, clinics, offices at scale: high-CADR or multi-unit — see commercial OEM.
Before publishing a coverage claim, record the room-height and ACH assumptions, test pollutant, filter configuration and operating speed. Use the CADR test-report guide to check which evidence is available for the selected model; a calculator result is not a test certificate or listing approval.
Need the tested CADR for a specific model?
Tell us your target room sizes and markets — request available model-specific performance documents, confirm any testing gaps, and ask for a dated quotation.
Request Model & CADR ReportRelated guides
- EPA wildfire-smoke CADR rule — the 2/3 baseline versus AHAM's stronger wildfire target.
- CADR vs CCM — cleaning speed vs filter life.
- AHAM vs GB/T 18801 — reading a CADR test report.
- Large-room air purifiers — high-CADR configurations.
- Air purifier models — browse the OEM/ODM range.
General sizing guidance, not a performance guarantee. Confirm the model's tested CADR and standard before publishing any room-coverage claim.
