Air purifier basics: CADR and testing standards
An introduction to clean air delivery, the main air purifier testing standards, and room-sizing calculations.
Published
Standards checked on 11 October 2026.
New to air purifier specifications? Start with CADR and the testing methods behind the numbers, then use the model comparison to compare performance and noise at different fan settings.
For the technology inside the purifier, read HEPA, washable electrostatic, electret, and disinfection.
CADR
Clean Air Delivery Rate (CADR) describes an air cleaner’s effective delivery of clean air for a particular pollutant. Higher CADR means faster removal under the test conditions. AHAM reports separate results for smoke, dust, and pollen; one number should not stand in for all three. AHAM’s explanation of CADR.
Use m³/h throughout a comparison. Some reports use cubic feet per minute (cfm): 1 cfm ≈ 1.699 m³/h. Converting units does not convert one testing standard into another.
Airflow and CADR are different quantities. Airflow tells you how much air passes through the machine; CADR accounts for cleaning performance. A filter’s capture percentage alone does not tell you how quickly the complete purifier cleans a room.
Different testing standards
| Standard or program | What it measures | How to use it in a comparison |
|---|---|---|
| ANSI/AHAM AC-1 | Whole-device particle removal, with separate smoke, dust, and pollen CADR results. | Compare the same pollutant and fan setting. Record the edition used in the report. |
| GB/T 18801 | China’s air cleaner standard. Product reports may quote particle CADR or CADR for a named gas. | Record the edition and pollutant explicitly; keep particle and gas results separate. |
| JEMA / JEM1467 | Japanese air purifier test references used in manufacturer specifications. | Preserve the reported quantity: airflow, room coverage, and a manufacturer-converted CADR are distinct. Daikin describes its MCK70Z rating as converted from JEM1467 test values. Daikin’s specification notes. |
| IEC 63086-2-1:2024 | Performance testing for reduction of particulate pollutants by household and similar air cleaners. | Record the particle test, operating setting, and report details before comparing results. |
| ISO 29463 / EN 1822 filter classification | Performance and classification of high-efficiency filters. | Use to assess the filter claim; this does not supply the complete purifier’s room-cleaning CADR. |
| AHAM AC-2 / ISO 3741 acoustic testing | Acoustic testing used to characterize air cleaner noise. | Identify the acoustic quantity reported. Sound power and sound pressure values are not interchangeable. |
AHAM Verifide is a verification program using the AC-1 method, with independent laboratory testing. A manufacturer saying “tested to AC-1” does not by itself establish participation in that program. AHAM’s testing and verification explanation.
China’s official standards register lists GB/T 18801-2022 as current, effective from 1 May 2023, and the 2015 edition as withdrawn. Keep the original edition on older product reports rather than relabeling their results as 2022 tests. Official GB/T 18801 register. Intertek also offers GB/T 18801 testing for chemical gases, which illustrates why the pollutant must accompany a CADR value. Intertek’s testing scope.
IEC’s particle-performance method is described in its IEC 63086-2-1:2024 listing. Filter classifications are covered by ISO 29463-1:2024; acoustic methods are described in Intertek’s air cleaner sound testing information.
When comparing models, treat results from different standards as separate evidence. A shared unit is useful, but a fair comparison also needs a matching pollutant, operating mode, and test setup. Do not apply a fixed multiplier to estimate an AHAM result from a GB/T result.
CADR and room size
For a room-volume check, divide CADR in m³/h by room volume in m³ to estimate equivalent clean-air changes per hour under an idealized mixing assumption. For example, a 20 m² room with a 2.5 m ceiling has a volume of 50 m³; 250 m³/h corresponds to 5 equivalent clean-air changes per hour. This is a sizing calculation, not a promise of identical performance in every room. AHAM’s suggested room sizes use 4.8 air changes per hour. AHAM’s room-sizing explanation.