Engineering · HOKO Export Team · 2026-03

CADR — Clean Air Delivery Rate — is the single number that positions an air purifier, and the easiest number to inflate. Before you sign a PO, spend five minutes inside the test report. Here is what matters.

What CADR actually measures

Under AHAM AC-1 (and the parallel GB/T 18801), a test chamber is seeded with a pollutant — tobacco smoke, dust or pollen for particles; formaldehyde for gas — and the decay rate with the machine running is compared against natural decay. The difference, scaled by chamber volume, is the CADR in m³/h (or CFM). It measures the whole system: filter media, airflow path, fan, sealing.

Five fields to check in any report

  1. The standard. AHAM AC-1-2020 (US) or GB/T 18801 (China) are the credible frames. A report without a stated standard is a datasheet, not a test.
  2. Chamber volume. 30 m³ is the common reference chamber; 81 m³ chambers exist for large commercial units. CADR is only comparable within similar chamber conditions.
  3. Measured vs. rated. Compare the report's measured CADR against the catalog number. Example from our files: the KJ410 platform measures 395 m³/h particles against a 400 m³/h rating — that 1–2% gap is what honest engineering looks like.
  4. The exact configuration. Model number, filter type, fan setting, voltage. A CADR measured on a different filter or a prototype board does not transfer to your SKU.
  5. The lab. CMA/CNAS-accredited labs in China, or AHAM-recognized programs in the US. Ask for the lab's accreditation reference.

From CADR to room size

The AHAM rule of thumb: room area (m²) ≈ CADR (m³/h) × 0.07–0.12, assuming standard ceiling height and 2–5 air changes per hour. That is why our platforms publish ranges (e.g. 42–72 m² for 600 m³/h) rather than a single flattering number.

What to request from your supplier

The full PDF, not a screenshot of the summary line. Our test report center lists reports by model — CADR, noise at max and sleep mode, formaldehyde removal, and hygiene suites for pet platforms — shared in full under NDA. If a supplier hesitates at that sentence, you have learned something valuable for free.