⏱️ Fact-checked and updated by our editorial team in July 2026. Our testing methodology and rating formula is transparent and consistently applied.

What Does CADR Mean on an Air Purifier? (Smoke vs Dust vs Pollen Ratings)

CADR is the most important air purifier spec — but almost no one explains it right. Learn how to read CADR numbers and spot marketing lies.

What CADR Actually Is (in 30 seconds)

CADR (Clean Air Delivery Rate) is the amount of clean air a purifier outputs, measured in cubic feet per minute (CFM), independently tested by the AHAM trade group. Three numbers: smoke, dust, pollen. Bigger = faster cleaner air.

Smoke CADR, Dust CADR, Pollen CADR: Which Matters Most?

• Smoke CADR = smallest particles: 0.09–1 μm. Most important number → performance fine PM2.5 wildfire, fine dust, viruses.
• Dust CADR = ~0.5–3 μm. Household dust and mite allergen bits.
• Pollen CADR = ~5–30 μm. Giant particles mostly easy for any HEPA. Usually the biggest number brand.

Look at smoke CADR first when comparing. That’s the hardest job.

Calculating Room Size from CADR

AHAM formula: sq ft = CADR × 1.55. A purifier 250 CFM smoke CADR → 250 × 1.55 ≈ 388 sq ft. That assumes 5 air changes/hour — the allergy minimum.

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