CADR Calculator for Wildfire Smoke

Find the minimum Clean Air Delivery Rate for your room.

Wildfire smoke contains ultrafine PM2.5 particles (0.1–1 μm) that penetrate deep into lungs. During a smoke event, outdoor AQI can spike to 300+ (Hazardous), and indoor PM2.5 rises within hours if your home isn't sealed.

Standard AHAM's 4.8 ACH isn't enough for wildfire smoke. We recommend 6 ACH minimum, and 8 ACH if you're in an active fire zone. This calculator uses the higher standard to ensure your purifier can actually keep up during peak smoke events.

Also critical: your purifier needs a thick activated carbon filter, not just HEPA. Carbon captures the VOCs and toxic gases that accompany wildfire particles. HEPA alone won't protect you from the full spectrum of wildfire pollutants.

Length (ft)

Width (ft)

Ceiling (ft)

ACH: 6

Minimum CADR Required

240

CFM

Room: 180 sq ft · Vol: 1,440 cu ft

Dust CADR

240

CFM

Pollen CADR

240

CFM

Smoke CADR

240

CFM

🏠 Your room, to scale (top view)

180 ft² Purifier

15 ft × 12 ft floor plan · purifier placed in a corner

Filters all the air in your room 4× per hour — about once every 15 min.

That's roughly a 17 m² bedroom-sized space.

🔍 Already have a purifier? Select it below:

📐 How CADR Is Calculated

Formula: CADR = (Sq Ft × Ceiling × ACH) ÷ 60

AHAM recommends ≥ 4.8 ACH. Allergies: 6 ACH. Smoke/Asthma: 8 ACH.

Recommended Air Purifiers

Based on 240 CFM minimum Smoke CADR:

💡 Tips for Wildfire Smoke

✓ Close all windows and doors before running the purifier during smoke events.
✓ HEPA + activated carbon is the minimum for wildfire smoke. Avoid HEPA-only purifiers.
✓ Check PurpleAir or AirNow for real-time outdoor AQI to decide purifier speed.
✓ Run on maximum for the first hour, then reduce to medium once AQI stabilizes indoors.

CADR Calculator for Wildfire Smoke

📐 How CADR Is Calculated

💡 Tips for Wildfire Smoke

📚 Related Guides