CADR Calculator for Formaldehyde & VOCs
Find the minimum Clean Air Delivery Rate for your room.
Formaldehyde and VOCs (volatile organic compounds) are invisible gases, not particles. They come from new furniture, pressed wood, paint, carpet, cleaning products, and renovation materials. HEPA filters are completely ineffective against gases — you need activated carbon.
The CADR calculation for VOCs is different from particles. Particle CADR measures particle removal speed, but gas CADR (sometimes called "odor CADR") depends on the amount and quality of activated carbon in the filter.
For new homes or freshly furnished rooms, we recommend running the purifier 24/7 on high for the first 2–4 weeks to accelerate off-gassing, then reducing to medium for maintenance. Ventilation (opening windows) is actually more effective than any purifier for initial VOC removal.
📐 How CADR Is Calculated
Formula: CADR = (Sq Ft × Ceiling × ACH) ÷ 60
AHAM recommends ≥ 4.8 ACH. Allergies: 6 ACH. Smoke/Asthma: 8 ACH.
Based on 240 CFM minimum Smoke CADR:
💡 Tips for Formaldehyde Vocs
- ✓ HEPA doesn't capture gases. You need activated carbon — and a lot of it — for formaldehyde.
- ✓ Ventilation is more effective than any purifier for initial VOC removal. Open windows first.
- ✓ Run purifier on high 24/7 for 2–4 weeks in newly furnished rooms.
- ✓ Look for purifiers with formaldehyde-specific carbon (e.g., impregnated activated carbon).