CADR Calculator for Large Rooms & Open Plan
Find the minimum Clean Air Delivery Rate for your room.
Large rooms and open-plan spaces are the hardest to air-purify effectively. The challenge is simple: more air volume means more CADR needed, and open spaces constantly mix with air from hallways, kitchens, and other connected areas.
The AHAM 2/3 rule states your purifier's CADR should be at least 2/3 of your room area in square feet. But for open-plan spaces, you must calculate the total connected area — not just the room you're placing the purifier in.
For rooms above 400 sq ft, consider two smaller purifiers placed at opposite ends instead of one large unit. This provides more even air coverage and prevents dead zones where pollutants accumulate.
📐 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 Large Room
- ✓ For open-plan spaces, include connected hallway and kitchen areas in your calculation.
- ✓ Consider two smaller purifiers instead of one large one — better coverage, fewer dead zones.
- ✓ High ceilings (9–10 ft) significantly increase volume. Always enter actual ceiling height.
- ✓ For rooms over 500 sq ft, look at commercial-grade purifiers (CADR 400+ CFM).