Cannabis Grow Room Airflow Calculator
Circulation and exhaust CFM for a cannabis grow room.
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ⓘ Live results
Results
- Internal circulation airflow
- 1,500 CFM
- Exhaust airflow for lighting heat
- 1,896 CFM
- Room volume
- 3,000 cu ft
Quick answer
Cannabis grow rooms need internal air circulation of about 1 full room air exchange every 1-3 minutes plus exhaust sized to the lighting heat load.
Circulation CFM = volume / exchange time (min); Exhaust CFM = (W x 3.412)/(1.08 x dT)
How to use the Cannabis Grow Room Airflow Calculator
- 1Compute room volume for circulation fan sizing (aim for a 1-3 minute full exchange).
- 2Total the wattage of grow lights and other heat-producing equipment.
- 3Convert that heat load to exhaust CFM at your allowable temperature rise.
Worked example
Using the values the calculator loads with:
Inputs
- Room length20 ft
- Room width15 ft
- Ceiling height10 ft
- Total lighting load6000 W
- Allowable temp rise10 F
Results
- Internal circulation airflow1,500 CFM
- Exhaust airflow for lighting heat1,896 CFM
- Room volume3,000 cu ft
Frequently asked questions
Do I need CO2 supplementation ventilation separately?
Yes — CO2-enriched rooms should minimize outdoor air exchange during light hours except for heat removal.
Dehumidification?
Flowering stage transpiration adds a large latent load — size dehumidifiers separately from sensible cooling.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.