Calculate CFM (Cubic Feet per Minute), air changes per hour (ACH), and duct sizing for HVAC, ventilation, and air quality applications.
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CFM (Cubic Feet per Minute) is the standard unit for measuring airflow in HVAC and ventilation systems. Our calculator helps you determine proper ventilation requirements, air changes per hour, and duct sizing for any space.
CFM measures the volume of air flowing past a point in one minute. It's essential for sizing fans, air handlers, and ductwork in residential and commercial HVAC systems. Air Changes per Hour (ACH) indicates how many times the air in a room is completely replaced each hour.
CFM & ACH Formulas
CFM = (Volume × ACH) / 60, ACH = (CFM × 60) / VolumeEnsure adequate fresh air for healthy indoor environments.
Select properly sized fans and air handlers for your space.
Avoid over-ventilating which wastes energy and increases costs.
Size exhaust fans for moisture control (typically 8 ACH).
Calculate range hood CFM for effective cooking fume removal.
Ensure adequate airflow for IT equipment heat dissipation.
Size ventilation for dust and fume extraction.
ACH requirements vary by room type: bedrooms need 2-4 ACH, bathrooms 6-8 ACH, kitchens 7-8 ACH, and server rooms 10-20 ACH. Check ASHRAE guidelines for specific applications.