CFM Calculator – Calculate Cubic Feet per Minute
Calculate CFM (Cubic Feet per Minute) for HVAC systems. Determine proper airflow requirements based on room dimensions, air changes per hour, and duct sizing.
Step 1: Room Dimensions
Understanding Room Volume
Room volume is calculated by multiplying length × width × height. This is the first step in determining proper airflow requirements for HVAC systems.
Step 2: Ventilation Requirements
About Air Changes Per Hour (ACH)
ACH represents how many times the air in a room is replaced per hour. Higher values are needed for kitchens, bathrooms, and gyms. Lower values are suitable for bedrooms and offices.
CFM Calculation Results
Required CFM (Cubic Feet per Minute)
CFM Requirements by Room Type
| Room Type | Recommended ACH | Typical CFM | CFM per Person | Minimum CFM |
|---|
Duct Sizing Guide
CFM Calculation Formula
CFM = (Room Volume × ACH) ÷ 60
The CFM is calculated by multiplying the room volume (cubic feet) by the required air changes per hour (ACH), then dividing by 60 to convert hours to minutes.
Duct Sizing Table
| Duct Diameter | Air Velocity at 240 CFM | Max Recommended CFM | Static Pressure |
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