Understanding CFM Calculations
This calculator estimates the CFM (Cubic Feet per Minute) required for ventilation or HVAC systems based on room volume, air changes per hour (ACH), and application type, with imperial or metric units.
Proper airflow ensures adequate ventilation and comfort. CFM is calculated as room volume multiplied by ACH, divided by 60 minutes. Duct sizing is estimated assuming standard air velocity.
Example CFM Requirements
| Room Size | Application | ACH | CFM | Scenario |
|---|---|---|---|---|
| 20x20x8 ft | Residential | 4 | 533 CFM | Living room, moderate ventilation |
| 50x30x10 ft | Commercial | 8 | 4000 CFM | Office space, high ventilation |
| 100x50x12 ft | Industrial | 12 | 12000 CFM | Warehouse, heavy ventilation |
How to Use the CFM Calculator
- Select the unit system (imperial or metric).
- Enter the room dimensions (length, width, ceiling height).
- Specify the air changes per hour (ACH) or select an application type to set a typical ACH.
- Click "Calculate CFM" to view the room volume, required airflow, and suggested duct size.
CFM vs. Air Changes per Hour
Required airflow for different ACH values based on input room volume.
Frequently Asked Questions
What is CFM?
CFM (Cubic Feet per Minute) measures the volume of air moved by an HVAC or ventilation system per minute.
What is an air change per hour (ACH)?
ACH is the number of times the entire volume of air in a room is replaced in one hour, varying by application (e.g., 2–6 for homes, 6–12 for offices).