Determine proper ventilation for any room. Enter dimensions, pick the room type, and get the CFM you need. Learn more
Determine proper ventilation for any room. Enter dimensions, pick the room type, and get the CFM you need.
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CFM (cubic feet per minute) is the standard measure of air volume moving through a space. This calculator gives you a fast, accurate result based on room dimensions and air change requirements.
How to calculate CFM:
Once you know the CFM, use the duct size calculator to pick the right duct for that airflow. If you need to size the whole system first, start with the HVAC load calculator.
CFM stands for cubic feet per minute. It measures the volume of air moving through a space. According to ASHRAE Standard 62.2, residential ventilation must deliver a minimum of 0.35 air changes per hour to maintain acceptable indoor air quality. Getting the CFM right ensures a room stays comfortable, meets building ventilation codes, and maintains the right temperature.
ACH is how many times the air in a room is fully replaced in one hour. CFM is the volume of air moving per minute. To convert: multiply the room volume by ACH and divide by 60. This calculator handles that math automatically.
Hot spots, stuffy air, and condensation on windows are clear signs. If your space feels uncomfortable despite the HVAC running, the vents may not be delivering enough CFM for the square footage.
These rooms require higher airflow to remove moisture and odors. Per ASHRAE 62.2 and most building codes, bathrooms typically need 50–100 CFM and kitchens often need 100–300 CFM depending on the range hood and ventilation setup. The EPA estimates that poor indoor ventilation contributes to 50% higher pollutant concentrations indoors than outdoors. Getting these numbers right is vital for preventing mold and maintaining air quality.
Yes. CFM is based on room volume, not just floor area. A room with 10-foot ceilings has 25% more volume than the same room with 8-foot ceilings, and needs proportionally more airflow.
