Homeowner planning tool
Room ventilation airflow calculator
Calculate airflow from room volume and a target number of air changes per hour.
Your inputs
Starts with example figures. Replace them with your own values; results update as you type. These examples are not equipment recommendations or current utility prices.
Example calculation
Sample estimate
- Room volume
- 960
- Airflow at the entered ACH
- 8
Cubic feet
Cubic feet per minute (CFM)
Check every input and read the assumptions below. Unchanged fields may still contain example figures.
What the result means
Assumptions and limits
This is volume arithmetic, not a whole-house ventilation design or code-compliance check. It does not assess occupancy, pollutants, exhaust, makeup air, duct losses or combustion safety.
Discuss indoor air and ventilationHow this calculator works
Room volume = length × width × height. Airflow in cubic feet per minute (CFM) = volume × air changes per hour ÷ 60.
Before you decide
What your results mean
Use the result with its assumptions and limitations.
What does the room example calculate?
For a rectangular room, volume is length × width × height; CFM is that volume × the entered air changes per hour ÷ 60. The editable example demonstrates that arithmetic. Its ACH is not a recommended target, code requirement or whole-home system design.
How does a simple airflow example work?
A 10-by-12-foot room with an 8-foot ceiling has 960 cubic feet. At an illustrative 0.5 air changes per hour, the arithmetic gives 8 CFM. This example is not a recommended ventilation target or a code check.
What is missing from a whole-home design?
The calculation does not assess occupancy, pollutants, exhaust, makeup air, duct losses or combustion safety. Those questions need a complete ventilation assessment.
Your next step
Discuss your home’s equipment
Bring the estimate and your questions. Equipment selection needs more information about your home than a calculator can collect.
