What it calculates
Estimate outdoor airflow from occupancy and floor area.
Ventilation Air Calculator
Estimate outdoor airflow from occupancy and floor area using user-entered rates.
Planning and estimating aid only. Verify project requirements, manufacturer instructions, adopted codes, permits, and field conditions before performing regulated work.
HVAC planning
How to Use This Calculator
Use the field units shown below, then compare your result with the worked example. A standard stated in CFM per square foot must be converted to the tool’s per-100-square-feet input.
How the calculation works
Occupant airflow and floor-area airflow are calculated from the rates you enter and then added together.
What the result means
Use rates required by the applicable design standard or project specification.
Combine entered people and floor-area rates
Four people at an entered 5 CFM per person contribute 20 CFM. A 1,000-square-foot space at an entered 6 CFM per 100 square feet contributes 60 CFM. The sum is 80 CFM. These sample rates are arithmetic examples.
Contractor tip: A standard stated in CFM per square foot must be converted to the tool’s per-100-square-feet input. Check distribution, system effectiveness and any additional applicable requirements separately.
Verify the final quantity
This calculator uses the rates you provide; it does not choose an occupancy category or a required ventilation standard. In particular, its area-rate input is per 100 square feet, not per square foot.
Good practice: Compare the calculated quantity with plans, specifications, product packaging and current field conditions before purchasing material.