CFM Airflow Calculator
Who it's for: HVAC designers, service technicians, and commissioning teams.
Calculator Inputs
Quick Summary
- Built for: HVAC designers, service technicians, and commissioning teams.
- Key outputs: Room volume (cu ft), Required CFM, and more.
- Use this page for early planning estimates before final code and manufacturer verification.
Inputs
- Room length (ft)
- Room width (ft)
- Room height (ft)
- Target ACH
Outputs
- Room volume (cu ft)
- Required CFM
- Airflow per square foot
How this calculator estimates results
- Computes room volume from length, width, and height inputs.
- Applies ACH (air changes per hour) to estimate required airflow with the formula CFM = Volume × ACH ÷ 60.
- Returns rounded CFM and airflow-per-area values for quick planning.
Cross-check assumptions with Duct Size Calculator for a more complete planning workflow.
Common ranges and tips
- Use field-verified room dimensions for better volume accuracy.
- Confirm ACH assumptions by occupancy and space use, not generic rules alone.
- Pair CFM estimates with the Duct Size Calculator for branch planning.
- Validate final airflow with balancing measurements after installation.
Related Calculators
FAQ
No. Target ACH varies by use case and project requirements, so choose assumptions carefully and validate against project standards.
No. This estimator calculates target airflow only; duct friction, leakage, and fan performance are separate checks.
They should generally be balanced at the system level, then confirmed with field measurements and commissioning practices.
Disclaimer: Use results for planning only. Final design and installation decisions must follow local code and manufacturer documentation.
Back to HVAC hub