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Calculators / Airflow

Airflow

Duct Airflow CFM Calculator

Create a first-pass total airflow target to discuss during commissioning and balancing.

Your planning inputsUpdates automatically
tons
Use the selected system size.
CFM/ton
Manufacturer setup may vary by climate and humidity target.
Used only to show an equal-share planning target.

Estimated result

1,200 total CFM

Equal return-grille screening target: 600 CFM per grille. Final duct design requires pressure and friction calculations.

How to use this estimate

  • The total is a setup target; final airflow must follow manufacturer data and measured static pressure.
  • Equal return-grille allocation is only a quick screening number.
  • Ask for documented total external static pressure and delivered airflow at commissioning.

Transparent method

We expose the planning formula so you can challenge it and replace assumptions with local evidence.

nominal tons × target CFM per ton

What this calculator cannot see

  • Duct sizing requires friction rate, length, fittings, registers, filters, and equipment pressure drop.
  • Do not adjust blower settings without qualified service.

Professional verification

Use this result to prepare questions and compare scenarios. Final equipment selection, electrical work, refrigerant work, combustion, duct design, and permitting should be handled by qualified professionals following local codes and manufacturer instructions.