Rectangular Duct Dimensions Calculator

The Rectangular Duct Dimensions Calculator is intended to assist HVAC professionals in determining the required duct dimensions and cross-sectional area based on airflow rate and target air velocity.

This tool simplifies the process of selecting appropriate rectangular duct sizes during HVAC system design and evaluation.

Operating Instructions

1. Select the preferred unit system (Metric or Imperial).
2. Enter the required airflow rate.
3. Specify the dimension of one side of the rectangular duct.
4. Enter the desired duct air velocity.
5. The calculator will determine the required duct dimension and cross-sectional area.
6. Enter user, project information, and generate a professional PDF calculation report.

Engineering Notes

• For commercial kitchen exhaust duct systems, the recommended air velocity range is 1200–1600 FPM (6–8 m/s).
• Calculations are performed according to generally accepted HVAC engineering methodologies, including the guidelines of ASHRAE and the duct design standards of SMACNA.
• The computational approach is based on standard aerodynamic and fluid mechanics principles used for determining airflow velocity and pressure losses in duct systems.