HVAC Duct Static Pressure & CFM Calculator

■ Duct Geometry INPUT

Shape Round Rectangular Duct Length (ft) Duct Material Galvanized Steel Smooth Metal Flex Duct Duct Board Custom C-f

■ Airflow INPUT

Target CFM

■ Fittings & Fittings Loss INPUT

Each fitting is converted to equivalent straight-duct length using K-factors × velocity pressure.

+ Add Fitting Accessories (damper, grille, etc.) — total equivalent length (ft)

■ Results OUTPUT

■ Rectangular ↔ Round CONVERT

Equivalent diameter for equal friction between round and rectangular ducts.

Convert