FullCalculator

Static Pressure Drop Calculator

Duct Friction Loss

Calculate pressure drop in straight ductwork

Formula

Delta P = f x (L/D) x (V2 / 2g) | VP = (V / 4005)^2

Frequently Asked Questions

What is static pressure?
Static pressure is the resistance to airflow in a duct system, measured in inches of water gauge (in. w.g.). It must be overcome by the fan/blower.
What causes pressure drop?
Friction from duct walls, fittings, filters, coils, and grilles all contribute. Flex duct has about 3x the friction of sheet metal.

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