Available Static Pressure Calculator

Available static pressure is the blower external static budget left after coils, filters, terminals and other fixed losses are subtracted.

Open static pressure calculator Size ducts by airflow

available static pressure calculator manual d available static pressure duct static pressure budget

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Available duct budget

ASP = ESP_blower - filter - coil - terminals - accessories

Margin check

margin = ASP - duct_losses

Workflow

Estimate airflow, pick duct sizes, calculate equivalent-length friction losses, then compare total losses against the available static budget.

Related pages

Duct size calculator - round and rectangular duct sizing from airflow.
Duct friction loss calculator - run-level pressure loss from duct size and length.
HVAC static pressure calculator - total external static pressure and blower margin.
Grille size calculator - face velocity and free-area checks for terminals.