HVAC Static Pressure Calculator

Inputs

Return duct drop (Δp_r)

Return-side duct and fitting pressure drop at design airflow.

Filter drop (Δp_f)

Clean or design filter pressure drop, not the final dirty-filter limit unless that is your design basis.

Coil / heat exchanger drop (Δp_c)

Evaporator coil, hot-water coil, heat exchanger or similar component pressure drop.

Supply duct drop (Δp_s)

Supply-side duct and fitting pressure drop at design airflow.

Registers / diffusers (Δp_t)

Terminal device, grille, register or diffuser pressure drop.

Other accessories (Δp_o)

Humidifier, damper, silencer, UV rack, economizer or other added pressure drop.

Available / rated static (ESP)

External static pressure available from the blower table at design airflow.

Default result

Total external static(TESP)

120Pa

Pass

within the entered available static pressure

Also computed

Static margin(ESP - TESP)5Pa

remaining blower static after listed losses

Percent of available static(%ESP)96%

Duct-only drop(Δp_duct)60Pa

Filter/coil/accessory drop(Δp_acc)60Pa

Return-side total(Δp_return)50Pa

Supply-side total(Δp_supply)70Pa

Method notes 3 notes

Total external static pressure is the sum of external pressure drops at the design airflow.
Use component pressure drops from manufacturer data at the actual airflow. Filter, coil and grille drops change with flow and loading.
Do not add a measured blower-table static value on top of TESP; compare the summed losses to the blower table available static at the target airflow.