Available Static Pressure Calculator
Available static pressure for duct design.
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ⓘ Live results
Results
- Available static for ductwork
- 0.2 in wc
- Total fixed losses
- 0.3 in wc
- Status
- OK — proceed to friction rate calc
Quick answer
Available static pressure equals the blower's total external static rating minus the pressure drops of the coil, filter and other fixed components.
Available SP = total external SP - component losses
How to use the Available Static Pressure Calculator
- 1Find the blower's rated total external static pressure (TESP) from the equipment spec sheet.
- 2Subtract the coil, filter and any other fixed component losses at design airflow.
- 3Use the remaining available static pressure to calculate the design friction rate for the ducts.
Worked example
Using the values the calculator loads with:
Inputs
- Blower total external static0.5 in wc
- Coil pressure drop0.15 in wc
- Filter pressure drop0.1 in wc
- Other fixed losses0.05 in wc
Results
- Available static for ductwork0.2 in wc
- Total fixed losses0.3 in wc
- StatusOK — proceed to friction rate calc
Frequently asked questions
What if available static is negative?
The fixed components already exceed the blower's capacity — a lower-pressure-drop filter or larger coil is needed before duct design can proceed.
Typical TESP for residential systems?
Often 0.5 in wc, though high-efficiency variable-speed blowers can be rated higher.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.