Duct Static Pressure Calculator
Total external static pressure of a duct run: straight friction + fittings + components.
Dirty filters are the silent ESP killer: +100 Pa over a season. The fan table in the AHU manual is read against THIS number.
Formula
Duct Static Pressure Calculator is a free static pressure calculator for HVAC designers, technicians and energy auditors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Duct Static Pressure Calculator
Total external static pressure of a duct run: straight friction + fittings + components. The calculation implements ESP = L×(Pa/m) + fittings×~8 Pa + Σ components (ACCA Manual D — residential duct systems). Dirty filters are the silent ESP killer: +100 Pa over a season. The fan table in the AHU manual is read against THIS number.
How to use Duct Static Pressure Calculator
- 1Enter Total straight duct in m.
- 2Enter Friction rate in Pa/m.
- 3Enter Equivalent fittings (90° elbows).
- 4Enter Components (coil+filter+grilles) in Pa (Clean filter 40–60 · coil 50–80 · grille 10–25 Pa).
- 5Read Total static pressure instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Duct Static Pressure Calculator?
- ✓Implements the standard formula — ESP = L×(Pa/m) + fittings×~8 Pa + Σ components
- ✓Reference cited on-page: ACCA Manual D — residential duct systems
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Built-in engineering verdict flags out-of-range results instantly
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Duct Static Pressure Calculator use?+
It computes ESP = L×(Pa/m) + fittings×~8 Pa + Σ components, per ACCA Manual D — residential duct systems. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Dirty filters are the silent ESP killer: +100 Pa over a season. The fan table in the AHU manual is read against THIS number.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Duct Static Pressure Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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