Fan Power Calculator
Shaft and electrical power to move an airflow against a static pressure.
SFP (specific fan power, W per L/s) is the modern code metric โ under 1.5 W/(L/s) is good practice. High static, not airflow, is usually the energy villain.
Formula
Fan Power Calculator is a free fan power for HVAC designers, technicians and energy auditors โ 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 Fan Power Calculator
Shaft and electrical power to move an airflow against a static pressure. The calculation implements P_air = Qยทฮp; P_shaft = P_air/ฮท_fan (AMCA 208; EN 16798 SFP classes). SFP (specific fan power, W per L/s) is the modern code metric โ under 1.5 W/(L/s) is good practice. High static, not airflow, is usually the energy villain.
How to use Fan Power Calculator
- 1Enter Airflow in L/s.
- 2Enter Total pressure rise in Pa.
- 3Enter Fan total efficiency in %.
- 4Enter Motor+drive efficiency in %.
- 5Read Air power, Shaft power, Electrical input instantly โ no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Fan Power Calculator?
- โImplements the standard formula โ P_air = Qยทฮp; P_shaft = P_air/ฮท_fan
- โReference cited on-page: AMCA 208; EN 16798 SFP classes
- โOne-click SI โ Imperial toggle โ values convert in place, physics stays in SI
- โLive worked example: the substitution recomputes from your numbers
- โRuns entirely in your browser โ nothing uploaded, free forever
Frequently asked questions
What formula does the Fan Power Calculator use?+
It computes P_air = Qยทฮp; P_shaft = P_air/ฮท_fan, per AMCA 208; EN 16798 SFP classes. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
SFP (specific fan power, W per L/s) is the modern code metric โ under 1.5 W/(L/s) is good practice. High static, not airflow, is usually the energy villain.
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 Fan Power Calculator free to use?+
Yes โ 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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