Free Mechanical / HVAC calculator

Pump hydraulic power calculator

Calculate hydraulic power and estimated shaft power from flow, head or pressure difference, density and pump efficiency.

Enter the project values

All values remain in your browser. Review the assumptions before using the result.

Your result will appear here.Calculate to see the outputs, formula and substituted working.

How the calculation works

Hydraulic power converted to estimated shaft power using user-entered pump efficiency.

Formula

Ph = ρgQH = QΔp; Pshaft = Ph ÷ η

Worked example

Flow5 L/s

Pressure difference200 kPa

Pump efficiency70%

Expected power1.000 kW hydraulic / 1.429 kW shaft

Assumptions and limitations

Assumptions

Fluid density and pump efficiency are represented by entered values.
The duty point is steady-state.

What this does not check

Does not include motor efficiency, pump curve, NPSH or control margin.
Does not select a pump or establish the system curve.

Formula version: 1.0 · Last reviewed: 16 August 2026

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Engineering basis: first-principles calculation using user-entered project data. The calculator does not choose design criteria or replace the complete project-specific engineering design.

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