Pump Power Calculator
Calculate hydraulic and shaft power for a pump from flow rate, head, and efficiency.
How it works
- 1Enter the flow rate, total head (static lift plus friction losses), and pump efficiency.
- 2The calculator computes hydraulic power P = ρ·g·Q·H.
- 3Shaft (input) power is hydraulic power divided by the fractional efficiency.
Use cases
- Sizing electric motors for water-supply and irrigation pumps.
- Estimating energy use of HVAC chilled- and heating-water pumps.
- Comparing pump options when designing process pipework.
Frequently asked questions
What is hydraulic power?
The useful power delivered to the fluid: P = ρ·g·Q·H (ρ = 1000 kg/m³ for water, g = 9.807 m/s²). At 10 L/s and 20 m it is about 1962 W ≈ 1.96 kW.
How does efficiency affect shaft power?
Shaft power = hydraulic power ÷ efficiency. At 70% efficiency, the worked example needs ≈ 1962 ÷ 0.70 ≈ 2803 W ≈ 2.8 kW.
What does total head include?
Static elevation, velocity head, and friction losses in pipes, fittings, and valves. Always use total head, not just elevation, for power sizing.
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