Pump Power Calculator

Calculate hydraulic and shaft power for a pump from flow, head and efficiency.

About Pump Power Calculator

Hydraulic power is the useful work delivered to the fluid; dividing successively by pump and motor efficiency gives the electrical input. The product of the two efficiencies is what determines running cost. Pumping is often the largest electrical load in a facility, and annual energy at continuous duty dwarfs the capital cost of a better pump.

Formula

Pump Power

Hydraulic power = ρ g Q H; shaft power divides by pump efficiency, electrical by motor efficiency

wire-to-water efficiency: Product of pump and motor efficiency

Worked example

With the default values below, Pump Power Calculator returns Shaft Power Required of 3.4063. Change any input above and every figure here is recalculated in your browser.

Inputs used

Flow rateminimum 0 L/s: 10 L/s
Total headminimum 0 m: 25 m
Pump efficiencyaccepts 0–100 %: 72 %
Motor efficiencyaccepts 0–100 %: 92 %
Fluid densityminimum 0.01 kg/m3: 1,000 kg/m3

Results

Shaft Power Required: 3.4063 kW
Hydraulic Power Delivered: 2.4525 kW
Electrical Power Drawn: 3.7024 kW
Annual Energy at Continuous Duty: 32,433 kWh
Overall Wire-to-Water Efficiency: 66.24%

Step by step

1Values used
2Pump Power
3Shaft Power Required= 3.4063 kW
4Hydraulic Power Delivered= 2.4525 kW
5Electrical Power Drawn= 3.7024 kW
6Annual Energy at Continuous Duty= 32,433 kWh
7Overall Wire-to-Water Efficiency= 66.24

Assumptions and limits

The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Pump Power calculated?

Hydraulic power = ρ g Q H; shaft power divides by pump efficiency, electrical by motor efficiency Hydraulic power is the useful work delivered to the fluid; dividing successively by pump and motor efficiency gives the electrical input. The product of the two efficiencies is what determines running cost.

Why does Pump Power matter?

Pumping is often the largest electrical load in a facility, and annual energy at continuous duty dwarfs the capital cost of a better pump.

What values do I need to enter?

This calculator takes 5 inputs: Flow rate, Total head, Pump efficiency, Motor efficiency, Fluid density. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.