Pump Power Calculator

Estimate hydraulic, shaft and electrical power at one stated pump duty point, then turn the electrical result into a transparent annual energy and cost estimate.

Hydraulic power4.078 kWρgQH
Shaft power5.437 kWAfter pump efficiency
Electrical input6.041 kW8.102 hp · before drive losses
Annual energy24.166 MWh/yearAt the entered annual operating hours
Annual electricity cost2,899.863 currency/yearUses your entered electricity price

Scope: One-duty-point estimate only. Annual energy assumes this duty and electrical input remain constant for every entered operating hour. It does not select a pump, create a system curve, check NPSH/cavitation, account for viscosity correction, variable-speed drive losses, tariffs or provide motor sizing.

Method

Hydraulic power is P = ρgQH. The page divides by pump efficiency for shaft power, then by motor efficiency for electrical input. Annual energy is electrical input multiplied by the operating hours you enter.

Worked example

Water at 998 kg/m³, 50 m³/h and 30 m head needs about 4.08 kW hydraulic power; with 75% pump and 90% motor efficiency, electrical input is about 6.05 kW. At 4,000 annual operating hours, that is approximately 24.2 MWh/year before any variable-duty or tariff effects.

Important limits

Total dynamic head must represent the actual system at the selected flow. The annual estimate assumes a constant duty point and a single energy price. Select equipment from the manufacturer curve and separately verify NPSH, operating range, compatibility, drive losses, demand charges and margins.

Reference

U.S. Department of Energy: pumping-system assessment

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Frequently asked questions

What pump power equation does this calculator use?
Hydraulic power is P = ρgQH. The calculator divides it by pump efficiency for shaft power and by motor efficiency for electrical input.

What should total dynamic head include?
Use the total head at the stated flow: applicable static lift, pressure requirements and friction or fitting losses. Establish it from the actual system rather than treating it as a pump selection result.

How is annual pump energy estimated?
Electrical input power is multiplied by the annual operating hours you enter. The cost result then multiplies that energy by your entered electricity price, in your own currency unit.