Pump Power & Efficiency Calculator
Calculate hydraulic power, pump shaft power, estimated electrical input and a motor sizing screening value.
“I know the flow and head. What shaft kW and motor input should I expect?”
Pump power reference
P_h = ρ g Q HP_shaft = P_h / η_pumpP_in = P_shaft / η_motorPump energy chain
Duty point and fluid
Use the expected operating flow and total dynamic head.
Pipe size and viscosity affect the head required by the system. Once total dynamic head is known, pump hydraulic power depends on flow, head and density. Use the Pipe Pressure Drop calculator first when you still need to establish the system head.
Efficiencies and motor comparison
Use the pump and motor data at the actual operating duty point where available.
Power through the system
Includes 15% margin on shaft power.
Rating margin: 3.3 kW. Confirm the pump curve, absorbed-power curve, overload conditions and motor service duty.
Hydraulic power = ρgQH. Shaft power divides by pump efficiency; estimated electrical input also divides by motor efficiency.
Save the calculation, not just the number.
Copy a permalink that reloads these inputs, or download a PDF record with inputs, visible results, assumptions, a sensitivity note, date and disclaimer.
A calculator can show the arithmetic. It cannot establish every requirement that applies.
Confirm the actual equipment, loading, materials, condition, jurisdiction, contractual requirements, standard edition and current project documentation before using the result for design, repair, testing or lifting decisions.
Ask an engineer about this calculation →