Calculator · Fluid Mechanics
Pump Head & Power Calculator
A pump adds head to the fluid, and the power that takes follows from the flow rate it does so at. Power delivered to the fluid and power the driver must supply are two different numbers, and they are never merged here.
Inputs
Must satisfy 0 < η ≤ 100 %. Without it, only the power delivered to the fluid can be reported.
Results
Hydraulic power P = ρ g Q h_p
The driver must supply 3.92266 kW at the stated efficiency.
| Fluid density ρ | 1000 kg/m³ |
|---|---|
| Volumetric flow rate Q | 0.02 m³/s |
| Pump head h_p | 15 m |
| Hydraulic power P_hyd | 2.942 kW |
| Shaft power P_in = P_hyd/η | 3.92266 kW |
| Efficiency η | 75 % |
Assumptions
- · Steady, incompressible flow through the pump.
- · Hydraulic power is delivered to the fluid; shaft power is what the driver must supply.
- · No pump curve, operating point, NPSH or motor selection is modelled.
Explore in the Lab
The pump head appears as the step up in the energy grade line.
Technical reference
P_hyd = ρ g Q h_p
P_in = P_hyd / η
- P_hyd
- hydraulic power delivered to the fluid[W]
- P_in
- shaft power the driver must supply[W]
- Q
- volumetric flow rate through the pump[m³/s]
- h_p
- head the pump adds to the fluid[m]
- η
- pump efficiency, 0 < η ≤ 1[-]
- g
- gravity, 9.80665 m/s²[m/s²]
Hydraulic power is what reaches the fluid; shaft power is what the driver delivers. Quoting one as the other is the most common error in pump sizing.
The head here is the head the pump actually adds. Working out the head a system demands is an energy-equation question, and a pipe system's losses belong to pipe flow.
No pump curve, operating point, NPSH, cavitation margin or motor selection is modelled. This is duty arithmetic, not pump selection.