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Pumps & Rotating Equipment

Pump Hydraulic Power Calculator

This calculator computes pump hydraulic power from the volumetric flow, head, fluid density and gravitational acceleration using P = ρ × g × Q × h, and shaft power by dividing the hydraulic power by the pump efficiency.

Pump hydraulic power is the energy per unit time transferred to the fluid. Shaft power accounts for pump inefficiency. This calculator determines both from operating parameters.

TypeInteractive engineering calculator

Calculator

Flow + Head + Density + Gravity + Efficiency

Default: water at ~20°C (editable)

m/s²

Standard gravity (editable)

%

Pump efficiency only (does not include motor or VFD losses)

Results
Hydraulic power2.44676 kW
Shaft power3.26235 kW

Formulas

Hydraulic power
P_hyd = ρ × g × Q × h
Shaft power
P_shaft = P_hyd / η

Diagram

Pump Hydraulic Power SchematicQ (flow)Pumph (head)η (efficiency)P_hyd = ρ × g × Q × hP_shaft = P_hyd / η

Worked example

A pump delivers 10 L/s of water (ρ = 998 kg/m³) against 25 m of head. Pump efficiency is 75%. Gravity = 9.80665 m/s².

  1. 01Convert flow: 10 L/s = 0.01 m³/s
  2. 02P_hyd = 998 × 9.80665 × 0.01 × 25
  3. 03P_hyd = 2,446.7 W ≈ 2.447 kW
  4. 04P_shaft = 2,446.7 / 0.75 = 3,262.3 W ≈ 3.262 kW
Result

Hydraulic power is approximately 2.45 kW. Shaft power at 75% efficiency is approximately 3.26 kW.

FAQ

Does this include pump curves?
No. You must supply the operating point (flow and head) directly. Pump curve lookup is not implemented.
Does this calculate NPSH?
No. Net Positive Suction Head calculation is outside the scope of this calculator.
Does this assume water?
No. Density must be supplied. A default of 998 kg/m³ is shown for convenience but is clearly labelled and editable.
Is the efficiency value pump efficiency or overall efficiency?
It is pump efficiency only. Motor, VFD, and coupling losses are not included unless you account for them externally.
Is this a heat duty calculator?
No. This calculator computes pump hydraulic and shaft power only.

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