Pump Hydraulic Power Calculator
Enter fluid density, flow rate and head to compute the hydraulic power P = ρ·g·Q·H required by a pump.
Input Data
Results
At a glance:The hydraulic power (also called water horsepower) is the rate of increase of the fluid's mechanical energy: P_hyd = ρ·g·Q·H, where ρ is density, g gravity, Q the volumetric flow rate and H the total head (elevation + pressure + velocity head the pump supplies). It is the minimum shaft power the pump must provide; the actual required shaft power is P_shaft = P_hyd/η where η is pump efficiency (often 0.6–0.85). This tool returns P in W and kW from ρ, Q, H (and g).
Formula
P_hyd = ρ·g·Q·H
Shaft power: P_shaft = P_hyd/η
$$P = \rho\,g\,Q\,H$$How to Use
- Enter fluid density ρ, flow rate Q and head H.
- The calculator returns hydraulic power in W and kW.
Case Studies
Water pump
ρ = 1000, Q = 0.02 m³/s, H = 20 m.
P = 1000×9.81×0.02×20 = 3924 W ≈ 3.9 kW.
With η=0.7, motor ≈ 5.6 kW.
FAQ
Is this the motor power I need?
No — it's the ideal hydraulic power. The motor must supply P_hyd/η; with η≈0.7 a 7 kW hydraulic load needs a ~10 kW motor.
What counts as head H?
The total head the pump must overcome: static lift plus friction and pressure requirements (in meters of fluid).
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References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.