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Pump Power Calculator — Flow, Head, Density & Efficiency

Calculate hydraulic power and estimated pump input power from flow rate, total head, fluid density and overall efficiency using P = ρgQH.

Flow (m³/h)Total head (m)Fluid density (kg/m³)Overall efficiency (%)

Estimated input power

5.837 kW

Hydraulic power: 4.086 kW

P = ρgQH; input power = hydraulic power ÷ efficiency.

Formula and example

P hydraulic = ρ × 9.80665 × Q × H

For water at 1,000 kg/m³, 50 m³/h and 30 m head, hydraulic power is about 4.086 kW. At 70% overall efficiency, estimated input is about 5.837 kW.

Flow is converted from m³/h to m³/s.
Total head must already include the static and dynamic head basis appropriate to the system.
Efficiency is an entered overall planning assumption, not a motor-selection recommendation.

Last updated: 2026-09-16

Hydraulic power is the ideal rate of energy transferred to the fluid: density × gravity × volumetric flow × head.

Overall efficiency below 100% means the driver must supply more power than reaches the fluid.