Pump Hydraulic Power Calculator

Size the power a pump needs from its flow rate, head and efficiency. Enter the flow, the total head (pressure rise expressed as a column of fluid), the pipe diameter to get the flow velocity, the fluid's specific gravity, and the pump efficiency, and the tool returns the hydraulic (water) power delivered to the fluid and the brake (shaft) power the motor must supply. The core relation is power = ρ·g·Q·H, divided by efficiency for the input shaft power (imperial uses the equivalent HP = Q·H·SG ÷ 3960). Useful for selecting pump motors, sizing drives, and checking line velocity. Pure arithmetic — a steady-state ideal-fluid relation; real systems add friction losses, viscosity, NPSH and cavitation limits, motor service factor, and a duty-point that shifts with the system curve, so size the motor with margin and consult the pump curve. Everything runs locally in your browser.