Pump Horsepower Calculator

Calculate pump horsepower from flow rate, total dynamic head, and pump efficiency. Estimate hydraulic horsepower, brake horsepower, motor horsepower, watts, kilowatts, flow capacity, and horsepower margin for water pumps, booster pumps, well pumps, transfer pumps, irrigation pumps, and sump pumps.

Calculate Pump Horsepower

Pump HP = GPM × Total Dynamic Head ÷ 3960 ÷ Pump Efficiency.
Your result will appear here.

How the pump horsepower calculator works

Pump horsepower:
The calculator estimates brake horsepower from flow rate, total dynamic head, and pump efficiency.

Hydraulic horsepower:
The calculator estimates the useful water horsepower before pump losses.

Flow from horsepower:
The calculator estimates flow capacity from available horsepower, head, and efficiency.

Capacity check:
The calculator compares available motor horsepower against estimated horsepower need.

Why use a pump horsepower calculator?

A pump horsepower calculator helps estimate the motor size needed to move water at a required flow and head.

It can help compare flow rate, head, hydraulic horsepower, brake horsepower, motor horsepower, watts, kilowatts, and capacity margin.

What your result means

Your result shows estimated hydraulic horsepower, brake horsepower, and suggested motor horsepower. This is a planning estimate only. Final pump and motor selection should be checked against the manufacturer pump curve, motor service factor, total dynamic head, suction conditions, voltage, phase, and actual system layout.

Pump horsepower formulas

Frequently asked questions

How do you calculate pump horsepower?

Multiply flow in GPM by total dynamic head in feet, divide by 3960, then divide by pump efficiency.

What is hydraulic horsepower?

Hydraulic horsepower, also called water horsepower, is the useful power delivered to the water before accounting for pump efficiency losses.

What is brake horsepower?

Brake horsepower is the horsepower required at the pump shaft after accounting for pump efficiency.

Is this pump horsepower calculator exact?

No. This calculator gives a planning estimate. Final pump and motor sizing should be checked with the actual pump curve and manufacturer data.