Pump Calculator

What is Pump Horsepower?

Pump horsepower calculations are essential for selecting the right motor for a pump system. Water horsepower (WHP) is the theoretical minimum power needed, while brake horsepower (BHP) accounts for real-world efficiency losses in the pump.

Pump Formulas

The calculator uses standard pump equations for water in US units:

• Water Horsepower: WHP = Q × H / 3960 — theoretical hydraulic power
• Brake Horsepower: BHP = Q × H / (3960 × η) — actual shaft power required
• Pump Efficiency: η = WHP / BHP — ratio of output to input power

The constant 3960 converts gpm and feet of head to horsepower for water at standard conditions.

How to Use the Calculator

Select the variable you want to solve for:

• Water Horsepower: Enter flow rate in gpm and total dynamic head in feet
• Brake Horsepower: Enter flow rate, head, and pump efficiency percentage
• Pump Efficiency: Enter known WHP and BHP values

Applications

Pump calculations are critical for:

• Municipal water supply and distribution systems
• Irrigation system design
• Building services and high-rise water supply
• Industrial process pumping
• Fire protection system design

Also check: Pipe Flow Calculator, Pipe Hydrostatic Calculator, Pressure Calculator, Force Calculator, Power Calculator, and Work Calculator.