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BHP = Q × P / (1714 × n)


BHP = Brake Horsepower in Horsepower
Q = Flow Rate in gallons per minute
P = Pressure in pounds per square inch
n = Efficiency expressed as a decimal value*

*Many positive displacement pumps are assumed to operate at 90% efficiency. A value of 0.9 is often used for this calculation. For more accuracy, refer to your pump manufacturer’s pump test sheets.

Brake Horsepower [HP] = Flow Rate [GPM] × Pressure [PSI] / (1714 × Efficiency)


Flow Rate = 100 GPM
Operating Pressure = 500 PSI
Efficiency = 93%

100 [GPM] × 500 [PSI] / (1714 × 0.930) = 31.37 HP

The calculation above is only for single acting plunger and piston pumps. In a double acting plunger pump, the flow rate should be multiplied by 2. In a double acting piston pump, a modified piston diameter should be used where DP = 2 × DPiston – DRod


DPiston = Diameter of the Piston in inches
DRod = Diameter of the Drive Rod connecting to the piston

These calculations and the information provided on this page is for reference only. Power Zone Equipment is not responsible for errors or incorrect caclulations when applied to real life projects. Please use this information with care. For engineering assistance and design of equipment systems, please contact Power Zone Equipment.

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