Formula
Brake HP = Water HP ÷ Pump Efficiency
Water HP is the theoretical power required to move the fluid. Brake HP is the actual mechanical power the motor must supply to the pump shaft, accounting for the pump's inefficiencies.
Worked Example
This calculator provides estimates based on standard mathematical formulas. Real-world results will vary based on mechanical condition, environmental factors, and other variables.
Frequently Asked Questions
TDH is the total equivalent height that a fluid is to be pumped, taking into account friction losses in the pipe.
Specific gravity is the ratio of a fluid's density to water. Water is 1.0. Heavy mud might be 1.5, meaning it requires 50% more power to pump.
Hydraulic horsepower is the useful power delivered to the fluid; brake horsepower is what the motor must supply, found by dividing hydraulic HP by pump efficiency.
Most centrifugal pumps run 50–85% efficient. If you don't know the exact figure, 70% is a reasonable starting estimate for sizing.
Higher head (the height or pressure the pump must overcome) increases the horsepower required proportionally, as does higher flow rate.