GPM to HP Calculator - Water Horsepower Calculator

Flow (gal/min):

Head (ft):

Specific Gravity:

Water Horsepower (hp):

What is Water Horsepower?

Water Horsepower (whp) is a measure of the energy imparted to water by a pump, as defined by the affinity laws. It depends on the pump's speed and impeller diameter.

It represents the theoretical power required to move a given flow of water against a specific head, adjusted by the fluid's specific gravity.

whp is widely used in pump design and selection to evaluate the efficiency and performance of pumping systems.

How to Calculate Water Horsepower

To calculate the Water Horsepower (whp), use the formula:

whp = \(\frac{Q \cdot h \cdot s}{3960}\)

Where:

Q = Flow, in gallons per minute (gal/min)
h = Head, in feet (ft)
s = Specific gravity

Use the form above to input the values, and the calculator will provide the whp.