Enter the volumetric flow, density, pump head, and efficiency into the calculator to determine the pump shaft power.

Pump Shaft Power Formula

The following formula is used to calculate a pump shaft power.

SP = HP / n 
  • Where SP is the shaft power (kW)
  • HP is the hydraulic power (kW)
  • n is the efficiency

To calculate the shaft power, divide the hydraulic power by the efficiency.

The hydraulic power can further be calculated with this formula:

HP = q*p*g*h / (3.6*10^6)

  • Where q is the flow rate (m^3/h)
  • p is the density (kg/m^3)
  • g is the acceleration due to gravity 9.81m/s
  • h is the pump head (m)

What is a pump shaft power?


A pump shaft power is the amount of power delivered or provided by the shaft of a pump. It is dependent on the hydraulic power and the efficiency.

How to calculate pump shaft power?

Example Problem:

The following example outlines how to calculate a pump shaft power.

First, determine the flow rate. In this example, the pump flow rate is 400 m^3/hr.

Next, determine the density of the fluid being pumped. For this example, the density is 1,225 kg/m^3.

Next, determine the pump head. This pump has a pressure differential of 3 m.

Next, determine the efficiency. This pump has an efficiency of 70% = .70.

Finally, calculate the pump shaft power using the formula above:

SP = HP / n

SP = 400*1225*9.81*3 / (3.6*10^6) / .7

SP = 572.2 kW