Pump Power Calculator
Pump Power is evaluated from Flow Rate, Total Head and Pump Efficiency. The calculation reports Hydraulic Power, Shaft / Brake HP Required and Shaft Power.
Results
About the Pump Power Calculator
The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.
Formula basis:
WHP = Q(GPM) x H(ft) x SG / 3960
BHP = WHP / η
Motor HP = BHP / 0.90 (round up to next NEMA size)
SI: Power (kW) = ρ x g x Q x H / 1000 / η
For water: P(kW) = 9.81 x Q(m^3/s) x H(m) / η
Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.
Formula & How It Works
The calculation applies the following relations exactly as recorded in the metadata: WHP = Q(GPM) x H(ft) x SG / 3960 BHP = WHP / η Motor HP = BHP / 0.90 (round up to next NEMA size) SI: Power (kW) = ρ x g x Q x H / 1000 / η For water: P(kW) = 9.81 x Q(m^3/s) x H(m) / η Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.
Worked Examples
Example 1: Residential Pool Pump
Inputs
With Flow Rate = 75, Total Head = 45, Pump Efficiency = 72 and Fluid Specific Gravity = 1 as the stated inputs, the result is Hydraulic Power = 0.852 HP, Shaft / Brake HP Required = 1.184 HP and Shaft Power = 0.883 kW. Each value corresponds to the declared output fields.
Example 2: Municipal Booster Pump Station
Inputs
With Flow Rate = 2,000, Total Head = 120, Pump Efficiency = 80 and Fluid Specific Gravity = 1 as the stated inputs, the result is Hydraulic Power = 60.606 HP, Shaft / Brake HP Required = 75.758 HP and Shaft Power = 56.492 kW. Each value corresponds to the declared output fields.
Example 3: Agricultural Irrigation Pump — Lifting from Well
Inputs
With Flow Rate = 300, Total Head = 250, Pump Efficiency = 75 and Fluid Specific Gravity = 1 as the stated inputs, the result is Hydraulic Power = 18.939 HP, Shaft / Brake HP Required = 25.253 HP and Shaft Power = 18.831 kW. Each value corresponds to the declared output fields.
Example 4: Seawater Desalination Feed Pump
Inputs
With Flow Rate = 500, Total Head = 800, Pump Efficiency = 78 and Fluid Specific Gravity = 1.025 as the stated inputs, the result is Hydraulic Power = 103.535 HP, Shaft / Brake HP Required = 132.738 HP and Shaft Power = 98.982 kW. Each value corresponds to the declared output fields.
Common Use Cases
- Calculate horsepower needed to pump water to a certain height
- Find hydraulic power for a given flow rate and head
- Determine pump motor size for irrigation or industrial use