Pump Sizing Calculator

Size a centrifugal pump by calculating hydraulic horsepower, brake horsepower, motor size, NPSH required, and annual energy cost.

Flow Rate

GPM

Total Dynamic Head

Fluid Density

lb/ft³

Pump Efficiency

Tab to move between fields

Brake Horsepower

1.68 HP

≈ 21 laptops

Motor Size

2 HP

≈ 25 laptops

Hydraulic Horsepower1.26 HP

NPSH Required (est.)7.5 ft

Annual Energy Cost$1,100.00

How to Use This Calculator

Enter the Flow Rate in GPM required at the design operating point.
Enter the Total Dynamic Head in ft — sum static lift, friction losses in piping, and any pressure differential required at the destination.
Set the Fluid Density in lb/ft³: water at 60°F = 62.4 lb/ft³; adjust for other fluids.
Set the Pump Efficiency %: small centrifugal pumps ≈ 50–70%, large centrifugal ≈ 75–90%.
Review Brake Horsepower and the recommended Motor Size in HP — the motor should be the next standard size above BHP.
Check the estimated NPSH Required in ft against the available NPSH at the pump suction to prevent cavitation.

How the result changes with Pump Efficiency

Flow Rate: Required volumetric flow rate in gallons per minute at the design operating point.
Total Dynamic Head: Total head the pump must deliver, including static lift, friction losses, and velocity head.
Fluid Density: Density of the fluid being pumped. Water at 60°F = 62.4 lb/ft³; light oil ≈ 55; brine ≈ 75.
Pump Efficiency: Expected pump efficiency at the design point. Small pumps ≈ 50-70%; large centrifugal ≈ 75-90%.

Identify Input Parameters
4 parameters
Flow Rate = 100, Total Dynamic Head = 50, Fluid Density = 62.4, Pump Efficiency = 75 = 4 input(s) provided
Calculate Brake Horsepower
Brake Horsepower
1.68 = 1.68
Calculate Motor Size
Motor Size
2 = 2
Calculate Hydraulic Horsepower
Hydraulic Horsepower
1.26 = 1.26
Calculate NPSH Required
NPSH Required
7.5 = 7.5