Pump Head Calculator

Calculate Total Dynamic Head (TDH), Net Positive Suction Head (NPSH), and hydraulic power

Pump Parameters

Enter system conditions for pump head calculation

Static Head
Positive = lift below pump, Negative = flooded suction
Elevation to discharge point
Friction Losses
System Pressure
Atmospheric = 14.7 psi
Fluid Properties
Water = 1.0, Light crude ~0.85
Typical centrifugal pump: 60-85%
NPSH Calculation (Optional)
At pumping temperature
From pump curve

Calculation Results

Enter parameters and click Calculate

Quick Tips

  • TDH = Static + Pressure + Friction heads
  • NPSHa must exceed NPSHr to avoid cavitation
  • Recommended NPSH margin: 3 ft or 15% above NPSHr
  • Higher viscosity fluids require power derating

Formula Reference

Total Dynamic Head (TDH)

TDH = Static Head + Pressure Head + Friction Head Static Head = Discharge Elevation - Suction Elevation Pressure Head = (Pd - Ps) x 2.31 / SG Friction Head = Suction Friction + Discharge Friction

Hydraulic Horsepower

HHP = (Q x TDH x SG) / 3960 Where: Q = Flow rate (GPM) TDH = Total Dynamic Head (ft) SG = Specific Gravity 3960 = Conversion constant

Brake Horsepower

BHP = HHP / Pump Efficiency Motor kW = BHP x 0.746

Net Positive Suction Head Available (NPSHa)

NPSHa = (Ps x 2.31 / SG) - Suction Lift - Friction Loss - (Pv x 2.31 / SG) Where: Ps = Absolute pressure at suction surface (psia) Pv = Vapor pressure of liquid at pumping temp (psia) SG = Specific Gravity 2.31 = Conversion factor (psi to ft of water)

NPSH Margin Recommendations

Per Hydraulic Institute standards:

  • Minimum: NPSHa > NPSHr + 3 ft
  • Preferred: NPSHa > 1.15 x NPSHr
  • For hydrocarbon service: NPSHa > 1.25 x NPSHr