Pump NPSH Available Calculator
NPSH available is the suction-side head the installation provides. It must exceed the pump curve NPSHr with enough margin for the service.
pump npsh available calculator npsha calculator net positive suction head
NPSHa formula
NPSHa = P_abs / (rho * g) + H_s - P_v / (rho * g) - h_f
Inputs that matter
- Absolute suction pressure: use absolute pressure, not unconverted gauge pressure.
- Static suction head: positive for flooded suction, negative for suction lift.
- Suction loss: include pipe, fittings, strainers, valves and entrance losses.
Margin check
Compare NPSHa to manufacturer NPSHr at the same flow. The calculator reports both margin and ratio.
Related pages
- Pipe pressure drop calculator - Darcy-Weisbach loss, head and velocity from flow and pipe ID.
- Pipe size by flow velocity - pick a first-pass pipe ID from flow and target velocity.
- Pump flow and HP calculator - pump displacement, pressure, flow, kW and horsepower.
- Pump NPSH calculator - available suction head and NPSH margin.