NPSHA Pump Calculator

This net positive suction head available (NPSHA) calculator provides the amount of available head for a pump. This head measurement is also referred to as the liquid pressure at the pump suction. Every pump requires a certain amount of net positive suction head, which is referred to as NPSHr. When NPSHa> NPSHr, the pump will have adequate back pressure to operate effectively.

NPSHA pump calculator

When NPSHa<NPSHr, serious operating conditions can occur. This may include but is not limited to: cavitation, inefficiencies, and vaporization of the fluid.

Calculation of NPSHa can be represented as:

NPSHa = atmospheric head + static head – vapor pressure – frictional piping losses

Vapor pressure losses increase with temperature. For the purposes of this calculator, vapor pressure losses are considered negligible as typical ambient operating conditions are assumed.

Calculation of friction losses is performed via the Hazen-Williams equation and thus is suitable for water only. In most scenarios, frictional piping losses are inconsequential.

Atmospheric Head
Static Head
Pipe Loss

* Height from pump shaft to top of fluid level being pumped