NPSH Calculator

NPSH Calculator helps pump engineers, designers and operators quickly estimate suction line head losses and Net Positive Suction Head (NPSH) available.

Start on the Home screen by entering the pipe data used for head loss calculations: length, flow, internal diameter, pipe material and Hazen–Williams roughness C. Add local losses with the intuitive Fittings screen, where you can add or remove common fittings such as elbows, valves, contractions and foot valves, and see the total fitting coefficient used in the calculation.

On the NPSH screen, enter water temperature, site altitude, suction static head and the safety margin you want to apply. The app then calculates:

• Flow velocity in the suction pipe • Friction loss in the pipe • Minor losses due to fittings • Total suction head loss • Atmospheric head, vapor pressure head and applied safety margin • NPSH available at the pump suction

Results are shown in a clear, scrollable summary that separates input values, head loss results, NPSH inputs, NPSH available and the list of fittings used in the calculation. Explanatory tooltips and on-screen NPSH guidance help students and junior engineers understand where each term comes from and how it affects pump performance.

You can switch between US and SI units at any time (ft / gpm / in / °F or m / L/s / mm / °C), and all inputs and results are updated to the selected unit system for consistent, error-free work.

Use NPSH Calculator as a fast design and troubleshooting aid when sizing suction lines, reviewing pump selections or checking whether NPSH available comfortably exceeds the NPSH required by the pump manufacturer.

Note: This app is intended for preliminary calculations and educational use. Always confirm final designs and pump selections with a qualified engineer and the pump manufacturer.