How to read a pump curve

The performance curve is a pump's "identity card": it relates flow (how much liquid it moves) to head (how much pressure it generates). Reading it is the safest way to choose the right pump.

The axes: flow and head

The horizontal axis (X) shows flow in m³/h; the vertical axis (Y) shows head in metres. The curve slopes down left to right: the more liquid you move, the less pressure remains. At zero flow head is maximum; at zero head flow is maximum.

The duty point

The duty point is where the pump curve meets the system curve (pipe resistance). A well-chosen pump has its duty point in the central third of the curve, where efficiency peaks.

Efficiency and NPSH

Most charts also show the efficiency (η) curve and the NPSH required: the first shows how much energy becomes useful work, the second the minimum suction pressure to avoid cavitation.

Try it live

In our pump selector every model shows an interactive curve: hover (or touch on mobile) to read flow and head at any point, with your duty point already highlighted.