The required power by a fluid pump depends on a lot of parameters, like as:
Between the required parameters, the most difficult to estimate are the efficiency, they depends on the sequent factors:
Using this app, selecting correctly the kind of the pump, you obtain results that are sufficiently trustworthy, useful to estimate the absorbed current, consumed energy or the cost of the plant.
Selection of the kind of fluid
Density of fluid at 20 °C
Kind of pump
Required flow rate .. Q
Required fluid pressure .. H
Absorbed power .. P
Since the real efficiency values are not the same for every manufacturers and for every dimensions of the same kind of pump, here there are averaged values.
Low quality pump, with impeller and snail with too large construction tolerances or bad built could have efficiency also really smaller respect as given by the app.