How to use the pump power calculator
Find the hydraulic and shaft power needed by a pump to lift water at a given flow and head. Enter flow rate, head, pump efficiency in the fields above; the hydraulic power, shaft power required are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “pump size”, “pump power calculator”, “water pump kW”, “calculate pump power”, “find hydraulic power”.
Formula
Variables
- Q — Flow rate (m³/s)
- H — Head (m)
- eff — Pump efficiency (%)
Worked example
With flow rate = 0.01 m³/s, head = 20 m, pump efficiency = 70 %, the calculator gives hydraulic power ≈ 1.96133 kW; shaft power required ≈ 2.8019 kW.
Frequently asked questions
What is the pump power calculator used for?
Find the hydraulic and shaft power needed by a pump to lift water at a given flow and head. It helps with questions such as “pump size”, “pump power calculator”, “water pump kW”.
What is the formula for the pump power calculation?
Hydraulic power (kW) = GRAV × Q × H. Shaft power required (kW) = [Hydraulic power] / (eff / 100). Here Q is flow rate (m³/s), H is head (m), eff is pump efficiency (%).
What inputs do I need for the pump power calculator?
You need flow rate in m³/s, head in m, pump efficiency in %. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the pump power calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the pump power result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.