Pump Power Calculator
Pumping 20 L/s against a total head of 30 m at 70 % efficiency takes 8.40857 kW at the shaft.
8.40857142857143 kW
Full answer, then cut to fewer decimals (not rounded):
- 8.40857142857143 kW
- 8.4085714285714 kW
- 8.408571428571 kW
- 8.40857142857 kW
- 8.4085714285 kW
- 8.408571428 kW
- 8.40857142 kW
- 8.4085714 kW
- 8.408571 kW
- 8.40857 kW
- 8.4085 kW
- 8.408 kW
- 8.40 kW
- 8.4 kW
- Water (hydraulic) power ρgQH
- 5.886 kW
- In horsepower
- 11.27608002 hp
- Specific speed N√Q / H^(3/4) (m³/s, m)
- 15.99712944
Step-by-step solution
- P_w = ρ g Q H = 1000 × 9.81 × 0.02 × 30 = 5886 W
- P_shaft = P_w / η = 5886 ÷ 0.7 = 8408.571429 W
Pump Power Formula
P = ρ g Q H / η
specific speed N_s = N√Q / H^(3/4) with Q in m³/s and H in m
Worked Example
20 L/s against a 30 m head at 70 % efficiency:
- P_w = ρ g Q H = 1000 × 9.81 × 0.02 × 30 = 5886 W
- P_shaft = P_w / η = 5886 ÷ 0.7 = 8408.571429 W
In horsepower: 11.27608002 hp · Specific speed N√Q / H^(3/4) (m³/s, m): 15.99712944
GATE tip
Select the motor 10–20 % above the shaft power, and size it on the duty point of the pump curve.
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Frequently asked questions
What does specific speed tell me?
The pump type: low N_s (about 10–35) radial centrifugal, medium mixed flow, high (above 160) axial flow.
What goes into a pump’s total head?
Static lift plus friction losses in the suction and delivery pipes plus the velocity head at the outlet.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Pump Power Calculator. Retrieved October 29, 2026, from https://scientificconverters.com/calculators/pump-power-calculator/
IEEE
Scientific Converters, "Pump Power Calculator," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/calculators/pump-power-calculator/