Pump Efficiency Calculator
Calculate pump efficiency from flow rate, total head, and shaft power.
How it works
- 1Enter the pump’s flow rate, total head, and shaft (input) power.
- 2The calculator computes hydraulic power P = ρ·g·Q·H, then divides by shaft power.
- 3Read the efficiency percentage and a Good/Fair/Low rating.
Use cases
- Verifying a new pump runs within its design efficiency band.
- Comparing candidate pumps to minimise energy costs.
- Diagnosing worn impellers or cavitation by tracking efficiency over time.
Frequently asked questions
What is the pump efficiency formula?
η = hydraulic power ÷ shaft power, where hydraulic power = ρ·g·Q·H. For Q = 10 L/s and H = 20 m, hydraulic power ≈ 1962 W; with a 3 kW motor, η ≈ 65%.
What is a good pump efficiency?
Well-designed centrifugal pumps run at 70–85% at their best efficiency point. Below 50% usually means an oversized pump, wear, or operation far from the BEP.
Why does it show — when shaft power is zero?
Dividing by zero is undefined, so no efficiency can be computed. Enter the actual motor or measured shaft power.
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