Pump Efficiency Calculator
Calculate the overall efficiency of a pump by comparing hydraulic power delivered to the fluid against the shaft (brake) power supplied to the pump.
Formulas Used
Hydraulic (Water) Power:
Phyd = ρ · g · Q · H
- ρ = fluid density (kg/m³)
- g = gravitational acceleration = 9.80665 m/s²
- Q = volumetric flow rate (m³/s)
- H = total head (m) — sum of static, velocity, and pressure head
Pump Efficiency:
η (%) = ( Phyd / Pshaft ) × 100
- Pshaft = brake power delivered to the pump shaft (W)
- η = overall pump efficiency (%)
Pressure-based head conversion:
H = ΔP / (ρ · g)
Assumptions & References
- Gravitational acceleration is taken as g = 9.80665 m/s² (standard gravity, ISO 80000-3).
- The calculated efficiency is the overall (total) pump efficiency, which combines hydraulic, volumetric, and mechanical sub-efficiencies into a single figure.
- Total head (H) must represent the net head rise across the pump (discharge head minus suction head), including static lift, friction losses, and velocity head differences.
- Shaft power is the brake power measured at the pump shaft coupling, not the motor input power. Motor efficiency losses are excluded.
- Fluid is assumed to be incompressible (valid for liquids; not applicable to gases or compressible fluids).
- Water density at 20 °C ≈ 998 kg/m³; the default 1000 kg/m³ is a standard engineering approximation.
- Typical centrifugal pump efficiencies range from 50 % (small/low-flow) to 90 % (large industrial).
- References: Hydraulic Institute Standards (ANSI/HI 1.3); Munson, Young & Okiishi, Fundamentals of Fluid Mechanics; ISO 9906 — Rotodynamic pumps: hydraulic performance acceptance tests.