Hydro Power Output Calculator

Work out hydro power output instantly with clear inputs, formula shown and shareable results.

About Hydro Power Output Calculator

Hydro power is P = rho g Q H, or 9.81 x flow in cubic metres per second x net head in metres, giving kilowatts. Net head is gross head less friction losses in the penstock. Turbine efficiency reaches 90-94% for a well-matched Francis or Kaplan machine, and generator efficiency 95-98%.

Formula

Hydro power

P (kW) = 9.81 x Q (m3/s) x H (m) x turbine efficiency x generator efficiency

Worked example

With the default values below, Hydro Power Output Calculator returns Electrical Power Output of 4.5770. Change any input above and every figure here is recalculated in your browser.

Inputs used

Flow Rateminimum 0 m3/s: 12 m3/s
Net Headminimum 0 m: 45 m
Turbine Efficiencyaccepts 1–100 %: 90 %
Generator Efficiencyaccepts 1–100 %: 96 %

Results

Electrical Power Output: 4.5770
Hydraulic Power Available: 5.2974
Overall Efficiency: 86.400%
Annual Energy At 50% Capacity Factor: 20,047.1

Step by step

1Values used
2Hydro power
3Electrical Power Output= 4.5770
4Hydraulic Power Available= 5.2974
5Overall Efficiency= 86.400
6Annual Energy At 50% Capacity Factor= 20,047.1

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Hydropower development requires water abstraction rights, environmental flow requirements and dam safety approvals. Confirm regulatory requirements before design.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Hydropower development requires water abstraction rights, environmental flow requirements and dam safety approvals. Confirm regulatory requirements before design.

Frequently Asked Questions

Which turbine suits which head?

Pelton for high head above 100 m with low flow, Francis for 20-300 m medium head, Kaplan and propeller for low head under 30 m with high flow. Cross-flow turbines suit small low-head sites.

Why does net head matter rather than gross?

Friction in the intake, penstock and draft tube consumes head that never reaches the runner. On long penstocks losses of 5-10% of gross head are common and must be designed against.