Hydroelectric Power Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Hydropower depends on how much water is moving, how much usable head or kinetic energy it carries, and how efficiently a turbine converts that energy. This calculator exposes those pieces directly, letting you switch between a head-based dam model and kinetic-flow models for run-of-river or tidal scenarios.

What this calculator does

The Hydroelectric Power Calculator estimates discharge, electrical power, operating-period energy, and revenue. For a dam it uses hydraulic head; for run-of-river or tidal selections it uses the kinetic energy of moving water. Area and velocity determine flow rate, while water density, gravity, efficiency, operating days, and tariff complete the selected scenario.

How to use it

Choose the turbine scenario, enter the flow cross-sectional area and water velocity, then provide head for a dam case. Check water density, gravity, efficiency, operating days, and electricity tariff. Area × velocity should represent the water actually passing through the modeled turbine flow path—not the full river or reservoir unless all of that flow is captured.

How the calculation works

Discharge is Q = A × v. For a dam, power is P = ηρghQ. For run-of-river or tidal mode, the current calculator uses P = ½ηρQv². Power is converted to kW, then operating energy = kW × 24 × operating days. Revenue = operating energy × electricity tariff.

Example

Using the default dam scenario—150 m² area, 2 m/s velocity, 15 m head, water density 998 kg/m³, gravity 9.81 m/s², and 80% efficiency—gives Q = 300 m³/s. The resulting modeled power is about 35,245 kW before the calculator projects operating energy and tariff-based revenue.

How to interpret the result

Power responds strongly to the physical driver in each mode. In the dam case it scales linearly with head, discharge, and efficiency; in the kinetic-flow case velocity is especially influential because it appears in the moving-water energy term as well as discharge. Use the energy and revenue metrics only after checking whether the operating-day assumption is realistic.

Limitations and notes

Real projects require flow-duration curves, seasonal hydrology, turbine efficiency curves, intake and penstock losses, environmental flow requirements, generator losses, downtime, permitting, and grid constraints. A large theoretical water cross-section can make the estimate unrealistically high if the turbine cannot capture that flow. This is a first-pass physics and scenario calculator, not a project feasibility study.