Hydroelectric Power Calculator

Enter your head (water fall height), flow rate, turbine efficiency, and turbine type to calculate hydroelectric power output in kilowatts. Choose between dam, run-of-river, or tidal turbine configurations. Results include power output (kW), annual energy generation (kWh), and estimated annual revenue based on your electricity rate. Also try the Solar Panel Wattage Calculator.

Turbine Type *

Select the type of hydroelectric installation to use the appropriate power formula.

m

The vertical height difference from the water surface to the turbine. Higher head means more power.

m³/s

Volume of water passing through the turbine per second. For dam and run-of-river types.

m/s

Water current speed for tidal turbines. Used instead of head for tidal power calculation.

m

Radius of the tidal turbine rotor. Used to compute the swept cross-sectional area.

%

Overall system efficiency including turbine and generator losses. Typical values: 70–90%.

$/kWh

Your local electricity price per kWh. Used to estimate annual revenue. US average is ~$0.13/kWh.

hrs/year

Hours the turbine operates per year. Max is 8,760 (365 days × 24 hrs). Tidal and run-of-river typically operate 6,000–8,000 hrs.

Results

Power Output

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Annual Energy Generation

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Estimated Annual Revenue

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Power Output (MW)

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Frequently Asked Questions

What is 'head' in hydroelectric power?

Head refers to the vertical height difference between the water surface and the turbine inlet. It is a measure of the water's potential energy. A higher head means more pressure and more energy available to drive the turbine. Common units include meters, feet, or PSI. See also our Solar Carport Calculator.

What formula is used to calculate hydroelectric power?

For dam and run-of-river turbines the formula is P = η × ρ × g × h × Q, where η is efficiency, ρ is water density (1000 kg/m³), g is gravity (9.81 m/s²), h is head in meters, and Q is flow rate in m³/s. For tidal turbines, P = 0.5 × η × ρ × A × v³ is used, where A is the rotor sweep area and v is water velocity.

What is a typical turbine efficiency?

Modern hydro turbines typically operate at 70–92% efficiency depending on design and operating conditions. A combined system efficiency (turbine + generator + transmission) of around 85% is a reasonable default for estimation purposes.

What are the three types of hydroelectric turbines?

The three main types are: (1) Dam turbines, which exploit the large head created by a reservoir behind a dam; (2) Run-of-river turbines, which divert part of a river's natural flow without a large reservoir; and (3) Tidal turbines, which harness the kinetic energy of tidal currents in the ocean rather than relying on head. You might also find our Renewable Energy Certificate (REC) Calculator useful.

What flow rate do I need for meaningful power generation?

It depends heavily on your available head. A high-head site (>20 m) can generate useful power with relatively modest flow — even 0.5 m³/s can produce tens of kilowatts. A low-head site (<10 m) requires significantly higher flow rates to generate comparable power. Doubling the flow doubles the power output.

How do I estimate my annual revenue from a hydro turbine?

Multiply your power output (kW) by your annual operational hours to get kWh generated per year. Then multiply by your local electricity rate ($/kWh). For example, a 50 kW turbine running 8,000 hours at $0.13/kWh would generate $52,000 per year before expenses.

Can I use a motor-driven pump to power a hydro turbine?

Almost always no. The turbine introduces flow restriction that makes the pump consume far more electricity than the turbine can generate. Hydro generation requires a natural head and flow source — a stream, river, dam, or tidal channel — to produce a net energy gain.

What is the difference between low-head and high-head hydro sites?

A low-head site has a vertical drop below 10 meters and requires high flow rates to generate meaningful power. A high-head site has a drop above 20 meters and can work with lower flow rates since gravity provides a stronger energy boost. High-head sites are generally more efficient and easier to harness with smaller equipment.