Wind Turbine Output Calculator
A wind turbine's instantaneous power output depends on how much wind energy passes through its rotor and how efficiently it converts that energy into electricity. This calculator takes your wind speed, rotor diameter, air density, and power coefficient (Cp) and reports the swept rotor area and the resulting turbine power output in kilowatts. Because output scales with both rotor swept area and the cube of wind speed, rotor size and wind resource together dominate a turbine's real-world performance. Pair the result with our Wind Power Density Calculator to see the available energy per swept area before turbine losses, and our Annual Energy Production Calculator to convert instantaneous output into total energy delivered over a year.
The wind speed at hub height. Power output scales with the cube of wind speed, so this input has the largest effect on the result.
Modern utility-scale onshore turbines commonly use 100-170m rotor diameters.
1.225 kg/m3 is standard sea-level air density at 15C. Air density decreases with altitude and increases at lower temperatures.
The theoretical maximum (Betz limit) is 0.593. Real-world turbines typically achieve 0.35-0.45 due to mechanical, electrical, and aerodynamic losses.
π × (rotor diameter (m) ÷ 2)^2
(0.5 × air density (kg/m3) × swept area (m2) × wind speed (m/s)^3 × Cp) ÷ 1,000
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
This calculates instantaneous power output at a single wind speed, not accounting for cut-in speed (below which turbines don't operate), rated speed (above which output is capped by the turbine's electrical/mechanical limits), or cut-out speed (above which turbines shut down for safety). For total energy production over time, see the Annual Energy Production Calculator.
How we calculate this →Turbine output scales with rotor swept area as well as the cube of wind speed -- which is why modern turbines keep getting bigger rotors, not just taller towers. A 100m rotor diameter turbine at 8 m/s produces roughly 985 kW, but a 150m rotor at the same wind speed would produce more than double that, since swept area scales with the square of rotor diameter. This is the physical reason next-generation turbines are trending toward ever-larger rotors.
How wind turbine output is calculated
This calculator estimates the instantaneous electrical power output of a wind turbine at a single wind speed, tying four inputs together: the wind speed, the rotor diameter, the air density, and the power coefficient (Cp). Two quantities tie the calculation together.
Swept Rotor Area (m2) = π × (Rotor Diameter (m) ÷ 2)^2. The swept area is the circular disk of air the rotor blades sweep through, and it sets how much wind the turbine can intercept. Because area scales with the square of rotor diameter, a modest increase in blade length captures a much larger area of wind -- which is why increasing rotor size has become one of the primary strategies for boosting turbine output. At the default 100m rotor diameter, that is π × (100 ÷ 2)^2 = π × 2,500 = 7,854 m2.
Turbine Power Output (kW) = (0.5 × Air Density (kg/m3) × Swept Rotor Area (m2) × Wind Speed (m/s)^3 × Power Coefficient (Cp)) ÷ 1,000. The first three terms (0.5 × air density × swept area × wind speed cubed) give the total kinetic power available in the wind passing through the rotor -- the same cubic relationship that drives wind power density. The power coefficient (Cp) then captures what fraction of that available power the turbine actually converts to electricity, since no turbine can extract all of the wind's energy. Dividing by 1,000 converts watts to kilowatts. At the defaults (8 m/s, 100m rotor, 1.225 kg/m3, Cp 0.40), that is (0.5 × 1.225 × 7,854 × 8^3 × 0.40) ÷ 1,000 = (0.5 × 1.225 × 7,854 × 512 × 0.40) ÷ 1,000 = 985,305 ÷ 1,000 = 985.3 kW.
Two notes on the model. First, the power coefficient (Cp) is bounded by the Betz limit, a fundamental physics constraint that caps the fraction of wind energy any turbine can extract at 59.3% (0.593). Real-world turbines typically achieve 0.35-0.45 due to additional mechanical, electrical, and aerodynamic losses beyond the Betz limit. Second, this calculator reports instantaneous theoretical output at a single specified wind speed -- it does not model a turbine's full power curve, which includes a cut-in speed (below which the turbine doesn't generate power), a rated speed (above which output is capped by the turbine's electrical and mechanical limits), and a cut-out speed (above which the turbine shuts down for safety). For total energy delivered over time rather than instantaneous power, use the Annual Energy Production Calculator. Data sources: wind turbine power output formula from IEC 61400 wind turbine design standards and wind physics; Betz limit and power coefficient data from aerodynamic theory and turbine design literature; swept rotor area calculation from geometric principles; real-world Cp values from utility-scale and onshore wind turbine manufacturer specifications and field performance data; turbine cut-in/rated/cut-out speeds from power curve analysis and wind turbine design standards. Verification: with defaults (8 m/s, 100m rotor, 1.225 kg/m3, Cp 0.40), Swept Rotor Area = 7,854 m2, Turbine Power Output = 985 kW.