Wind Turbine Power Output
Calculate wind turbine power output in kW and estimated annual generation based on rotor diameter, wind speed, and power coefficient.
Results
What is it?
Wind turbine power output follows the equation P = 0.5 x rho x A x Cp x v^3, where rho is air density (kg/m3), A is the rotor swept area (m2), Cp is the power coefficient (efficiency), and v is wind speed (m/s). The Betz limit (Cp = 0.593) is the theoretical maximum efficiency — no turbine can extract more than 59.3% of the wind's kinetic energy.
How to use
1. Enter the rotor diameter in meters. 2. Enter the design wind speed in m/s (use your site mean wind speed for annual estimates). 3. Enter the power coefficient (Cp) — modern turbines achieve 0.35-0.45. 4. Adjust air density for your altitude if needed (lower at altitude). 5. Compare your Cp to the Betz limit to see how efficient your turbine is.
Example scenario
A small 10-meter diameter turbine with Cp = 0.35 at 8 m/s wind speed. Swept area = pi x 25 = 78.5 m2. Power = 0.5 x 1.225 x 78.5 x 0.35 x 512 = 8,640 W = 8.64 kW. At 35% capacity factor, annual generation = 8.64 x 8,760 x 0.35 = 26,500 kWh/yr.
Pro tip
Wind power scales with the CUBE of wind speed — doubling wind speed increases power 8-fold. This means site selection is critical: a site with average 8 m/s wind generates 8x more power than a 4 m/s site for the same turbine. Even a 1 m/s improvement in wind speed (~12.5%) increases power by nearly 42% (1.125^3 = 1.42).