Wind Turbine Power Calculator — Output & Annual Energy
Estimate how much electricity a wind turbine can generate. Enter the rotor radius, wind speed, power coefficient and capacity factor to get the power output in kW and expected annual energy in kWh.
m
m/s
%
Mechanical power extracted from the wind at the entered speed
- 1
Rotor sweep area: π × R²
π × 50² m = 7,854 m² - 2
Wind power through disk: ½ρAV³
0.5 × 1.225 × 7,854 × 10³ = 4,810.6 kWTotal kinetic energy flux through the rotor disk (ρ = 1.225 kg/m³). - 3
Extracted power: Cp × wind power
0.4 × 4,810.6 kW = 1,924.2
How does this calculator work?
Wind turbine power P = ½ × Cp × 1.225 × πr² × V³. The Betz limit caps Cp at 0.593; modern turbines reach 0.40–0.48. Annual output = P × 8 760 h × capacity factor. Doubling rotor radius quadruples output; doubling wind speed multiplies output by eight.
Formula
How this is calculated
A wind turbine extracts kinetic energy from the air passing through its rotor disk. The total power available in the wind is P_wind = ½ρAV³, where ρ is air density (1.225 kg/m³ at sea level and 15 °C), A = πr² is the rotor sweep area, and V is wind speed. Because power scales with the CUBE of wind speed, small increases in average wind speed substantially raise output.
The Betz limit, derived from conservation of momentum, sets a theoretical maximum efficiency of 59.3 % (Cp = 0.593) — no actuator-disk machine can capture more. Modern utility turbines achieve Cp ≈ 0.40–0.48 at their optimal tip-speed ratio. The extracted mechanical power is then reduced further by drivetrain and generator losses before becoming electrical output; those losses are not modelled here.
Annual energy production is estimated by multiplying the rated power by 8 760 hours and the capacity factor. The capacity factor (typically 25–40 % for onshore sites) accounts for wind variability, maintenance downtime and times when the turbine operates below its rated speed. The power curve chart shows the three operating regions: below cut-in speed (3 m/s) the turbine is idle; between cut-in and rated speed power follows the V³ law; above rated speed the pitch-control system limits output to the rated value until the cut-out speed (25 m/s), where the turbine shuts down for safety.
Frequently asked questions
The Betz limit (59.3 %) is the theoretical maximum fraction of the wind's kinetic energy that any rotor can extract, derived from conservation of mass and momentum. Real turbines reach 40–48 % at the best wind speed due to blade losses, tip effects and drivetrain inefficiency.
Power scales with the cube of wind speed (P ∝ V³). A 10 % increase in wind speed raises power by 33 %; doubling wind speed multiplies power by 8. This is why siting turbines at high-wind locations and maximising hub height — where wind speed is higher — has such a large impact on output.
Onshore wind turbines typically achieve 25–40 % capacity factors depending on the site wind resource and turbine design. Offshore turbines reach 40–55 % due to stronger, steadier winds. A higher capacity factor means more annual energy for the same rated power.
Also known as
TG we-Calculate Editorial Team. (2026). Wind Turbine Power Calculator — Output & Annual Energy [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/wind-turbine-calculator
TG we-Calculate Editorial Team. "Wind Turbine Power Calculator — Output & Annual Energy." TG we-Calculate. 2026. https://we-calculate.com/calculator/wind-turbine-calculator.
TG we-Calculate Editorial Team, "Wind Turbine Power Calculator — Output & Annual Energy," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/wind-turbine-calculator
@misc{wecalculate_wind_turbine_calculator, title = {Wind Turbine Power Calculator — Output & Annual Energy}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/wind-turbine-calculator}}, year = {2026}, note = {TG we-Calculate} }
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