Wind Power Output Calculator
Speed unit
For the annual estimate; from a wind map at hub height
The generator's maximum output
Modern turbines peak around 40–48%; the Betz limit is 59.3%
1.225 at sea level, 15 °C; about 10% less at 1,000 m
Output at 8 m/s
1.49 MW
The wind passing through the 11,310 m² rotor carries 3.55 MW; the turbine captures 42% of it.
Rated output is reached at about 10.7 m/s. Power rises with the cube of wind speed: twice the wind, eight times the power.
Power curve and annual energy
Wind speed (m/s) across, kW up; the vertical line is the site mean.
- Energy a year
- 13,124 MWh
- Capacity factor
- 41.6%
- U.S. homes powered
- ≈ 1,215
Assumes wind speeds follow a Rayleigh distribution around the mean and a constant Cp up to rated power. Real power curves, wake losses and downtime usually cut output by 10–20%; onshore wind farms average 30–40% capacity factors. A U.S. home uses about 10,800 kWh a year.
Estimate a wind turbine's power output at any wind speed from its rotor size, power coefficient and rated power, its power curve between cut-in and cut-out speeds, and its annual energy and capacity factor at a site's mean wind speed.
Formula
Worked Example
The 11,310 m² rotor sees ½ × 1.225 × 11,310 × 8³ = 3.55 MW of wind power and captures 42% of it. Averaged over a Rayleigh spread of wind speeds around 7.5 m/s, it produces 13,124 MWh a year, enough for about 1,200 U.S. homes.
Frequently Asked Questions
Why does wind power depend on the cube of wind speed?
The kinetic energy of each kilogram of air rises with the square of its speed, and faster wind also pushes more kilograms through the rotor each second. Together that is v³: doubling the wind speed gives eight times the power, which is why site selection matters so much.
What is the Betz limit?
The theoretical maximum share of the wind's energy that any turbine can capture, 16/27 or 59.3%. Slowing the air completely would stop it flowing through the rotor, so some energy must pass through. Modern turbines reach power coefficients of about 45–50% at their best speed.
What is a typical capacity factor for wind?
Onshore wind farms in the U.S. average roughly 33–35% and the best new projects exceed 40%; offshore turbines often reach 40–50%. Capacity factor is the actual output over a year divided by what the turbine would make running at rated power all the time.