Wind Turbine Output Calculator
Estimate the power a wind turbine generates at a given wind speed.
Results update as you type.
How it works
Wind turbines convert the kinetic energy of moving air into electricity, and their output depends heavily on how fast the wind blows and how large the blades are. This wind turbine output calculator estimates the power a turbine generates from four inputs: blade radius, wind speed, efficiency, and air density. It returns the electrical power output in watts. The wind power equation reveals why wind speed matters so much: power rises with the cube of wind speed, so doubling the wind produces eight times the power. The swept area grows with the square of the blade radius, so longer blades capture proportionally more wind. Efficiency accounts for the Betz limit — the physical maximum of about 59 percent that no turbine can exceed — and real-world losses, with modern turbines reaching roughly 35 to 45 percent. Understanding these relationships helps you appreciate why wind farms favour tall turbines with huge blades on windy sites, and why a modest drop in average wind speed sharply reduces output. Students learning renewable physics, hobbyists sizing a small turbine, and anyone curious about wind energy use a wind turbine output calculator to see how design and conditions drive generation. The result is an instantaneous power figure at the wind speed you enter; because real wind varies constantly, average output over time depends on the full distribution of wind speeds at the site.
P = ½ × ρ × π × r² × v³ × efficiency%
A wind turbine extracts kinetic energy from moving air. The power available equals half the air density (ρ) times the swept area of the blades (π × r²) times the wind speed cubed (v³), because faster wind carries disproportionately more energy. Multiplying by an efficiency fraction accounts for the fact that no turbine captures all the wind's energy — the physical limit is about 59 percent, and real turbines reach roughly 35 to 45 percent — giving the realistic electrical power the turbine produces.
Source:U.S. Department of Energy wind power fundamentals
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter blade radius, wind speed, efficiency and air density.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Power output updates instantly as you type — no button to press.
Frequently asked questions
Why does power depend on wind speed cubed?
The kinetic energy of moving air rises with the square of its speed, and the rate at which that air passes through the blades also rises with speed, so the two effects combine to make power proportional to the cube of wind speed. This is why wind speed dominates output: doubling the wind gives eight times the power, and why turbine siting on consistently windy locations matters far more than almost any other factor.
What efficiency should I enter?
The theoretical maximum, called the Betz limit, is about 59 percent — no turbine can extract more than that fraction of the wind's energy. Real modern turbines achieve roughly 35 to 45 percent after aerodynamic, mechanical, and electrical losses, so 40 percent is a sensible default. Small or older turbines may be lower. Do not enter values near or above 59 percent, as they would exceed what physics permits and overstate the output.
What is air density and why does it matter?
Air density is the mass of air per cubic metre, about 1.225 kilograms at sea level and 15°C. Denser air carries more energy at the same speed, so it raises output. Density falls at high altitude and in hot weather, and rises in cold conditions, which is why turbines can produce slightly more on cold days. For most estimates the standard sea-level value works well unless your site is notably high or hot.
Is this the turbine's average output over time?
No, it is the instantaneous power at the exact wind speed you enter. Real wind constantly varies, and turbines only generate between a cut-in speed and a cut-out speed, reaching rated power in strong winds and shutting down in extreme gusts. Average real output, expressed as a capacity factor, is typically 25 to 45 percent of the turbine's rated maximum, so long-term generation depends on the full range of wind speeds at the site.
How does blade length affect output?
Output rises with the square of the blade radius because the swept area — the circle the blades trace — grows as radius squared. Doubling blade length quadruples the swept area and therefore the power captured, all else equal. This is why manufacturers keep building larger rotors: bigger blades harvest far more wind. It also explains why large utility turbines with blades tens of metres long vastly outproduce small residential units.