About the Wind Turbine Power Calculator
The power in moving air depends on the area the blades sweep and, strongly, on the wind speed. This calculator finds the power in the wind through the rotor, the output at the power coefficient you choose and the Betz limit, the highest share of that power any turbine can capture. Type rotor diameter, wind speed, Cp and air density and the wind turbine power appears at once, with a few related figures underneath, and you can copy the result with one tap. The sums run in your browser, so nothing you enter is uploaded.
Updated October 2026
How to use the Wind Turbine Power Calculator
- 1Enter rotor diameter, wind speed, Cp and air density.
- 2Pick the units or options from the menus if the wind turbine power tool offers them.
- 3Read the wind turbine power in the large result box.
- 4Look at the extra rows for related figures.
- 5Press Copy result to keep the answer.
When you need the wind turbine power
Home and farm owners use it to size small turbines, and students use it to learn why wind speed matters most.
Because the speed is cubed, wind of 10 m/s carries almost twice the power of 8 m/s. Doubling the rotor diameter makes the swept area four times larger.
How the wind turbine power is worked out
Power in the wind = ½ × air density × swept area × wind speed³. Output = that × Cp. The Betz limit is 16/27, or 59.3%, of the wind power. A 10 m rotor sweeps 78.5 m². In an 8 m/s wind with air density 1.225, the wind carries 24.6 kW. At Cp 0.35 the output is about 8.6 kW, and the Betz limit is 14.6 kW.
Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.
- Betz limit shown
- Swept area
- Adjustable air density
Mistakes to avoid with wind turbine power
Rated power is given at one wind speed; actual yearly energy depends on how often the wind blows. Cut-in and cut-out speeds also limit real output.
On phone and computer
On a phone, type into the boxes one after another and read the wind turbine power underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the wind turbine power move. The wind turbine power calculator works the same on both.
Checking your wind turbine power by hand
A good habit is to test the wind turbine power calculator with a case you already know. A 10 m rotor sweeps 78.5 m². In an 8 m/s wind with air density 1.225, the wind carries 24.6 kW. At Cp 0.35 the output is about 8.6 kW, and the Betz limit is 14.6 kW.
If your own figures give a surprising answer, repeat the working yourself: Power in the wind = ½ × air density × swept area × wind speed³. Output = that × Cp. The Betz limit is 16/27, or 59.3%, of the wind power. Small differences usually come from rounding, from mixing units, or from a typing slip in one of the inputs. Power depends on wind speed and blade size. Compare another fluid machine with the Pump Power Calculator, convert units with the Pressure Converter, and see the cost of energy with the Electricity Cost Calculator.
Features
- Wind speed is cubed
- Rated vs actual output
- Cut-in and cut-out speeds
- Clear messages when the wind turbine power inputs make no sense
- Copy the result with one tap
- Private: nothing is uploaded
Frequently asked questions
How do I calculate wind turbine power?
Power in the wind = ½ × air density × swept area × wind speed³. Output = that × Cp. The Betz limit is 16/27, or 59.3%, of the wind power. A 10 m rotor sweeps 78.5 m². In an 8 m/s wind with air density 1.225, the wind carries 24.6 kW. At Cp 0.35 the output is about 8.6 kW, and the Betz limit is 14.6 kW.
What is the formula for wind turbine power?
Power in the wind = ½ × air density × swept area × wind speed³. Output = that × Cp. The Betz limit is 16/27, or 59.3%, of the wind power. The wind turbine power calculator applies it exactly and rounds only the displayed answer to six significant figures.
What is the Betz limit?
The maximum fraction, 59.3%, of wind energy any turbine can capture.
What is a typical Cp?
Modern large turbines reach 0.4 to 0.5.
How does wind speed matter?
Power rises with the cube of wind speed.
Is this wind turbine power calculator free and private?
Yes. It is free, needs no account and runs in your browser, so the numbers you type are not uploaded or stored.