Wind Turbine Calculator
20% more wind is 73% more energy.
Work out Wind Turbine. 20% more wind is 73% more energy. Shows the working, not just the answer.
Power at this wind speed
9.85 kW
78.5 m² swept · 67% of the Betz limit
Power goes with the cube of wind speed. A site with 20% more wind yields 73% more energy, which is why siting dominates every other decision — and why a difference in a wind survey that looks trivial is not. Betz's limit caps any turbine at 59.3% of the power in the wind, because extracting all of it would mean stopping the air completely and nothing could then flow through. Good large turbines reach 45 to 50%; small ones rarely pass 35%. Capacity factor is what turns a rating into energy. A 10 kW turbine at 30% makes the same annual energy as a 3 kW one running flat out, and the rated figure on a datasheet says almost nothing about output on its own.
How the Wind Turbine Calculator works
Power and annual energy from rotor diameter and wind speed, with the Betz limit shown alongside so you can see how much of the theoretical ceiling a real turbine reaches.
Also known as: how much power from a wind turbine · betz limit explained · wind turbine kwh per year · are small wind turbines worth it
Frequently asked questions
How is wind turbine power calculated?
½ × air density × swept area × wind speed cubed × power coefficient. The cube on speed and the square on diameter are what make siting and rotor size dominate everything else.
What is the Betz limit?
59.3% — the maximum share of the wind's power any turbine can extract. Taking all of it would mean stopping the air completely, and then nothing could flow through the rotor at all.
Why does a small increase in wind speed matter so much?
Because power goes with the cube. A site with 20% more wind yields 73% more energy, which is why a difference in a wind survey that looks trivial is not.
What is a capacity factor?
Annual energy as a share of what the turbine would make running at rated power all year. Onshore wind typically reaches 25 to 35%; offshore often 40 to 50%.
Are small wind turbines worth it?
Rarely, in built-up areas. Wind near buildings is turbulent and slow, and the cube law punishes that severely — the same turbine on an exposed mast can make several times the energy.
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