Power rises with the cube of wind speed, so doubling the wind gives eight times the power. The Betz limit caps efficiency at 59.3%.
How to use the Wind Turbine Power Calculator
- Rotor diameter
- Wind speed
- Air density
- Power coefficient (Cp)
- Capacity factor
Results update as you type, and every field accepts the units shown in its menu.
How it works
The swept area of the rotor and the cube of wind speed give the wind’s power; the power coefficient gives the share captured.
Inputs explained
| Field | What to enter |
|---|---|
| Rotor diameter | Units: m, cm, mm, km, in, ft … |
| Wind speed | Units: m/s, km/h, mph, ft/s, knots |
| Air density | In kg/m³ |
| Power coefficient (Cp) | A number |
| Capacity factor | In % |
What each result means
- Power output = 0.5×[Air density]×pi×([Rotor diameter]÷2)^2×[Wind speed]^3×[Power coefficient (Cp)]
- Energy per year (with capacity factor) = [Power output]×8760×[Capacity factor]÷100÷1000
Example values
How the main result changes when Rotor diameter changes and everything else stays at the example values above:
| Rotor diameter (m) | Power output (kW) |
|---|---|
| 5 | 1.44 |
| 7.5 | 3.25 |
| 10 | 5.78 |
| 12.5 | 9.02 |
| 15 | 12.99 |
| 20 | 23.1 |
Formula
P = ½ ρ A v³ CpWorked example
Inputs — Rotor diameter: 10 m; Wind speed: 7 m/s; Air density: 1.225 kg/m³; Power coefficient (Cp): 0.35; Capacity factor: 30 %.
Results — Power output = 5.78 kW; Energy per year (with capacity factor) = 15,177 kWh.
Frequently asked questions
What is the Betz limit?
No turbine can capture more than 16/27 (59.3%) of the wind’s kinetic energy.
What is capacity factor?
Actual yearly output as a share of the maximum possible; typically 25–45% for wind.
What formula does the Wind Turbine Power Calculator use?
P = ½ ρ A v³ Cp.