Environmental Science
Advanced

Wind Turbine Power

Power extracted from wind by a turbine.

Formula

P=12ρAv3CpP = \frac{1}{2}\rho A v^3 C_p

Variables

\rhoAir density
ASwept area
vWind speed
C_pPower coefficient

Example

Power scales with the cube of wind speed

How it works

This equation estimates how much mechanical/electrical power a wind turbine can extract from moving air. It comes from the kinetic energy carried by the wind passing through the rotor area each second: the mass flow rate through the swept disk is proportional to air density, area, and wind speed, while the energy per unit mass grows with v^2, giving an overall v^3 dependence. The factor C_p captures the real turbine’s efficiency, since no rotor can remove all of the wind’s energy and practical designs are limited by aerodynamics and the Betz limit.

When to use it

Use this formula when estimating turbine output from site conditions, comparing rotor sizes, or evaluating how changes in wind speed affect generation. It is also useful in renewable-energy studies, feasibility analyses, and turbine performance calculations.

Worked example, step by step

Given: ρ = 1.225 kg/m^3, A = 50 m^2, v = 8.0 m/s, C_p = 0.40 Step 1: Substitute into the formula P = 1/2 × ρ × A × v^3 × C_p Step 2: Compute the wind-speed term v^3 = 8.0^3 = 512 Step 3: Multiply the constants 1/2 × 1.225 × 50 × 0.40 = 12.25 Step 4: Multiply by v^3 P = 12.25 × 512 = 6272 W Final answer: P ≈ 6.27 kW

Common mistakes to avoid

  • using rotor diameter instead of swept area A
  • forgetting that wind speed is cubed, not squared
  • choosing an unrealistic Cp greater than the physical limit or not matching the turbine design

Did You Know?

Doubling wind speed gives eight times the power.

Share this formula

Reviewed & maintained by the FormulaWon editorial teamLast reviewed September 2026