Wind Speed At Hub Height Calculator

Work out wind speed at hub height instantly with clear inputs, formula shown and shareable results.

About Wind Speed At Hub Height Calculator

The power law extrapolates wind speed with height: v2 = v1 x (h2/h1)^alpha. The shear exponent is about 0.10-0.14 over water and smooth ground, 0.20 over open farmland and 0.25-0.40 over forest and built-up terrain. Because power varies with speed cubed, a 20% speed gain gives a 73% power gain.

Formulas

Power law wind shear

v2 = v1 x (h2 / h1)^alpha

Power scaling

Power ratio = (v2 / v1)^3

Worked example

With the default values below, Wind Speed At Hub Height Calculator returns Wind Speed At Hub Height of 10.6844. Change any input above and every figure here is recalculated in your browser.

Inputs used

Measured Wind Speedminimum 0 m/s: 6.5 m/s
Measurement Heightminimum 0.01 m: 10 m
Hub Heightminimum 0.01 m: 120 m
Wind Shear Exponentaccepts 0–0.6: 0.2

Results

Wind Speed At Hub Height: 10.6844
Speed Increase: 64.38%
Power Increase Ratio: 4.4413
Height Ratio: 12.000

Step by step

1Values used
2Power law wind shear
3Power scaling
4Wind Speed At Hub Height= 10.6844
5Speed Increase= 64.38
6Power Increase Ratio= 4.4413
7Height Ratio= 12.000

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why do turbines keep getting taller?

Because both speed and power rise with height. Going from 80 m to 120 m hub height at alpha = 0.2 adds about 8.5% speed and 28% energy, which usually outweighs the extra tower cost.

How is the shear exponent determined?

From simultaneous measurements at two or more heights on a met mast, or from lidar. It varies with time of day and stability, so annual and diurnal averages differ.