Skip to content
ENExplore Calculators

Wind Speed Conversion

Free Wind Speed Conversion calculator with clear step-by-step results.

About Wind Speed Conversion

Converts between the four units wind is quoted in and extrapolates to a different height using the logarithmic wind profile, since wind speed rises with height above ground at a rate governed by surface roughness. The Beaufort force gives a descriptive scale for the measured speed.

Formulas

Log wind profile

v(z2) = v(z1) x ln(z2 / z0) / ln(z1 / z0)

Beaufort force

Force = round((speed m/s / 0.836)^(2/3))

Worked example

With the default values below, Wind Speed Conversion returns Wind speed at the target height of 19.156. Change any input above and every figure here is recalculated in your browser.

Inputs used

Wind speedminimum 0
15
Unit enteredone of Metres per second, Kilometres per hour, Miles per hour, Knots
Metres per second
Measurement heightminimum 0.5 m
10 m
Height to extrapolate tominimum 0.5 m
50 m
Surface roughness lengthaccepts 0–2 m
0.03 m

Results

Wind speed at the target height
19.156 m/s
Measured speed
54.00 km/h
Measured speed
29.16 kn
Beaufort force
7

Step by step

  1. 1Values used
  2. 2Log wind profile
  3. 3Beaufort force
  4. 4Wind speed at the target height= 19.156 m/s
  5. 5Measured speed= 54.00 km/h
  6. 6Measured speed= 29.16 kn
  7. 7Beaufort force= 7

Assumptions and limits

  • The result is derived only from the 5 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 3 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

What roughness length should I use?

About 0.0002 m over open water, 0.03 over open farmland, 0.1-0.3 with hedges and scattered buildings, and 0.5-1.5 in suburbs and forest.

Why does height matter so much?

Wind shear is substantial - at 0.03 m roughness, speed at 50 m is roughly 25% higher than at 10 m, and wind power scales with the cube of speed.

Related Calculators

Wind Speed Conversion | Calcrivo