Beaufort wind scale calculator
Convert wind speed to the Beaufort force (0 to 12) and see what each level means.
The Beaufort scale rates wind from 0 (calm) to 12 (hurricane) by observable effects, widely used in sailing and weather.
How the calculation works
Created by Francis Beaufort in 1805, the scale ties wind-speed ranges to a force from 0 to 12 and the effect on sea and land (leaves rustling, branches breaking, tiles flying…). Here we use the km/h thresholds.
Examples
- Wind of 25 km/h: force 4 ("moderate breeze", raises dust and paper).
- Wind of 90 km/h: force 10 ("storm", trees uprooted).
Frequently asked questions
At what force is it a hurricane?
Force 12, when wind exceeds ~118 km/h. Above that the classic Beaufort scale ends.
What is the Beaufort scale used for today?
It is still used in sailing and marine forecasts, and to describe wind by its observable effects without an anemometer.
How does it differ from the hurricane scale?
Beaufort goes 0–12 and covers all winds; the Saffir-Simpson scale (categories 1–5) classifies only hurricanes, above 118 km/h.
At what speed does wind get dangerous?
At 50–74 km/h walking against it is hard; 75–102 km/h dislodges roof tiles and fells trees; above 103 km/h damage is widespread.
Is 100 km/h wind twice as strong as 50?
No, four times stronger. Wind pressure grows with the square of speed.
Sustained wind or gusts?
Gusts, when assessing risk. They can exceed the sustained average by 30–50% and cause most of the damage.
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See all →Updated on June 30, 2026 · by Rafael Rossi · Methodology & sources