Beaufort Scale
Calculator
Results
- Beaufort force
- 6
- Wind speed (km/h)
- 43.2
- Wind speed (knots)
- 23.326133
Weather results
| Beaufort force | 6 |
| Wind speed (km/h) | 43.2 |
| Wind speed (knots) | 23.326133 |
formula-map diagram
- Beaufort force
- 6
- Wind speed (km/h)
- 43.2
- Wind speed (knots)
- 23.326133
Weather relationship
Formula
Beaufort force = band containing v (0 <0.5, 1 <1.5, 2 <3.3, 3 <5.4, 4 <7.9, 5 <10.7, 6 <13.8, 7 <17.1, 8 <20.7, 9 <24.4, 10 <28.4, 11 <32.6, 12 ≥32.6 m/s)= 6
Note
This is a simplified model: it applies the published standard formula to the numbers you entered and ignores local terrain, radiation, precipitation type and instrument error. Wind chill is the 2001 NWS/Environment Canada regression, valid at or below 10 °C with wind at or above 4.8 km/h; the heat index is the Rothfusz regression, reliable above about 27 °C; dew point uses the Magnus approximation (a = 17.27, b = 237.7 °C) over liquid water; wet bulb uses Stull's approximation at standard sea-level pressure; pressure and density altitude assume the International Standard Atmosphere and dry air. Do not use these results for aviation, structural or safety decisions without an official forecast or a qualified professional.
More in Weather and climate
See all →Frequently asked questions
What is the Beaufort scale actually measuring?+
The Beaufort scale is a system that translates wind speed into a numbered category (0 to 12) based on observable effects, originally on sea conditions and later extended to effects on land, like smoke drift, tree movement, or structural damage, rather than requiring a direct wind speed instrument reading.
How does this calculator convert a wind speed measurement into a Beaufort number?+
It matches the input wind speed against the defined speed range for each Beaufort category; each number from 0 (calm) to 12 (hurricane force) corresponds to a specific wind speed band, roughly increasing in a non-linear progression as the numbers rise.
Why was the Beaufort scale originally based on observed effects rather than instrument readings?+
It was developed in the early 19th century for sailors before reliable anemometers existed, so it needed to be usable just from what a ship's crew could see and feel, like how much sail a ship could carry or how the sea surface looked, rather than requiring a wind speed instrument.
Is the Beaufort scale still useful today given that we have precise wind speed instruments?+
Yes, it remains widely used in marine forecasts and general weather communication because a simple 0-12 category is easier for the public to interpret quickly than a raw speed number, and it still usefully summarizes what conditions to expect at sea or on land.
Why do the wind speed ranges get wider at higher Beaufort numbers?+
The scale's categories were defined around distinguishable, observable effects rather than equal speed increments, and the practical difference in effects between very high wind speeds becomes harder to visually distinguish, so the higher categories span a wider range of actual wind speed than the lower ones.