๐จ Beaufort Wind Scale Converter
| Beaufort number | Wind speed (m/s) | Wind speed (km/h) | Description |
|---|---|---|---|
| 0 | 0.0โ0.2 | 0.0โ0.7 | Calm |
| 1 | 0.3โ1.5 | 1.1โ5.4 | Light air |
| 2 | 1.6โ3.3 | 5.8โ11.9 | Light breeze |
| 3 | 3.4โ5.4 | 12.2โ19.4 | Gentle breeze |
| 4 | 5.5โ7.9 | 19.8โ28.4 | Moderate breeze |
| 5 | 8.0โ10.7 | 28.8โ38.5 | Fresh breeze |
| 6 | 10.8โ13.8 | 38.9โ49.7 | Strong breeze |
| 7 | 13.9โ17.1 | 50.0โ61.6 | Near gale |
| 8 | 17.2โ20.7 | 61.9โ74.5 | Gale |
| 9 | 20.8โ24.4 | 74.9โ87.8 | Strong gale |
| 10 | 24.5โ28.4 | 88.2โ102.2 | Storm |
| 11 | 28.5โ32.6 | 102.6โ117.4 | Violent storm |
| 12 | 32.7+ | 117.7+ | Hurricane |
Enter a wind speed (km/h, m/s, or mph) to determine the Beaufort wind force scale number โ the internationally used 13-level scale (0โ12) based on the standard adopted by the World Meteorological Organization (WMO) and others.
How to use
- Enter a wind speed value.
- Select the unit (km/h, m/s, or mph).
- The matching Beaufort number and description are shown.
How the calculation works
This tool converts the wind speed you enter to metres per second and compares it with the boundaries in the World Meteorological Organization (WMO) and Japan Meteorological Agency tables to find the Beaufort force, from 0 to 12. Each force covers a range defined to 0.1 m/s, for example: Force 0 (calm): 0.0โ0.2 m/s Force 3 (gentle breeze): 3.4โ5.4 m/s Force 6 (strong breeze): 10.8โ13.8 m/s Force 8 (gale): 17.2โ20.7 m/s Force 12 (hurricane force): 32.7 m/s and above Because the table uses 0.1 m/s steps, the input is rounded to 0.1 m/s before comparing. km/h is divided by 3.6, and mph is converted using 1 mile = 1609.344 m. The table also shows each range in km/h for reference.
Worked example
Wind speed 25 km/h 25 รท 3.6 โ 6.9 m/s โ force 4 (moderate breeze: 5.5โ7.9 m/s) Wind speed 24.5 m/s โ force 10 (storm) Wind speed 24.4 m/s โ force 9 (strong gale) Wind speed 40 mph 40 ร 1609.344 รท 3600 โ 17.9 m/s โ force 8 (gale)
Things to be aware of
- Forecast wind speeds are 10-minute averages. Gusts can reach roughly 1.5 to 2 times the average.
- Tropical cyclone intensity categories (such as the SaffirโSimpson scale) are based on maximum sustained winds and use different criteria from the Beaufort scale.
- The Beaufort scale ends at force 12. Some regions extend it to force 17 for typhoons, but that extension is not used here.
FAQ
What is the Beaufort wind force scale?
An international standard scale devised in 1805 by Royal Navy officer Francis Beaufort, ranking wind force from 0 (calm) to 12 (hurricane) across 13 levels. It's still used today by organizations like the World Meteorological Organization (WMO).
How are the level boundaries determined?
The World Meteorological Organization (WMO) and Japan Meteorological Agency tables define each force by a wind speed range in m/s, to 0.1 m/s โ force 4 is 5.5โ7.9 m/s and force 10 is 24.5โ28.4 m/s, for example. This tool uses those m/s boundaries; speeds entered in km/h or mph are converted to m/s first.
I heard it looks different at sea versus on land?
The Beaufort scale was originally defined based on how a sailing ship's sails behaved at sea, but land-based indicators (like how trees sway or smoke drifts) were later added for each level too. This tool determines the level from wind speed alone.