Calculadora de Velocidade do Vento — Escala Beaufort
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
B ≈ round((v_km/0,836)^(2/3))
About this calculator
The Wind Speed Calculator on the Beaufort Scale converts wind speed in km/h to the Beaufort scale number (0 to 12). The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea and on land, from calm (Beaufort 0) to hurricane (Beaufort 12). The formula used is B ≈ (v / 0.836)^(2/3), where v is speed in km/h. The result is rounded to the nearest integer.
When to use this calculator? Ideal for sailors, amateur meteorologists, educators, or anyone wanting to understand wind intensity practically. For example, when checking the weather forecast, you can enter the wind speed in km/h and quickly get the Beaufort classification to know if the wind is moderate (force 4) or very strong (force 9). Also useful for outdoor activities like sailing, kite flying, or event safety.
Important cautions: the Beaufort scale is based on visual observations and may vary by environment. On land, wind effects can differ from those at sea. Additionally, the formula is an approximation and may not accurately reflect gusts or extreme conditions. For winds above 118 km/h (Beaufort 12), the scale does not define higher values, but the calculator still outputs 12. Always consult official sources for weather warnings.
Frequently asked questions
What does Beaufort 0 mean?
Beaufort 0 is calm, with winds below 1 km/h. Smoke rises vertically and the sea is mirror-like.
How to convert km/h to Beaufort manually?
Use the formula B = (v / 0.836)^(2/3) and round. For example, 20 km/h: (20/0.836)^(2/3) ≈ 4.2, rounded to Beaufort 4.
Is the Beaufort scale used in Brazil?
Yes, mainly by the Navy and in nautical meteorology. For the general public, weather forecasts usually use km/h or m/s.
What is the difference between Beaufort and the hurricane scale?
The Beaufort scale goes up to 12 (hurricane, winds above 118 km/h). The Saffir-Simpson scale classifies hurricanes from 1 to 5 based on sustained speed.
Can I use this calculator for wind in knots?
Not directly. First convert knots to km/h (1 knot = 1.852 km/h) and then enter the value in km/h.