Convert a wind speed to its Beaufort force number and description.
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How do you convert wind speed to a Beaufort scale number?
The Beaufort scale relates a wind speed to its force number (0 to 12), name and conditions, from calm to hurricane force. Enter a speed in km/h, mph, m/s or knots to get the matching force. For example, 25 km/h (about 6.9 m/s) is Beaufort force 4, a "moderate breeze" — handy when you have no anemometer reading.
Understanding your result
The Beaufort scale relates wind speed to observable effects on land and sea, which is handy when you don’t have an anemometer reading.
Assumptions and limitations
It classifies a steady wind speed into the Beaufort force from 0 to 12 with its standard description. It relates only to sustained wind, not sudden gusts, and the observable effects it describes are general guides rather than a precise reading for your exact location.
Worked example
25 km/h (about 6.9 m/s) is Beaufort force 4, a “moderate breeze”.
How to use this tool
- Enter the wind speed.
- Choose the unit (km/h, mph, m/s or knots).
- Press Calculate.
About the Beaufort Wind Scale Calculator
The Beaufort Wind Scale Calculator turns a wind speed into its Beaufort force (0–12) with the name and the conditions you’d expect, from calm to hurricane force.
Who should use this tool
Sailors, kite-flyers, drone pilots and gardeners judging conditions, weather enthusiasts, and anyone who wants to turn a wind speed into its Beaufort force number with the descriptive name and the effects you would expect from calm to hurricane force.
Benefits
- Turns a wind speed into its Beaufort force and name
- Describes the conditions you would expect at that force
- Useful when you have no anemometer to hand
- Covers the full scale from calm to hurricane force
Practical use cases
- Judging whether conditions are safe to sail or fly a drone
- Interpreting a forecast wind speed in familiar terms
- Deciding if it is too windy for garden or roof work
- Learning how wind speed maps to real-world effects
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Frequently asked questions
What is hurricane force on the Beaufort scale?
Force 12 — winds of 32.7 m/s (about 118 km/h) or more, causing severe, devastating damage.
What wind speed counts as hurricane force on the Beaufort scale?
Hurricane force is Beaufort force 12, the top of the scale, reached at a sustained wind speed of about 118 kilometres per hour or more. It brings widespread devastation. The scale runs from force 0 for calm air up to force 12, each step describing progressively stronger effects.
Is the Beaufort scale based on wind speed or observed effects?
Both. It was originally defined by the observable effects of wind on land and sea, and each force now also corresponds to a range of wind speeds. That link lets you estimate the force from what you see when no anemometer reading is available.