Beaufort Scale Converter
Wind speed to Beaufort force 0–12 with land and sea effects.
About this tool
Enter a wind speed in any unit to see its Beaufort force and name, what you'd see on land and at sea, and typical wave height. The full table lists every force with its speed range in mph, km/h and knots.
The Beaufort wind scale
Francis Beaufort, a Royal Navy officer, devised the scale in 1805 so sailors could estimate wind strength from what they could see. It runs from force 0, calm, where smoke rises straight up, to force 12, hurricane force, above 64 knots (74 mph). In between: force 3 gentle breeze makes flags extend; force 5 fresh breeze (17–21 knots, about 19–24 mph) makes small trees sway and puts white horses on the sea; force 7 near gale makes walking hard; force 8 gale breaks twigs; force 10 storm uproots trees. The scale is still used in UK Met Office shipping forecasts and many marine and mountain forecasts. The converter follows the World Meteorological Organization knot ranges, so 25 mph (21.7 knots) is force 5, a fresh breeze. Honest limits: converted ranges are rounded; wave heights are open-sea figures, much smaller near the shore; gusts are often 30–50% stronger than the average wind a forecast gives. The feels-like temperature calculator and the speed of sound calculator are related.
Frequently asked questions
What wind speed is a gale?
Force 8 gale is 34 to 40 knots, about 39 to 46 mph or 63 to 74 km/h.
What Beaufort force is hurricane force?
Force 12: 64 knots (74 mph, 118 km/h) and above.
Is the Beaufort scale still used?
Yes, in UK shipping forecasts and many marine, sailing and mountain forecasts.
Do the speeds include gusts?
No. Beaufort describes the average wind; gusts are often much stronger.
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.