Wind Speed Converter
Convert wind speed between Beaufort scale, mph, km/h, knots, and m/s.
Includes Beaufort reference from calm to hurricane force with land and sea descriptions.
Wind speed is measured in multiple units worldwide — knots (nautical miles per hour) in aviation and maritime, km/h in most weather forecasts, mph in the United States, and m/s in scientific contexts. The Beaufort scale translates speed into observable descriptions of wind effects, which is useful when you don’t have instruments.
Conversion formulas: knots × 1.852 = km/h km/h × 0.621 = mph m/s × 3.6 = km/h mph × 0.447 = m/s
Beaufort Scale reference:
| Beaufort | mph | km/h | Description |
|---|---|---|---|
| 0 | 0 | 0 | Calm, smoke rises vertically |
| 1 | 1–3 | 1–5 | Light air, smoke drifts |
| 2 | 4–7 | 6–11 | Light breeze, leaves rustle |
| 3 | 8–12 | 12–19 | Gentle breeze, twigs move |
| 4 | 13–18 | 20–28 | Moderate breeze, branches sway |
| 5 | 19–24 | 29–38 | Fresh breeze, small trees sway |
| 6 | 25–31 | 39–49 | Strong breeze, large branches sway |
| 7 | 32–38 | 50–61 | Near gale, whole trees sway |
| 8 | 39–46 | 62–74 | Gale, difficult to walk |
| 9 | 47–54 | 75–88 | Strong gale, roof damage |
| 10 | 55–63 | 89–102 | Storm, trees uprooted |
| 11 | 64–72 | 103–117 | Violent storm, widespread damage |
| 12 | 73+ | 118+ | Hurricane force |
Worked example: A forecast shows 45 knots. 45 × 1.852 = 83.3 km/h = 51.7 mph → Beaufort 9 (Strong Gale)
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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