The Beaufort Scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale.
Below is a table showing the Beaufort Scale with speeds in knots, miles per hour and kilometers per hour.
| Wind Force |
Description |
km/h | mph | knots | Specifications |
| 0 | Calm | <1 | <1 | <1 | Smoke rises vertically |
| 1 | Light Air | 1-5 | 1-3 | 1-3 | Direction shown by smoke drift but not by wind vanes |
| 2 | Light Breeze | 6-11 | 4-7 | 4-6 | Wind felt on face; leaves rustle; wind vane moved by wind |
| 3 | Gentle Breeze | 12-19 | 8-12 | 7-10 | Leaves and small twigs in constant motion; light flags extended |
| 4 | Moderate Breeze | 20-28 | 13-18 | 11-16 | Raises dust and loose paper; small branches moved. |
| 5 | Fresh Breeze | 29-38 | 19-24 | 17-21 | Small trees in leaf begin to sway; crested wavelets form on inland waters. |
| 6 | Strong Breeze | 38-49 | 25-31 | 22-27 | Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty. |
| 7 | Near Gale | 50-61 | 32-38 | 28-33 | Whole trees in motion; inconvenience felt when walking against the wind. |
| 8 | Gale | 62-74 | 39-46 | 34-40 | Twigs break off trees; generally impedes progress. |
| 9 | Strong Gale | 75-88 | 47-54 | 41-47 | Slight structural damage (chimney pots and slates removed). |
| 10 | Storm | 89-102 | 55-63 | 48-55 | Seldom experienced inland; trees uprooted; considerable structural damage |
| 11 | Violent Storm | 103-117 | 64-72 | 56-63 | Very rarely experienced; accompanied by widespread damage. |
| 12 | Hurricane | 118 plus | 73 plus | 64 plus | Devastation |
About Sir Francis Beaufort
Measuring Wind Speeds
