Sat May 19 2012 | 21:35:52 GMT+8

Wind Calculator

The most commonly used scale for measuring wind force is the Beaufort scale. The Beaufort wind scale was developed in 1805 by Sir Francis Beaufort of the Royal Navy. He wanted a consistent way to measure wind force on fighting ships. Today's version states the wind's effects on land as well as sea.

Other measurements for wind speed are knots, meters per second (m/s), kilometers per second (km/h) and miles per hour (mph). The relation between these different metrics is as follows:
v = 0.836 B3/2 m/s, where v is the equivalent wind speed measured in m/s and B is the Beaufort scale number
1 m/s = 1,944 knots
1 m/s = 2,6 km/h and
1 m/s = 2,237 mph

In the calculator below, place the number you wish in the textbox and choose the scale it is in (e.g. Beaufort, knots, etc.). By pressing "Convert", the wind calculator will convert that number in all different measurement scales.

Wind speed:

The Beaufort scale

Beaufort number Wind speed Description Wave height Sea conditions Land conditions Sea state photo
km/h mph kts m/s m ft
0 <1 <1 <1 <0.3 Calm 0 0 Flat. Calm. Smoke rises vertically.
1 1-5 1-3 1-2 0.3-1.5 Light air 0.1 0.33 Ripples without crests. Wind motion visible in smoke.
2 6-11 3-7 3-6 1.5-3.3 Light breeze 0.2 0.66 Small wavelets. Crests of glassy appearance, not breaking Wind felt on exposed skin. Leaves rustle.
3 12-19 8-12 7-10 3.3-5.5 Gentle breeze 0.6 2 Large wavelets. Crests begin to break; scattered whitecaps Leaves and smaller twigs in constant motion.
4 20-28 13-17 11-15 5.5-8.0 Moderate breeze 1 3.3 Small waves. Dust and loose paper raised. Small branches begin to move.
5 29-38 18-24 16-20 8.0-10.8 Fresh breeze 2 6.6 Moderate (1.2 m) longer waves. Some foam and spray. Branches of a moderate size move. Small trees begin to sway.
6 39-49 25-30 21-26 10.8-13.9 Strong breeze 3 9.9 Large waves with foam crests and some spray. Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult.
7 50-61 31-38 27-33 13.9-17.2 High wind, Moderate Gale, Near Gale 4 13.1 Sea heaps up and foam begins to streak. Whole trees in motion. Effort needed to walk against the wind.
8 62-74 39-46 34-40 17.2-20.7 Fresh Gale 5.5 18 Moderately high waves with breaking crests forming spindrift. Streaks of foam. Twigs broken from trees. Cars veer on road.
9 75-88 47-54 41-47 20.7-24.5 Strong Gale 7 23 High waves (6-7 m) with dense foam. Wave crests start to roll over. Considerable spray. Larger branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. Damage to circus tents and canopies.
10 89-102 55-63 48-55 24.5-28.4 Whole Gale/Storm 9 29.5 Very high waves. Large patches of foam from wave crests give the sea a white appearance. Considerable tumbling of waves with heavy impact. Large amounts of airborne spray reduce visibility. Trees are broken off or uprooted, saplings become bent and/or deformed, poorly attached asphalt shingles and shingles in poor condition peel off roofs.
11 103-117 64-72 56-63 28.4-32.6 Violent storm 11.5 37.7 Exceptionally high waves. Very large patches of foam, driven before the wind, cover much of the sea surface. Very large amounts of airborne spray severely reduce visibility. Widespread vegetation damage. Many roof shingles and surfaces sustain damage; gravel may be blown from flat roofs.
12 118+ 73+ 64+ 32.6+ Hurricane force 14+ 46+ Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility. Considerable and widespread damage to vegetation, a few windows broken, structural damage to mobile homes and poorly constructed sheds and barns. Debris may be hurled about.