Windsock Calculator — Angle, Beaufort Scale & Wind Speed
Find out what a windsock looks like at any wind speed and where that speed falls on the Beaufort scale. Enter the wind speed in any unit to get the sock angle, inflation level and Beaufort number.
Unit
Mostly extended — 0° = limp, 90° = fully extended
- 1
Speed in knots
25 ÷ 1.852 = 13.5 - 2
Windsock angle
min(90, 90 × 13.5 ÷ 15) = 81Fully extended at 15 knots (FAA/ICAO standard); angle is proportional below.
How does this calculator work?
Windsock angle ≈ 90° × V_kt / 15, capped at 90°. Fully extended at 15 kt (28 km/h); half extended ≈ 7 kt. Enter speed in km/h, knots, m/s or mph to get the angle and Beaufort number (0 = calm, 12 = hurricane).
Formula
How this is calculated
A windsock is a conical fabric sleeve mounted on a freely rotating mast. Wind inflates and extends it in the downwind direction, giving pilots and ground crew a quick visual indication of wind speed and direction. The degree of inflation and the angle the sock makes with the mast pole are the key indicators.
The FAA and ICAO standard defines a fully extended (90° from pole) windsock as indicating at least 15 knots (27.8 km/h). Below that speed the sock hangs at an angle roughly proportional to the wind: half extended corresponds to about 7–8 knots, and the sock barely moves below 3 knots. This calculator uses a linear model (angle = 90° × V_kt / 15) capped at 90°, which matches the ICAO standard reference points.
The Beaufort scale, originally developed by Francis Beaufort in 1805 and still used by meteorological services worldwide, classifies wind from 0 (calm) to 12 (hurricane force) based on observed effects at sea or on land. The scale thresholds used here are the WMO (World Meteorological Organization) standard values in km/h.
Frequently asked questions
A windsock extended horizontally (90° from the mast pole) indicates winds of at least 15 knots (27.8 km/h, Beaufort 4–5). Aviation regulations often require pilots to assess crosswind components from the sock angle before landing.
Divide the angle by 90° and multiply by 15 knots: a sock at 45° indicates about 7–8 knots. This is a simplified model — actual sock behaviour also depends on the sock's weight, diameter and fabric porosity.
There is no single Beaufort threshold for aviation danger — it depends on the aircraft type, pilot experience and runway orientation relative to the wind. However, Beaufort 7+ (near gale, > 50 km/h) often exceeds small aircraft crosswind limits and is a strong cue to check notam and weather carefully.
Also known as
TG we-Calculate Editorial Team. (2026). Windsock Calculator — Angle, Beaufort Scale & Wind Speed [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/windsock-calculator
TG we-Calculate Editorial Team. "Windsock Calculator — Angle, Beaufort Scale & Wind Speed." TG we-Calculate. 2026. https://we-calculate.com/calculator/windsock-calculator.
TG we-Calculate Editorial Team, "Windsock Calculator — Angle, Beaufort Scale & Wind Speed," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/windsock-calculator
@misc{wecalculate_windsock_calculator, title = {Windsock Calculator — Angle, Beaufort Scale & Wind Speed}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/windsock-calculator}}, year = {2026}, note = {TG we-Calculate} }
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