# Windsock Calculator

URL: https://speedycalculator.com/calculators/everyday-life/windsock/
Last updated: 2026-10-25

> The windsock calculator reads wind speed from a standard five-segment aviation windsock: each fully inflated segment represents about 3 knots, and a fully extended sock means 15 knots or more.

## Inputs

- Inflated segments

## Results

- Wind speed
- Description

## Formula

```
Wind speed ≈ 3 knots × number of inflated segments (maximum 15 kt)
```

## Explanation

Airfield windsocks in many countries follow an FAA/ICAO pattern of five alternating stripes. The sock is designed so that each additional segment that fills and lifts corresponds to roughly 3 knots more wind. Pilots use it to estimate wind direction and strength before take-off and landing.

### How to use the Windsock Calculator

- **Inflated segments**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Count how many segments are filled and standing out from the pole, including partly lifted ones as fractions.

### Tips

- Use your own measured figures – fuel economy, speed and prices vary a lot with driving style, traffic, load and season.
- Pick the unit in each field's menu (miles or kilometres, mpg or L/100 km); the calculator converts everything for you.
- Fill up to the brim twice and divide the distance by the fuel added to measure real fuel economy.
- For vehicle modifications, treat results as a starting point and confirm with the parts maker or a professional mechanic.

### Common mistakes to avoid

- Mixing US and imperial (UK) gallons – a UK gallon is about 20% bigger.
- Using the advertised fuel economy instead of real-world figures.
- Forgetting tolls, parking and wear and tear when comparing driving with public transport.

### Example values

How the main result changes when **Inflated segments** changes and everything else stays at the example values above:

Inflated segmentsWind speed (knots)1.54.52.256.8393.7511.24.513.5

## Worked example

Inputs — Inflated segments: 3.

Results — **Wind speed = 9 knots**; Description = Moderate breeze.

## FAQ

**How many knots is a full windsock?**
A standard windsock fully extends at about 15 knots.

**What does a limp windsock mean?**
Calm or very light wind, under about 3 knots.

**Which way is the wind blowing?**
The sock points downwind – the wind is coming from the end attached to the pole.

**What formula does the Windsock Calculator use?**
Wind speed ≈ 3 knots × number of inflated segments (maximum 15 kt).


## Sources

- [FAA Advisory Circular 150/5345-27 – Specification for wind cone assemblies](https://www.faa.gov/)