Wind pushes on everything in its way, and the force grows with the square of the wind speed: a 100 km/h gust pushes four times harder than a 50 km/h one. Engineers use this to size signs, roofs, solar mounts and fences.
How to use the Wind Load Calculator
- Wind speed
- Air density
- Surface area
- Force (drag) coefficient
- Wind angle to the surface
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the wind speed, area, force coefficient (2.0 is typical for flat signs and plates) and the angle between the wind and the surface (90° = face on).
Inputs explained
| Field | What to enter |
|---|---|
| Wind speed | Units: km/h, m/s, mph, knots, ft/s |
| Air density | Units: kg/m³, g/cm³, g/mL, lb/ft³, lb/in³ |
| Surface area | Units: m², cm², mm², km², in², ft² |
| Force (drag) coefficient | A number |
| Wind angle to the surface | Units: °, rad, arcmin, arcsec, mrad |
What each result means
- Dynamic (velocity) pressure = 0.5×[Air density]×[Wind speed]^2
- Wind load = 0.5×[Air density]×[Wind speed]^2×[Surface area]×[Force (drag) coefficient]×sin(rad([Wind angle to the surface]))
- Equivalent weight = [Wind load]÷9.80665
Example values
How the main result changes when Wind speed changes and everything else stays at the example values above:
| Wind speed (km/h) | Wind load (N) |
|---|---|
| 50 | 472.608 |
| 75 | 1,063.3681 |
| 100 | 1,890.4321 |
| 125 | 2,953.8002 |
| 150 | 4,253.4722 |
| 200 | 7,561.7284 |
Formula
q = ½·ρ·v², F = q·A·C_d·sin α
Worked example
Inputs — Wind speed: 100 km/h; Air density: 1.225 kg/m³; Surface area: 2 m²; Force (drag) coefficient: 2; Wind angle to the surface: 90 °.
Results — Dynamic (velocity) pressure = 472.60802 Pa; Wind load = 1,890.4321 N; Equivalent weight = 192.7704 kgf.
Key terms
- Dynamic pressure
- Kinetic energy per unit volume of moving air.
Frequently asked questions
Why does wind load grow so fast with speed?
It is proportional to v².
What force coefficient should I use?
About 1.2 for long cylinders, 2.0 for flat signs, more for some open frames.
Do building codes use this?
Codes add gust, exposure and importance factors – use them for real designs.
What is velocity pressure?
The dynamic pressure of the wind, ½ρv².