Calculate wind load, area, wind speed, or pressure coefficient from any three inputs with unit options for area, speed, and force in common units.
Customize This Calculator
Build your own version. Describe what you want changed, added, or compared.
Related Calculators
- Concrete Shear Capacity Calculator
- Axial Force Calculator
- Weld Section Modulus Calculator
- Overburden Pressure Calculator
- All Construction Calculators
Wind Loading Formula
The calculator uses the standard imperial wind pressure relationship. Inputs are converted to base units before calculation: area in square feet, wind speed in mph, and wind load in pounds-force.
Rearranged formulas are used when a different value is missing.
- F = wind load, or total wind force, in pounds-force (lbf)
- A = exposed area in square feet (sq ft)
- V = wind speed in miles per hour (mph)
- Cp = pressure coefficient, unitless
- 0.00256 = conversion constant for wind pressure when wind speed is in mph and pressure is in lb/sq ft
If you leave wind load blank, the calculator multiplies wind pressure by the exposed area to find total force. If you leave area blank, it solves for the exposed area needed to produce the entered force. If you leave wind speed blank, it solves for the wind speed that would create the entered load. If you leave pressure coefficient blank, it solves for the coefficient implied by the other values.
Common Wind Speed and Pressure Reference Values
The pressure below uses q = 0.00256V². It does not include the pressure coefficient or area.
| Wind speed | Velocity pressure | General description |
|---|---|---|
| 30 mph | 2.30 psf | Strong breeze |
| 60 mph | 9.22 psf | Severe wind |
| 90 mph | 20.74 psf | High design-level wind in many areas |
| 120 mph | 36.86 psf | Hurricane-level design wind |
Typical Pressure Coefficient Ranges
| Surface or object | Typical pressure coefficient | Use note |
|---|---|---|
| Flat plate facing wind | 1.0 to 1.3 | Common rough estimate for signs and panels |
| Long round pole or cylinder | 0.6 to 1.2 | Depends on shape, surface, and flow conditions |
| Building wall zone | Varies by code zone | Use the coefficient from the applicable design standard |
Example Calculations
Example 1: Calculate wind load
You have an exposed area of 50 sq ft, a wind speed of 90 mph, and a pressure coefficient of 1.2.
The wind load is 1,244.16 lb.
Example 2: Calculate wind speed
You have a wind load of 500 lb, an exposed area of 40 sq ft, and a pressure coefficient of 1.0.
The wind speed is 69.88 mph.
FAQs
What does exposed area mean?
Exposed area is the area that wind acts on. For a flat rectangular sign, it is usually width times height. For round or irregular objects, use the projected area facing the wind, not the full surface area.
What pressure coefficient should you use?
The pressure coefficient depends on shape, wind direction, surface type, and design method. For a simple flat surface facing the wind, a value near 1.0 is often used for rough estimates. For building design or safety-critical work, use the coefficient required by the applicable building code or engineering standard.
Why does wind speed have such a large effect on wind load?
Wind load changes with the square of wind speed. If wind speed doubles, the wind pressure becomes four times larger, assuming the area and pressure coefficient stay the same.
