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Wind: friend and foeWhat is the wind load on a structure?How to use the wind load calculatorFAQs

The wind load calculator enables you to compute the wind force on any structure. Whether it is a roof, a sign, or a steel structure, with this wind force calculator, you can determine the wind pressure created on it depending on the wind speed, helping you make sure it's sturdy enough to withstand even the worst storm.

## Wind: friend and foe

Whenever humans erect a structure, an eternal battle is raged against nature to keep it standing. Erosion disassembles our constructions bit by bit, roofs collapse under the load of snow, and floods and fires can have your life's work undone in seconds.

But one of the most damaging elements is one which we direly rely on for our survival: air. . The excessive wind load on roofs collapses buildings and endangers lives. But don't worry; this wind force calculator is here to help you estimate the wind load exerted on any structure, depending on the wind speed and the structure's surface area. So, you can make sure that an unstable roof, window, or sign never threatens your loved ones and your property.

And maybe safe in the knowledge that the wind will not hurt you, you can make use of it and create sustainable, clean, and cheap energy with your very own wind turbine (visit wind turbine calculator, for more). Or use it for some fun exercise like windsurfing or the even more challenging kitesurfing. We've got your back with our windsurfing calculator and kiteboarding calculator.

## What is the wind load on a structure?

The force of air particles hitting a surface is known as the wind load on a specific structure. To calculate the precise force, we need to have more information about the wind and the structure:

• The air molecules colliding with an object create a dynamic pressure, depending on wind velocity and the air density. The air density is a function of humidity, temperature, and pressure. In this calculator, we assume a default value of $1.225~\mathrm{kg/m^3}$ or $0.0765~\mathrm{psi}$, equivalent to a temperature of $15\degree~\mathrm{C}$ or $59\degree~\mathrm{F}$ at sea level. These conditions are known as standard temperature and pressure (STP). If you live at a location with significantly different conditions, we recommend using the air density calculator to determine your air density and adapt the value in this calculator accordingly.

• The wind load also depends on the effective surface area of your structure. The effective surface is the surface orthogonal to the wind direction. Under the assumption that the wind is always parallel to the horizon, we can calculate the effective surface from the total surface and the angle. For example, a surface at 90° to the ground experiences much more wind load than a $45\degree$ roof pitch, even if the wind speed and surface area are the same.

Considering all these factors, the wind pressure calculator determines the dynamic pressure and the wind load:

Dynamic pressure = 0.5 × Air density × Wind speed²

Wind load = Dynamic pressure × Effective surface = Dynamic pressure × Total surface × sin(angle)

Roof pitch calculator

## How to use the wind load calculator

Here, we will show you how to use the wind load calculator.

1. Set the wind's characteristics, namely the wind velocity and the air density. The default air density should be adequate unless you live in a very hot, cold, or elevated location. In that case, you can determine the air density with the tool linked under the air density field in the calculator and change the value accordingly.

2. Input the important values of your structure: the total surface area and the angle. If you have issues determining the area of your structure, the area calculator might help you. The angle is between the horizon and your structure, so it is the pitch for a roof.

3. The wind force calculator will then provide you with the wind pressure you can expect. So you can estimate the wind load on your roof and safely plan your build without any risk of collapse from storms.

FAQs

### How do I calculate wind load?

1. Multiply the air density by the square of the wind speed.

2. Divide this value by 2 to get the wind's dynamic pressure:

dynamic pressure = 0.5⋅air density⋅wind speed²

3. Multiply the structure's external surface area with the sin of the angle it makes with the horizontal (θ) to get its effective surface area:

effective surface area = surface area⋅sin(θ)

4. Multiply the dynamic pressure with the effective surface area of the structure to obtain the wind load:

wind load = dynamic pressure⋅effective surface area

### What is a 20 psf wind load?

A 20 pounds per square foot (psf) wind load (or dynamic pressure) corresponds to 88.5 mph wind speed. This wind speed is typical in a category one hurricane.

### How much force does 100 mph wind have?

A wind speed of 100 mph results in a dynamic pressure of 25.564 psf. On a 10'×10' vertical wall, the wind load would be 2556.4 lbs. Here's how you calculate this:

1. Multiply the air density with the square of the wind speed and 0.5:

dynamic pressure = 0.5⋅1.225 kg/m³⋅(100 mph)² = 0.5⋅1.225 kg/m³⋅(44.7 m/s)² = 1224 Pa

2. Convert 1224 Pa into pounds per square foot (psf):

1224 Pa⋅0.020885 psf/Pa = 25.564 psf

3. Multiply the dynamic pressure with the wall's effective surface area to obtain the wind load:

wind load = 25.564 psf⋅100 ft² = 2556.4 lbs

### What is the wind load at 70 mph?

70 mph wind will cause 12.527 psf dynamic wind pressure. On a 100 sq. ft wall, this would mean a wind load of 1252.7 lbs. The following steps will help you verify this:

1. Multiply the air density by the square of the wind speed and 0.5:

dynamic pressure = 0.5⋅1.225 kg/m³⋅(70 mph)² = 0.5⋅1.225 kg/m³⋅(31.3 m/s)² = 599.8 Pa

2. Convert this into pounds per square foot (psf):

599.8 Pa⋅0.020885 psf/Pa = 12.527 psf

3. Multiply the dynamic pressure with the wall's effective surface area to obtain the wind load:

wind load = 12.527 psf⋅100 ft2 = 1252.7 lbs

### How much force does 50 mph wind have?

50 mph wind speed will cause 6.391 psf dynamic pressure. On a 100 ft2 vertical wall, the wind load would be 639.1 lbs. To calculate this answer, follow these steps:

1. Multiply the air density by the square of the wind speed and 0.5:

dynamic pressure = 0.5⋅1.225 kg/m³⋅(50 mph)² = 0.5⋅1.225 kg/m³⋅(22.35 m/s)² = 306 Pa

2. Convert 306 Pa into pounds per square foot (psf):

306 Pa⋅0.020885 psf/Pa = 6.391 psf

3. Multiply the dynamic pressure with the wall's effective surface area to obtain the wind load:

wind load = 6.391 psf⋅100 ft² = 639.1 lbs

### How do I convert wind speed to force?

To convert the wind speed to the force acting on a surface, follow these steps:

1. Multiply the air density with the square of the wind speed.

2. Divide this value by 2 to get the wind's dynamic pressure:

dynamic pressure = 0.5⋅air density⋅wind speed²

3. Multiply the surface's area with the sin of the angle it makes with the horizontal (θ) to get its effective area:

effective surface area = area⋅sin(θ)

4. Multiply the dynamic pressure with the effective surface area to obtain the force the wind applies on the surface:

wind load = dynamic pressure⋅effective surface area