The environment
Wind velocity
Air density
lb/cu ft
The default air density is for 15°C/59°F at sea level. If you need to change this value, check our air density calculator.
The loaded object
Surface area
Surface angle
Dynamic pressure and wind load
Dynamic pressure
Wind load

Wind Load Calculator

By Philip Maus
Last updated: Feb 02, 2021

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. In 2019 alone, storms caused over $40 billion in damage and numerous power cuts. The excessive wind load on roofs collapses buildings and endangers lives. But don't worry, this wind force calculator is here to help you to 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 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. Or use it for some fun exercise like windsurfing or the even more challenging kitesurfing.

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 the humidity, temperature, and pressure. In this calculator, we assume a default value of 1.225 kg/m3 / 0.0765 psi, equivalent to a temperature of 15°C/59°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 experience much more wind load than a 45° roof pitch, even if the wind speed and surface area is 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)

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.

Philip Maus
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