The wind force a wall, sign or panel has to resist — not just the wind speed. ASCE 7 velocity-pressure method, with exposure category, height and a force coefficient turned into pounds of design load.
Wind Speed Is Not Wind Load
A wind speed tells you how fast the air moves; a wind load tells you how hard it pushes. The jump between them is the velocity pressure, and it climbs with the square of the speed — a 115 mph wind pushes nearly four times harder than a 60 mph one. This calculator carries the speed all the way to the pounds of force your wall, sign or panel actually has to resist.
The Velocity Pressure
Kz grows with height and openness of the terrain — wind is slower near the ground and in cities, faster up high and over open or coastal ground. The exposure category (B, C or D) and the height set it through the ASCE power-law profile. Kzt accounts for hills and Kd for wind direction.
From Pressure to Force
The design pressure on the surface is the velocity pressure times a gust factor G and a force coefficient Cf that depends on the shape — a solid wall or sign is about 1.3, a round tank closer to 0.7, an open lattice frame around 2.0. Multiply by the area and you get the total force:
Frequently Asked Questions
What basic wind speed do I use?
It comes from the ASCE 7 wind maps for your location and risk category, typically 110 to 150 mph in much of the US and higher on hurricane coasts. Check the map or your local code.
Which exposure category?
B for suburban, wooded or built-up areas; C for open terrain with scattered obstructions; D for flat, unobstructed ground and coastlines. When in doubt, the more open category is more conservative.
Is this a full code check?
No. It is the velocity-pressure method for one surface. A complete design also handles internal pressure, windward and leeward faces, cladding zones and load combinations – work for a licensed engineer.
Related calculators
- Retaining Wall Calculator — another lateral-load stability check.
- Beam Load Calculator — carry the wind force into the framing.
- Mechanical Force Calculator — general force relationships.
- Engineering Unit Converter — pressure, force and speed units.