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Wind Pressure Calculator

Enter the wind speed in m/s to get the wind pressure in pascals and pounds per square foot.

Result

383.13 Pa
8.00 psf

How it is calculated

Enter the wind speed v in metres per second. The tool computes the dynamic pressure q = 0.613 × v² in pascals (Pa), then converts it to pounds per square foot with psf = Pa × 0.0208854. The constant 0.613 is half the standard air density at sea level (1.225 kg/m³) and assumes that density; thinner air at altitude or hot weather gives somewhat lower pressure.

Because speed is squared, the pressure grows quickly: doubling the speed quadruples q. Only a negative speed gives no result; zero returns 0. The figure is the free-stream pressure only. It does not include shape, height, exposure or gust factors that a design code applies on top, so it is not a design load by itself. Speeds in km/h, mph or knots must be converted to m/s first.

Worked example

A steady wind of 25 m/s. Square the speed: 25² = 625. Multiply by 0.613: 625 × 0.613 = 383.13 Pa. Convert to imperial: 383.13 × 0.0208854 = 8.00 psf. The result is 383.13 Pa or 8.00 psf. At 50 m/s the pressure would be four times larger, 1,532.50 Pa.

Try this example →

Common mistakes

  • Entering km/h or mph as if it were m/s. 90 km/h is 25 m/s; typing 90 gives a pressure about thirteen times too high.
  • Expecting pressure to scale in a straight line with speed. Because of the square, 50 m/s gives four times the pressure of 25 m/s, not twice.
  • Using the result as the final design load on a sign or panel. It is the base pressure only, and codes multiply it by shape, exposure and gust coefficients.
  • Multiplying by a surface area in square metres and reading the answer as kilograms. Pa times m² gives newtons, not kilograms.
  • Applying the sea-level constant at high altitude. The 0.613 factor assumes standard air density, so the pressure is overestimated where the air is thinner.

Sources

  • Dynamic Pressure — NASA Glenn Research Center, Beginner's Guide to Aeronautics

About this calculator

This calculator applies the fundamental dynamic pressure formula from fluid mechanics, q = ½ρv², where ρ is air density. Using the standard sea-level air density of 1.225 kg/m³, the equation simplifies to the practical form q = 0.613 × v², giving wind pressure in pascals for a wind speed in metres per second. The same relationship underlies the imperial form used in U.S. codes, q = 0.00256 × V² (psf, V in mph), part of the wind-load provisions in ASCE 7.

Structural and civil engineers use this pressure as the base value for calculating wind loads on signs, cladding panels, fences, solar arrays and building facades, before applying shape and exposure coefficients for a full design load.

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Comments (1)

  • Editorial team

    For anything that must survive storms, gusts matter more than the average wind, because pressure follows the square of speed. A 25 m/s gust gives 383.13 Pa, about 1.56 times the 245.20 Pa of a steady 20 m/s. So compare the pressure for the gust speed your local weather service reports, not only the mean. For a structure, ask an engineer for the design value. Do you work with m/s, km/h or mph?

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