Wind Speed to PSF Calculator

Square the wind speed in miles per hour and multiply by 0.00256. The result is the basic wind pressure in pounds per square foot: q = 0.00256 × V². A 100 mph wind gives 25.6 psf, and 175 mph, the design wind speed in Miami-Dade, gives about 78.4 psf. The 0.00256 constant comes from the density of standard air at sea level.

Divide the pressure by 0.00256 and take the square root: V = √(q ÷ 0.00256). A basic pressure of 50 psf corresponds to about 140 mph, and 75 psf to about 171 mph. Because pressure grows with the square of speed, doubling the wind speed makes the pressure four times larger.

No. The basic pressure is a starting point. The building code then adjusts it for roof height, terrain exposure and wind direction, and multiplies it by pressure coefficients that depend on where the window sits on the wall and how big it is. Corner windows and small panes see more suction than the basic number suggests. To estimate the positive and negative design pressure for a specific window or door, use our wind load calculator.

Not directly. A DP 50 rating means the product was tested to resist 50 psf of design pressure, but the wind speed that produces 50 psf on a given opening depends on the house height, exposure, the opening's location and size, and the code's load factors. Plugging 50 psf into the psf to mph formula gives a number that is not the product's wind speed rating. What matters for a permit is that the product's positive and negative ratings meet the pressures calculated for each opening.

Under the 2023 Florida Building Code, a typical home (Risk Category II) uses 175 mph in Miami-Dade and 170 mph in Broward, both in the High-Velocity Hurricane Zone, and 160 to 170 mph in Palm Beach County depending on location. These are 3-second gust speeds used for design, not forecasts of a particular storm.

No, the two use different measurements. Building-code design wind speeds are 3-second peak gusts at 33 ft above open ground. The Saffir-Simpson hurricane categories are based on 1-minute sustained winds. A design speed is a code input for sizing structures, so it should not be read as a promise that a building or product will come through any specific hurricane undamaged.

Those two inputs turn the basic pressure into the ASCE 7-22 velocity pressure, qh, which is what the code actually multiplies by its pressure coefficients. Wind is faster higher off the ground and over open water, so a taller house or a waterfront lot (Exposure D) raises qh. The converter also applies the 0.85 directionality factor used for components and cladding, and shows the 0.6 factor used for allowable stress design, the basis of NOA and product approval ratings.