Wind Load Calculator

Wind load is the force that wind exerts on a structure or object. It depends on wind speed, air density, the exposed area of the structure, its shape (drag coefficient), and the angle at which the wind strikes. Engineers use wind load calculations to ensure buildings, signs, roofs, and other structures can withstand design wind events without failure.

Wind load is calculated in two steps. First, compute the dynamic wind pressure: qs = 0.5 × ρ × v², where ρ is air density (kg/m³) and v is wind speed in m/s. Then multiply by area and drag coefficient: F = qs × Cd × A × sin(α). This gives the wind force in Newtons. Our calculator handles all of this automatically once you enter your inputs.

A 20 psf (pounds per square foot) wind load means the wind exerts a pressure of 20 lbf on every square foot of the structure's exposed surface. This corresponds to roughly 958 Pa and is typical of wind speeds around 90–100 mph (145–160 km/h), depending on the drag coefficient of the structure.

At 100 mph (~161 km/h or ~44.7 m/s), the dynamic pressure on a flat surface is approximately 1,227 Pa (25.6 psf). For a 10 m² wall with a drag coefficient of 1.3, the total wind force would be roughly 15,950 N (about 3,585 lbf or 1.6 tonnes). The force increases rapidly with speed since pressure scales with the square of wind velocity.

At 70 mph (~113 km/h or ~31.3 m/s), the dynamic wind pressure is approximately 600 Pa (12.5 psf). The actual wind force on your structure depends on the exposed area and drag coefficient. Use the calculator above with your specific structure dimensions to get an accurate result.

At 50 mph (~80 km/h or ~22.4 m/s), the dynamic pressure is about 307 Pa (6.4 psf). For a standard 10 m² building wall with Cd = 1.3, the resulting wind force would be approximately 3,990 N (898 lbf). While this may seem modest, cumulative wind load over large roof or wall areas can still be structurally significant.

To convert wind speed to force: (1) Convert speed to m/s (divide km/h by 3.6, or multiply mph by 0.447). (2) Calculate dynamic pressure: qs = 0.5 × 1.225 × v². (3) Multiply by the drag coefficient and exposed area: F = qs × Cd × A. The result is in Newtons. Divide by 4.448 to convert to lbf, or divide by 1000 for kN.

Common drag coefficients include: flat plate or signboard (~2.0), rectangular building (~1.3), open truss (~1.5–2.0), and cylinders (~0.5–1.2 depending on Reynolds number). For precise structural engineering work, consult ASCE 7 or EN 1991 standards, as they provide detailed Cd values based on building geometry, height, and exposure category.