km/h
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m²
Please enter a valid area in m².
Width × Height facing the wind
-
Please enter a valid drag coefficient.
Auto-filled from shape above
Wind Force
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⚠️ Disclaimer: This calculator provides a physics estimate only. Structural design requires compliance with local building codes (ASCE 7, EN 1991-1-4, AS/NZS 1170.2, etc.) and must be carried out by a licensed structural or civil engineer. Do not use this result alone for any structural design decision.
Sources & Methodology
Wind load formula from ASCE 7-22 and EN 1991-1-4 Eurocode. Air density from NIST Standard Atmosphere. Drag coefficients from ASCE 7 Table 29.4-1.
ASCE 7-22 — Minimum Design Loads for Buildings and Other Structures
ASCE 7 provides the US standard for calculating wind loads on structures. The drag force formula F = 0.5ρC_d Av² is consistent with ASCE 7 Chapter 27 (MWFRS) and Chapter 30 (C&C) methodology.
NIST — Standard Atmosphere (Air Density)
Standard sea level air density ρ = 1.225 kg/m³ at 15°C and 101.325 kPa, used as the default in this calculator. Actual density varies with altitude, temperature, and humidity.
Methodology: Dynamic pressure q = 0.5×ρ×v² (Pa). Wind force F = C_d×A×q (N). Air density ρ = 1.225 kg/m³ (sea level, 15°C). Wind speed conversions: 1 km/h = 1/3.6 m/s. 1 mph = 0.44704 m/s. 1 knot = 0.51444 m/s. Note: ASCE 7 uses 3-second gust speeds. This calculator uses mean wind speed. For structural design, multiply mean wind speed by 1.5–1.7 gust factor to obtain design gust speed.
⏱ Last reviewed: April 2026
How to Calculate Wind Load on Structures and Panels
Wind exerts pressure on any surface it flows against. The force depends on wind speed (squared), the area exposed to wind, the shape of the object (drag coefficient), and air density. Understanding wind loads is critical for designing solar panel mountings, antenna supports, building facades, signage, and all outdoor structures.
The Wind Load Formula
F = ½ ρ C_d A v² q = ½ ρ v²
ρ = air density = 1.225 kg/m³ (sea level) • C_d = drag coefficient • A = projected area (m²) • v = wind speed (m/s)
Example 1 — 2 m² flat plate at 100 km/h (27.78 m/s):
q = 0.5×1.225×27.78² = 472 Pa. F = 1.28×2×472 = 1208 N = 123 kgf
Example 2 — 10 m² wall at 150 km/h (41.67 m/s):
q = 0.5×1.225×41.67² = 1063 Pa. F = 1.3×10×1063 = 13,820 N = 1409 kgf = 13.8 kN
Example 1 — 2 m² flat plate at 100 km/h (27.78 m/s):
q = 0.5×1.225×27.78² = 472 Pa. F = 1.28×2×472 = 1208 N = 123 kgf
Example 2 — 10 m² wall at 150 km/h (41.67 m/s):
q = 0.5×1.225×41.67² = 1063 Pa. F = 1.3×10×1063 = 13,820 N = 1409 kgf = 13.8 kN
Drag Coefficients for Common Shapes (C_d)
| Shape / Object | C_d | Notes |
|---|---|---|
| Flat plate perpendicular | 1.28 | Maximum drag, face-on to wind |
| Building / solid wall | 1.3–2.0 | Depends on aspect ratio |
| Solar panel (~30° tilt) | 0.4–0.6 | Angle-dependent |
| Antenna dish / parabola | 1.3 | Open or closed dish |
| Cylinder (long) | 0.8–1.2 | Pipe, tower, pole |
| Sphere | 0.47 | Above Re ~1×10⁵ |
| Open lattice frame | 1.3–2.0 | Truss, scaffold |
| Sign / billboard | 1.3 | Flat plate with frame |
| Streamlined body | 0.04–0.1 | Aircraft, bullet shape |
Dynamic Wind Pressure Reference
| Wind Speed | m/s | Dynamic Pressure q | Beaufort Scale |
|---|---|---|---|
| 50 km/h | 13.9 | 118 Pa | 6 (Strong breeze) |
| 100 km/h | 27.8 | 472 Pa | 10 (Storm) |
| 120 km/h | 33.3 | 681 Pa | 11 (Violent storm) |
| 150 km/h | 41.7 | 1063 Pa | 12+ (Hurricane Cat 1) |
| 200 km/h | 55.6 | 1890 Pa | Cat 2/3 hurricane |
| 250 km/h | 69.4 | 2951 Pa | Cat 4/5 hurricane |
💡 Key insight: Wind force is proportional to v². Doubling wind speed quadruples the force. At 100 km/h, a 2 m² flat panel faces about 1.2 kN (123 kg) of force. At 200 km/h, the same panel faces 4.8 kN (489 kg) — four times more. Always design for the maximum credible gust speed at your location, typically 1.5–2× the mean annual wind speed.
Frequently Asked Questions
F = 0.5 × ρ × C_d × A × v². Where ρ = 1.225 kg/m³ (sea level air density), C_d = drag coefficient, A = projected area (m²), v = wind speed (m/s). Dynamic pressure q = 0.5 × 1.225 × v² = 0.6125v² Pa. Then F = C_d × A × q (N).
100 km/h = 27.78 m/s. q = 0.6125 × 27.78² = 0.6125 × 771.7 = 472.7 Pa ≈ 472 N/m². For a flat wall (C_d = 1.3): force per m² = 1.3 × 472 = 614 Pa = 62.6 kgf/m². For a solar panel (C_d = 0.5): 0.5 × 472 = 236 Pa = 24 kgf/m².
Solar panels at 30° tilt: C_d ≈ 0.4–0.6 for the uplift/drag component. ASCE 7 provides specific coefficients for roof-mounted arrays. For preliminary estimation, C_d = 0.5 is commonly used. At a steeper 45° tilt, C_d increases toward 1.0. Always consult the panel mounting manufacturer’s structural data and local building codes for actual design.
Divide km/h by 3.6 to get m/s. Examples: 100 km/h = 27.78 m/s. 120 km/h = 33.33 m/s. 200 km/h = 55.56 m/s. For mph: multiply by 0.44704. For knots: multiply by 0.51444. Always convert to m/s before using the wind load formula F = 0.5ρC_dAv² since the formula requires SI units.
Wind force is proportional to v². Doubling wind speed quadruples force. At 100 km/h: q = 472 Pa. At 200 km/h: q = 1888 Pa (4 times greater). This v² relationship is why hurricane-force winds (200–250 km/h) cause so much more damage than strong gales (100 km/h) — they exert 4–6 times more force on every surface.
For a 1 m² dish (C_d = 1.3) at 120 km/h (33.33 m/s): q = 0.6125 × 33.33² = 681 Pa. F = 1.3 × 1 × 681 = 885 N = 90 kgf. The mast must resist this force plus the moment arm. A 3 m mast creates a bending moment of 885 × 3 = 2655 N·m at the base. Always use design gust speeds (typically 1.5–2× mean wind speed) for structural calculations.
USA: ASCE 7-22 (Minimum Design Loads). Europe: EN 1991-1-4 (Eurocode 1). Australia/NZ: AS/NZS 1170.2. Canada: NBC (National Building Code). Each code defines design wind speeds for each region, exposure categories, importance factors, and load combinations. This calculator provides physics estimates; always use the applicable local standard for structural design.
Wind load is proportional to air density ρ. At 2000 m altitude, ρ ≈ 1.007 kg/m³ (82% of sea level). At 4000 m: ρ ≈ 0.819 kg/m³ (67%). Wind force is reduced proportionally. For a site at 2000 m facing a 100 km/h wind: q = 0.5 × 1.007 × 27.78² = 388 Pa (18% less than sea level). Higher altitude sites have lower air density but can have higher wind speeds.
Mean wind speed is the 10-minute average; gust speed is the 3-second peak. Gusts are typically 1.5–2× the mean speed for a given site and exposure. Since force ∝ v², a gust 1.5× mean produces 2.25× the force of the mean wind. ASCE 7 uses 3-second gust design speeds. UK wind maps use hourly mean. Always verify which definition applies to your design code and site data.
For a 5 m × 2 m sign (10 m², C_d = 1.3) at 150 km/h (41.67 m/s): q = 0.6125 × 41.67² = 1063 Pa. F = 1.3 × 10 × 1063 = 13,820 N = 1409 kgf = 13.8 kN. The supporting structure must also resist the overturning moment: if the sign is 5 m above grade, moment = 13,820 × 5 = 69,100 N·m = 69.1 kN·m at the base. Use a licensed engineer for all sign structures.
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