Wind Load Calculator (ASCE 7-22)
Calculate design velocity pressure and wind surface pressure for buildings per ASCE 7-22 Chapters 26 through 30. Enter basic wind speed, exposure category, height and enclosure classification to get qz, qh, MWFRS wall pressures, and Components and Cladding zone pressures. Pair this with the snow load calculator to check combined gravity and lateral load cases.
🌬 Wind Load Calculator
ASCE 7-22 Chapters 26-30 | Velocity Pressure, MWFRS & C&C
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View Chart →Velocity Pressure Exposure Coefficient Lookup
Find Kz for your mean roof height and exposure category directly, without running the full calculation. Values below match ASCE 7-22 Table 26.10-1.
| Height z (ft) | Exposure B | Exposure C | Exposure D |
|---|---|---|---|
| 0-15 | 0.57 | 0.85 | 1.03 |
| 20 | 0.62 | 0.90 | 1.08 |
| 25 | 0.66 | 0.94 | 1.12 |
| 30 | 0.70 | 0.98 | 1.16 |
| 40 | 0.76 | 1.04 | 1.22 |
| 50 | 0.81 | 1.09 | 1.27 |
| 60 | 0.85 | 1.13 | 1.31 |
| 70 | 0.89 | 1.17 | 1.34 |
| 80 | 0.93 | 1.21 | 1.38 |
| 100 | 0.99 | 1.26 | 1.43 |
| 120 | 1.04 | 1.31 | 1.48 |
| 160 | 1.13 | 1.39 | 1.55 |
| 200 | 1.20 | 1.46 | 1.61 |
Source: ASCE 7-22, Table 26.10-1 (Velocity Pressure Exposure Coefficients). This calculator interpolates between listed heights.
Calculation Sequence
Basic Wind Speed
Start from the ultimate design wind speed V on ASCE 7-22 Figure 26.5-1 for your Risk Category. This is a strength-level, 3-second gust speed, not a service-level speed.
Exposure and Height
Exposure category and mean roof height set Kz from Table 26.10-1. Rougher upwind terrain (Exposure B) produces lower pressure than open terrain or water (Exposure D) at the same height.
Velocity Pressure
Combine V, Kz, Kzt, Kd and Ke into qz = 0.00256 x Kz x Kzt x Kd x Ke x V^2 per Section 26.10.2, producing a pressure in pounds per square foot.
Surface Pressure
Apply Cp or GCp and GCpi to qz or qh to get the final design pressure on a wall, roof, or cladding element, per Chapter 27 (MWFRS) or Chapter 30 (C&C).
Why Wind Pressure Is Not a Single Number
Unlike a snow load, which acts uniformly downward on a roof, wind pressure varies by location on a building and by which system is being designed. A corner of a roof experiences far higher suction than the middle of the same roof, and the pressure used to size a wall stud is different from the pressure used to size the building's shear walls.
ASCE 7-22 addresses this with two separate procedures. The Main Wind Force Resisting System (MWFRS) procedure in Chapter 27 estimates pressure on the building as a whole, averaged over large areas, for designing frames and lateral systems. The Components and Cladding (C&C) procedure in Chapter 30 estimates localized peak pressure on small elements like a single roof panel or window, which is why C&C pressures are almost always higher than MWFRS pressures at the same location.
The Role of Effective Wind Area in C&C Pressures
C&C pressure coefficients (GCp) decrease as the effective wind area increases, because a larger area is less likely to experience the absolute peak gust across its entire surface at once. A 10 square foot panel near a roof corner can see nearly double the pressure of a 100 square foot area in the same zone. This calculator applies that area-based reduction automatically based on your entered effective wind area.
💡 Tip - Confirm Your Wind Speed Source
Do not use a weather-reported "record wind speed" or a highway sign's advisory speed as your design wind speed. ASCE 7-22's basic wind speed is a statistically derived value tied to a specific mean recurrence interval for your Risk Category, sourced from Figure 26.5-1 or a jurisdiction-adopted wind speed map, not from local weather history.
Worked Example: Suburban Office Building
Project Setup
2-story office, 40 ft x 60 ft plan, 25 ft mean roof height
Chicago-area suburb, Exposure B, enclosed, flat roof
Kd = 0.85, Kzt = 1.0, Ke = 1.0, Kz at 25 ft (Exposure B) ≈ 0.66
These are the baseline inputs every MWFRS calculation needs before any pressure coefficient is applied.
Velocity Pressure at Roof Height
qh = 0.00256 x Kz x Kzt x Kd x Ke x V²
qh = 14.3 psf
This is the reference dynamic pressure used for every wall and roof surface on this building at this exposure and height.
Windward Wall Design Pressure
G = 0.85, Cp = +0.8 (windward), GCpi = ±0.18 (enclosed)
p = 14.3 x 0.85 x 0.8 - 14.3 x (-0.18) = 9.7 + 2.6 = 12.3 psf (inward)
The negative internal pressure case adds to the windward external pressure, which is why both signs of GCpi must be checked for each surface.
Frequent Wind Load Calculation Mistakes
⚠ Errors That Change the Result
- Using the wrong Risk Category map: ASCE 7-22 publishes separate wind speed maps for Risk Category I, II, III and IV. Reading a value off the wrong figure directly changes V, and since pressure scales with V squared, a small map error produces a large pressure error.
- Confusing service-level and strength-level wind speed: Since ASCE 7-10, published basic wind speeds are already at strength level. Do not apply an additional 0.6 factor when using LRFD load combinations; that factor is only for converting to ASD service-level loads.
- Applying MWFRS pressures to design cladding: C&C elements need the Chapter 30 procedure with zone-based GCp values, which are typically higher than MWFRS Cp values for the same location on the building.
- Ignoring GCpi sign convention: Both the positive and negative internal pressure cases must be evaluated separately for each surface; the governing case is not the same for windward and leeward walls.
- Skipping topographic effects on hills: Sites on isolated hills, ridges or escarpments require a calculated Kzt greater than 1.0 per Section 26.8. Assuming flat-terrain Kzt = 1.0 on a hilltop site understates pressure significantly.
Using Wind Pressure Results for Permits and Framing
Building departments in wind-prone regions typically require the basic wind speed, exposure category, and resulting design pressures to be shown on permit drawings for new construction, additions, roof replacements, and window or door replacements in coastal counties. Many jurisdictions along the Gulf Coast and Atlantic seaboard also require product approval numbers showing that installed windows, doors, and roof coverings are rated for the calculated C&C pressure at their location on the building.
This calculator estimates the pressures an engineer would use as a starting point. For anything beyond a preliminary check, primary structural framing, or a permit submission, the load path, connections, and final pressures must be verified and stamped by a licensed structural engineer per IBC 2024 Section 1604. Use the beam load calculator to carry these wind pressures into member sizing once the surface pressure is confirmed.
Frequently Asked Questions
ASCE 7-22 Section 26.10.2 gives velocity pressure as qz = 0.00256 x Kz x Kzt x Kd x Ke x V^2, in pounds per square foot, where V is the basic wind speed in mph. Design wind pressure for a wall or roof surface is then p = q x G x Cp minus qi x GCpi per Chapter 27 for the Directional Procedure.
Per ASCE 7-22 Section 26.7, Exposure B applies to urban and suburban areas with closely spaced obstructions for at least 1,500 feet upwind. Exposure C is open terrain with scattered obstructions under 30 feet and is the default when a site does not clearly qualify for B or D. Exposure D applies within 1,500 feet of large bodies of water such as oceans or the Great Lakes.
MWFRS (Main Wind Force Resisting System) pressures per ASCE 7-22 Chapter 27 apply to the overall structural frame, shear walls and diaphragms. Components and Cladding (C&C) pressures per Chapter 30 apply to individual elements like roof panels, siding and windows with small tributary areas, and are generally higher at corners and edges because local peak suction is not averaged over a large area.
Per ASCE 7-22 Table 26.13-1, enclosed buildings use GCpi = plus or minus 0.18. Partially enclosed buildings use GCpi = plus or minus 0.55. Open buildings, where at least 80 percent of each wall is open, use GCpi = 0.00. Both the positive and negative case must be checked because the sign that governs depends on the surface being designed.
Wind speed increases with height above ground because ground friction slows air movement near the surface. The velocity pressure exposure coefficient Kz in ASCE 7-22 Table 26.10-1 increases with height for this reason. For Exposure C, Kz rises from about 0.85 near ground level to roughly 1.26 at 100 feet, meaning velocity pressure at 100 feet is about 48 percent higher than at ground level for the same wind speed.
Kzt per ASCE 7-22 Section 26.8 accounts for wind speed-up over isolated hills, ridges and escarpments. Kzt = 1.0 for flat or gently rolling terrain. On qualifying hilltops or ridge crests, Kzt is calculated from Kzt = (1 + K1 x K2 x K3)^2 using the site's height-to-length ratio and position relative to the crest, and can reach 1.5 to 2.0 in severe cases.
No. This calculator estimates ASCE 7-22 velocity pressure and basic MWFRS or C&C surface pressures for planning purposes. Permitted structural work, including load path design, connections, and code compliance review, must be completed and stamped by a licensed structural engineer per IBC 2024 Section 1604.
Sources and Methodology
- ASCE/SEI 7-22, "Minimum Design Loads and Associated Criteria for Buildings and Other Structures," Chapter 26 (Wind Loads: General Requirements), American Society of Civil Engineers.
- ASCE/SEI 7-22, Chapter 27 (Wind Loads on Buildings: MWFRS, Directional Procedure).
- ASCE/SEI 7-22, Chapter 30 (Wind Loads: Components and Cladding).
- ASCE/SEI 7-22, Table 26.10-1 (Velocity Pressure Exposure Coefficients).
- ASCE/SEI 7-22, Table 26.13-1 (Internal Pressure Coefficients).
- ASCE/SEI 7-22, Table 26.6-1 (Wind Directionality Factor Kd).
- IBC 2024, Section 1604 (General Design Requirements, licensed design professional review).
Last reviewed: September 2026. Reviewed by site author.
Disclaimer
This calculator provides estimates for planning purposes. For permitted structural work, foundations, multi-story construction, retaining walls over 4 feet, and commercial projects, calculations must be verified by a licensed structural engineer per IBC 2024 Section 1604. ConcreteCalculate.com is not liable for structural decisions made from these estimates.
Built by Muhammad Ramzan Babar, physics researcher (PhD candidate). Reviewed by site author.
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