Reference · Standards · ASCE/SEI 7-22

ASCE 7 Hazard Tool — Wind, Seismic & Snow Loads

ASCE — the American Society of Civil Engineers — publishes the structural-design load standard ASCE/SEI 7. The associated ASCE Hazard Tool is the official site-hazard lookup for wind speed, seismic ground motion, snow ground load, tornado wind, ice, and tsunami inundation at any US location. This page covers what ASCE is, how to use the Hazard Tool, ASCE 7 risk categories, wind-load calculation procedure, and how the standard has evolved from ASCE 7-88 through ASCE 7-22.

Figure 1 — ASCE 7-22 Hazard Tool: US wind-speed contours and seismic-hazard zones

Use the ASCE Hazard Tool

The official tool is free at asce7hazardtool.online. Enter a US address or coordinates, pick the ASCE 7 edition (7-16 or 7-22) and risk category, and read off site-specific basic wind speed (V), seismic Sd_S and Sd_1, ground snow load, tornado wind, tsunami inundation, and ice thickness. The output PDF includes citation-ready references for use in your structural calculations and stamped drawings.

→ Open ASCE 7 Hazard Tool

The ASCE 7 wind-load formulas

Eq. 01 — Velocity pressure Imperial · ASCE 7-22 § 26.10

q_{z} = 0.00256 \cdot K_{z} \cdot K_{zt} \cdot K_{d} \cdot K_{e} \cdot V^{2}

q_z: velocity pressure at height z, psf
V: basic wind speed (3-s gust at 33 ft), mph
K_z: velocity pressure exposure coefficient (ASCE 7 Table 26.10-1), —
K_zt: topographic factor (hill, ridge, escarpment), —
K_d: wind directionality factor (Table 26.6-1), —
K_e: ground elevation factor, —

Eq. 02 — Design wind pressure (Main Wind Force Resisting System) Imperial · ASCE 7-22 § 27.3

p = q \cdot G \cdot C_{p} - q_{i} \cdot \left( G C_{pi} \right)

p: design wind pressure on element, psf
G: gust effect factor (0.85 typical), —
C_p: external pressure coefficient (Fig. 27.4), —
GC_pi: internal pressure coefficient, —

The Hazard Tool gives you V; ASCE 7 Chapters 26–30 give you the rest. Most jurisdictions require the structural drawings to cite both the ASCE 7 edition (e.g. ASCE 7-22) and the design V, K factors, and resulting design pressures.

Standards: the ASCE 7 family

ASCE 7 has been published roughly every 6 years since 1988. Each edition incorporates updated hazard data and new chapters as needed. The current code in most US jurisdictions:

ASCE 7-22 (2022) — current. Adds Chapter 32 (tornado loads), refined seismic and tsunami procedures.
ASCE 7-16 (2017) — widely used; referenced by IBC 2018 and IBC 2021.
ASCE 7-10 (2010) — major revision: switched from 50-year MRI to multi-MRI risk-category-tied basic wind speeds; introduced ultimate-strength wind design.
ASCE 7-05, 7-02, 7-98, 7-95, 7-93, 7-88 — historical editions; still referenced for pre-existing structures.

ASCE itself (the American Society of Civil Engineers) is the nation\'s oldest engineering society — founded in 1852 by 12 NYC civil engineers, with first president James Laurie. Today: 150 000+ members in 177 countries, with the SEI (Structural Engineering Institute) division responsible for ASCE 7 maintenance.

Reference: ASCE 7 risk categories and wind speeds

Risk Category quick-reference (ASCE 7-22 Table 1.5-1)

Category	Examples	MRI for wind	Importance factor
I	Agricultural buildings, minor storage, low-occupancy	300 years	0.87
II	Most buildings (offices, residential, retail)	700 years	1.00
III	Schools, jails, assembly > 300, day-care > 250	1 700 years	1.15
IV	Hospitals, fire/police/EOC, hazardous-material facilities	3 000 years	1.25

Approximate basic wind speed V (Risk Category II, 3-s gust, 33 ft)

Region	V (mph)	V (m/s)
Miami-Dade County, FL	170–180	76–80
South Florida (Keys)	180–200	80–90
Texas Coast (Houston, Galveston)	130–150	58–67
New York City	115	51
Chicago, IL	105–110	47–49
Denver, CO	105	47
Los Angeles, CA	95	42
Seattle, WA	95	42
Phoenix, AZ	100	45
Honolulu, HI	130	58

How to use the ASCE 7 Hazard Tool, step by step

Open the official ASCE 7 Hazard Tool. Go to asce7hazardtool.online. The tool is free and open without registration. The 2024 version covers ASCE 7-16 and ASCE 7-22 (the active code in most US jurisdictions as of 2024).
Enter the project location. Enter a US street address, ZIP code, or click on the embedded map. The tool uses USGS, NOAA, and FEMA data sources for wind speed, seismic ground motion, snow ground load, tornado wind speed, tsunami inundation depth, and ice thickness — all referenced to the project coordinates.
Select the risk category. Pick the building risk category (I to IV per ASCE 7 Table 1.5-1). Risk Category I — minor structures (low hazard to life). Risk Category II — most buildings (default). Risk Category III — schools, jails, large gathering. Risk Category IV — hospitals, fire stations, emergency-essential facilities.
Read the design wind speed (V). The output gives V_ult (basic wind speed at 33 ft above ground, 3-s gust, MRI corresponding to risk category) in mph. Risk Category II in Miami-Dade ≈ 170 mph; in coastal Texas ≈ 140 mph; in Chicago ≈ 105 mph; in Denver ≈ 105 mph. The tool returns numerical V plus contour maps.
Apply ASCE 7 Chapters 27–30 to compute design wind pressures. Use V_ult with ASCE 7 Chapters 27 (directional procedure), 28 (envelope procedure for low-rise), 29 (other structures), or 30 (components and cladding) to compute design pressures p = q · G · C_p. q = velocity pressure = 0.00256 · K_z · K_zt · K_d · V². The Hazard Tool gives V; you do the rest.
Repeat for seismic, snow, and other loads. The same Hazard Tool gives Sd_S and Sd_1 (seismic), pg (ground snow), Vt (tornado), and ice thickness — each on its own tab with its own ASCE 7 chapter for converting site hazard into design load. Always run all hazard tabs before finalising the structural design.

Worked example: Houston warehouse

A 3-storey warehouse in central Houston, Texas — Risk Category II per ASCE 7-22. Compute basic wind speed and velocity pressure at the top of the structure (roof at 36 ft above grade, Exposure C suburban / open).

Result Site lookup in ASCE Hazard ToolHouston coords + Cat II