ASCE 7-22 · ULTIMATE & NOMINAL PRESSURES

Ultimate & Nominal Wind Pressure Calculator

Strength-level (ultimate) and service-level (nominal) design pressures from one ASCE 7 calculation. Enter a ZIP and the calculator handles the load combinations.

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UltimateSTRENGTH · LRFD · 1.0W

NominalSERVICE · ASD · 0.6W

Since 2002MULTIPLE ASCE 7 EDITIONS

THE 0.6 RELATIONSHIP

One calculation, two pressures

Since ASCE 7-10 the mapped basic wind speed is ultimate (strength-level). The nominal pressure is exactly 0.6× the ultimate pressure — and because pressure scales with the square of speed, the equivalent speed ratio is √0.6 ≈ 0.775.

AT A GLANCE

Ultimate vs nominal, side by side

Ultimate (Strength)

The pressure built from the mapped ASCE 7 wind speed since 7-10. Used directly in LRFD with a 1.0W factor at the strength limit state.

LRFD · 1.0W

Nominal (Service)

The service-level value used in ASD and for deflection checks. Equal to the ultimate pressure × 0.6 — nominal speed ≈ 0.775 V.

ASD · 0.6W

WHICH PRESSURE GOES WHERE

Reference comparison

Aspect	Ultimate	Nominal
Design method	LRFD (strength design)	ASD (allowable stress)
Load factor on W	1.0W	0.6W
Limit state	Strength / failure level	Service level
Map basis (ASCE 7-10+)	Mapped V is ultimate	Derived: pressure × 0.6
Pressure relation	1.00×	0.60× ultimate
Speed relation	V (mapped)	≈ 0.775 V
Typical use	Member strength checks	Drift, DP ratings, ASD combos

WORKED EXAMPLE

From ultimate to nominal

Start with a mapped ultimate speed and walk it down to the service-level equivalents.

Mapped ultimate speed

V_ult = 150 mph
Read directly from the ASCE 7-22 basic wind-speed map.

STEP 1

Nominal speed

V_nom = V_ult × √0.6
= 150 × 0.775 ≈ 116 mph

STEP 2

Nominal pressure

p_nom = 0.6 × p_ult
Service pressure = 60% of strength pressure.

STEP 3

Key: 150 mph ultimate → about 116 mph nominal. Same wind, two reference levels — never apply the 0.6 factor twice.

WHY USE THE CALCULATOR

Both pressures, done right

Factors applied for you

1.0W for LRFD, 0.6W for ASD — the right load factor every time, no manual conversions.

AUTOMATIC

ZIP-driven lookup

One ZIP pre-fills the ASCE 7-22 basic wind speed so you start from the right strength-level input.

ASCE 7-22

ASD and LRFD together

Strength and service pressures from a single run — ready for member checks and serviceability alike.

ASD + LRFD

Proven since 2002

Built by structural engineers and trusted across multiple ASCE 7 editions by architects, contractors, and PEs.

TRUSTED

WHY THE MAPS CHANGED

The ASCE 7-10 map shift

Through ASCE 7-05, the printed wind-speed maps were nominal (service-level), and LRFD applied a 1.6W factor to reach strength.

Starting with ASCE 7-10, the maps were re-cast as ultimate (strength-level) speeds. LRFD now uses 1.0W directly, and ASD recovers the service level with 0.6W.

Compare an old 90 mph map to a new 115 mph map and the design intent is unchanged — only the reference level moved from nominal to ultimate.

CALCULATE BOTH AUTOMATICALLY

Get nominal and ultimate in one run

WindLoadCalc.com returns ultimate (LRFD) and nominal (ASD) pressures from a single ASCE 7-22 calculation — no manual 0.6 conversions.

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