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Atmospheric Pressure Calculator

ISA Barometric Formula · Elevation Correction

Atmospheric Pressure Calculator
Calculates atmospheric pressure using the ICAO International Standard Atmosphere (ISA) barometric formula. Essential for gauge-to-absolute conversions in flow measurement and equipment sizing per AGA and API standards.
Calculation Mode:

Input

ft
Valid range: -1,000 to 36,089 ft (troposphere)

ISA Barometric Formula

P = P₀ × [1 − (L × h / T₀)]5.2558
P = Pressure (psia)
P₀ = 14.696 psia (sea level)
h = Elevation (ft)
T₀ = 518.67 °R (59°F)
L = 0.00357 °R/ft (lapse rate)
5.2558 = g₀M/(R*L)
Reference: ICAO Doc 7488-CD, US Standard Atmosphere 1976
Valid: Troposphere (−1,000 to 36,089 ft)

Reference Pressures