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1976 ISA (International Standard Atmosphere) calculator

ISA Press: hPa
ISA Temp: °C

The ISA datum is a theoretical reference level where the weight of the atmosphere is 29.92 "Hg (1013.25 mb/hPa) as measured by a barometer.

This calculator computes the 1976 ISA Pressure and Temperature (above this ISA datum) from the given altitude. The formula used is as follows:

Pb = reference pressure (Pa)
Tb = reference temperature (K)
Lb = temperature lapse rate (K/m) in ISA
h = height at which pressure is calculated (m)
hb = height of reference level b (meters)
R = universal gas constant: 8.3144598 J/(mol┬ĚK)
g0 = gravitational acceleration: 9.80665 m/s2
M = molar mass of Earth's air: 0.0289644 kg/mol

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