Which sea level pressure value is used in the International Standard Atmosphere (ISA)?

In the International Standard Atmosphere (ISA), the value of sea level pressure is set at 1013.2 hPa. This standard was established to create a reference for aviation and meteorological purposes, allowing comparisons and calculations to be made under a uniform baseline of atmospheric conditions. The 1013.2 hPa value is crucial for pilots and meteorologists when assessing altitudes, aircraft performance, and weather patterns, as it represents an average sea level pressure under standard conditions. This standardized pressure helps ensure consistency in communication and data reporting across different regions and altitudes.