What is the standard sea-level atmospheric pressure in inches of mercury?

• A. 29.90 inches of mercury
• B. 29.92 inches of mercury
• C. 30.00 inches of mercury
• D. 29.80 inches of mercury

Answer: (B)

Standard sea-level atmospheric pressure is a fixed reference used in aviation and meteorology. It is defined as 29.92 inches of mercury, a value that corresponds to about 1013.25 hPa in the International Standard Atmosphere. This precise figure ensures pilots and weather stations have a consistent baseline for calibrating altimeters and comparing pressure readings globally. Some rough estimates use 30 inches of mercury for ease, but the accepted standard is 29.92 inHg. Values like 29.90 or 29.80 inHg are not the standard reference and are simply minor deviations from the accepted baseline.